Plenums and the wasting "option"

[barryhc]

Originally posted by fppf
I'm all about details, thats where the devel is.

It says something to work with Ti, but you already know that.
Does your proccess require you to weld or just machine. Not that machining it is easy, but welding adds that extra little plus! Every try to drill "Super Invar"

No, never heard of "Invar", but I've done Hastelloy grades "B", "C", and "D" along with Pure Nickel( yeah I said 100% pure ) Inconel, Tantalum ( now that is a Bi---! ), and a good number of particularly "Exotic" materials, along with 7 grades of "plastics", and some "G10" glass material for Fermilab.

Got into some "Electron Beam Welding" years ago, having to do with the "Joint US-Soviet Space Mission' in the 70's.

Life is Is a "Box of Chocolates"! > barryhc

[fppf]

Oh yeah, we did some Hastelloy
Our oil industry pressure xducers where Inconel X750.
Anyway we are getting off topic here.

[barryhc]

Well, a little engineering "banter" there, heh? It's not so difficult, really, and "fppf" is quite right about testing.

It's quite easy to do "before installation" and can be done before gluing as well, so it is well worth it to have no "nagging doubts", once you start pouring in the "sand" ( or whatever ). It wouldn't be all that hard to make a new set of feeder tubes with holes, if you were disappointed with the test results.

I put mine on the pool deck, and fired up a 175gph power head. My feeder holes happen to be drilled both in the top and the bottom of the feeder tubes, and when the water squirted up, it was between 6" high near the center, and 5.5" high at the ends.

This was of course, on the little hex. version. and it should be carried out on any system before installation. Probably about a 350 gph Powerhead for the 55 gal. version. No "Black Art" after this test.

I think that the "delta loss" values calculated previously, are not quite accurate, because of the central manifold tube design, and not having taken into account the 33-50% restriction factor.

I will "delve up" some real accurate flow loss calculations for this shortly to include friction loss over tube length, etc., unless of course "fppf" would like to handle this for us ( hint, hint ).

And the point made by "fppf", about the ratio of "volume of water in the substrate" to the "volume of substrate, that water is in", is truly a revelation. I really needed that.

This might put my 7/64" draw depth value up to 7/8" in the substrate, while it becomes about 5/32" in the plenum area, due to the space the plenum itself takes up, in my particular design.

I don't think this calculation of water space taken up by the plenum itself, is of much concern really, but the draw depth is particularly important to me regarding the bacterias' response to Oxygen input.

So, now it would only take 8 days for this oxygenated water to reach the plenum ( in 7" depth of substrate ), at 7/8" per day, and 1 "one pint draw" per day.

That's still about 4 gal. per month, which is about 20% of the 20 gal. of actual water, in my particular 27 gal. hex tank. Not that bad, as a water change volume. Randy Holmes Farley has shown, that daily water change intervals are no less than 74% as efficient as monthly water changes, of the same total monthly amount. That's good enough for me, at least I'm not using too much water here, and I can change any more out that I like with other methods.

I'll keep looking for information on the bacteria, and how they might respond to periodic oxygenation. I really want to keep an Anaerobic ( no oxygen ) area in the bottom 1" or so of the substrate itself, above the plenum, for Phosphate and "nasties" processing.

So, off we go again, let's see where it leads us. Thanks all, > barryhc

[fppf]

That sounds like a valid test, one would think the numbers would work out the same or close when the draw is do, aka flip the sign.

Have you gave any thought to how much delta pressure will be needed to get the wanted flow through the sand bed?

Maybe the answer to the oxygen problem is to get rid of the oxygen? Maybe a second manifold about an inch or so below the surface of the bed could inject water that is anoxic, the you could flush as much as you want.

[barryhc]

Originally posted by fppf
That sounds like a valid test, one would think the numbers would work out the same or close when the draw is do, aka flip the sign.

Have you gave any thought to how much delta pressure will be needed to get the wanted flow through the sand bed?

Well no, actually, because "we" haven't been able to establish what the depth and particle sizes are going to be. For my setup, I'm "leaning" towards about 7" of Arag., layered as such:

> 3/4" of 3-5mm directly above the plenum screen
> 3/4" of 2-4mm above that
> 3/4" of .7-1.7mm above that
>> then the "critter screen", probably about 6mm openings here to stop "critters" only.
> 2" of "oolitic" ( sugar ) sand
> 2 3/4" of 1-4mm

Were up to the surface here, and there wont be any "sandstorms" in my tank, even with flow at 30-40 times the actual water volume.

Originally posted by fppf
Maybe the answer to the oxygen problem is to get rid of the oxygen? Maybe a second manifold about an inch or so below the surface of the bed could inject water that is anoxic, the you could flush as much as you want.

H-M-M-M- . . . I think that the bacterial populations need to process the nutrients "down" ( diffusion ) to get the best nutrient processing done in what I now call the "low oxygen zone". this is what I'm working on the most lately, is the bacterial processes. Below this "low oxygen" area, we have the "no oxygen" zone which I hope to be an inch or more thick, and where sulfide, and other "nasties" are normally processed. This is the area where most "DSB crashes" supposedly come from, and is what we want to "waste".

I made a thread, for the investigation of proper nomenclature, and these nutrient and compound processing bacteria, called "Bacteria-Anaerobic-Anoxic"? in advanced topics.

There some excellent links there. Another one, is "Biological Phosphorous Removal", which has some good information, including anoxic and anaerobic bacterial processing and "forced oxygen level" fluctuations that "they" are using in Municipal Water Systems. This includes "Phosphate processing", and is exceedingly intresting.

I'm not throwing out the second manifold idea, but I have to think about it a "good bit". I'm pretty patient about these things, and I like to let "the soup" simmer awhile before it's ready for "serving".

Thanks, > barryhc

[barryhc]

You know, as I review the previous post with the "layering model" that I'm considering for my particular set-up, it occurs to me, that the lower layer, or layers of the bed, need not be aragonite.

In fact, why has everyone been "running toward" aragonite anyway? Now it's got some porosity to harbor bacteria I believe, but wasn't the big "feature" supposed to be calcium and alkalinity buffering? Isn't this buffering supposed to occur because of low pH, and isn't it because of the substrate "melting" in the low pH, and isn't that what causes some form of "P leaching", that is complained about a lot?

Now if we're wasting frequently, then why would we care about the P, if it is going "down the toilet" anyway? But why have our "gravel membrane" melting, and eventually clogging and falling through the lower screen, when we could use a less soluble "substrate down there near the plenum. The bacterial activity "down there is going down the drain as well, so?

If calcium and alkalinity can be managed reasonably in a bare bottom system, then certianly, it can be managed in a "substrate" system just as easily.

I want the "sand and gravel" because the critters want it! And I like to look at it. ( and the critters )

If we can process some nitrate in there in the upper layers, then good, of course, and if we can dump some waste from that process "out the bottom" while we're at it, then "so much the better"!

So, in my case here, if the wasting plenum "avoids the crash", my objective is accomplished. If the system processes nutrients better, then that is very worthwhile also.

What is your objective here? "Chime in for sure"! > barryhc

[inwall75]

Ouch.

I read the WHHHHOOOOOLLLLEEE thread.

I just communicated with LDRHawke via a different bulletin board the other day and it is true that he isn't using this method anymore. (I don't know him at all). However, he stated that he did get it to work well. His reason for stopping using it wasn't because it failed. He just wasn't interested in critters that require sand so it didn't make sense for him to continue with it.

BTW....he hasn't stopped experimenting. Check out his bubble filtration in the main tank. http://homepage.mac.com/johnlaurenso...ersonal41.html

In fact, why has everyone been "running toward" aragonite anyway? Now it's got some porosity to harbor bacteria I believe, but wasn't the big "feature" supposed to be calcium and alkalinity buffering? Isn't this buffering supposed to occur because of low pH, and isn't it because of the substrate "melting" in the low pH, and isn't that what causes some form of "P leaching", that is complained about a lot?

The "big feature" is HIGHLY overrated. I've run both BB and DSB systems and while I've never measured it, I can tell you via observation that you truly aren't getting the buffering that is widely accepted as fact. Are you getting a little...sure. But I'll tell you what, sand is the MOST EXPENSIVE buffer there is. Does the P leach into the water column from the bottom levels. Not likely as bacteria will grab onto quickly or it will readsorb to the CaCO3 in the higher levels where the pH is higher.

P can leach into the water column with a typical sandbed after a period of time. However, this particular system, if done properly will take care of the problems that lead to this.

[barryhc]

Thanks Curt, So it appears that we have at least one vote for phosphate processing, and we can widen our horizons on what can be used for substrate.

I think that for occcasional wasting, substrate material may be a bit more important, but for frequent wasting, you can probably use just about anything, below the top 1 1/2". Particle size, is a different story, however, and the discussion remains open of course on it's effects relative to bacteria etc.

Any thoughts Curt, or anyone, on specific oxygen saturation levels and the related bacterial activity, as well as bacterial recovery time?

Thanks again Curt, need any "Murine or Tylenol" after that long read. > barryhc

[barryhc]

Ok folks, so I'm "bumping the thread". I have stated before, that this is a "long term" project, and I do not expect it fail.

Some people "do or will" consider this, too complex to "fiddle with". I submit that a captive reef system is complex, and that will not "go away".

I do expect that when enough is known about the bacterialogical processes, and how they are affected by "forced downflow", that a considerable level of improvement will have been identified, for those reef keepers who wish for whatever reason, to operate a reef system that utilizes "substrate" for the well being of animals that prefer or require it, and/or for the enthusiast who simply prefers "the look" that is coincidentally available.

Others, may have ideas about the implementation, and insights or concerns, regarding the health of the bacterial populations within the "substrate".

I will state again that this only a supplement, or sub-function of the "system" as a whole and that good husbandry, water flow, skimming, species seletion, parameter testing, and on et. al., is necessary to maintain any reef system for the long term.

Thanks to all, and happy reef keeping > barryhc

["Umm, fish?"]

Hey! I was just thinking that it was about time to bump the thread again. Have you starting sucking water yet? If so, did you test the waste? Any numbers?

I just about have my grid built. Silly hardware store ran out of 1/2" crosses, so I have to wait for a bit.

Cheers!

Andy

[barryhc]

Originally posted by "Umm, fish?"
Hey! I was just thinking that it was about time to bump the thread again. Have you starting sucking water yet? If so, did you test the waste? Any numbers?

Cheers!

Andy

No, I have been trying to get done with my "spring yard work" before next spring arrives, and I'm designing a refugium, and it has a DIY skimmer in it ( that requires a good bit of investigation as well ), and . . . .

Oh well, I will start drawing water from the plenum pretty soon. I will start with a "manual draw" of 1 pint, once a day. That is supposed to be 7/64" of water column "down flow" each day. If you have been following the thread closely, you should understand that this represents approx. 7/8" of "downflow distance" in "the substrate" itself. Please ask about this if you do not understand what is being said here, it is absolutely crucial to the understanding of bacterial populations, and their recovery rate.

Thanks for posting, this going to work, I am quite sure. > barryhc

[inwall75]

Originally posted by barryhc
Thanks Curt, So it appears that we have at least one vote for phosphate processing, and we can widen our horizons on what can be used for substrate.

I think that for occcasional wasting, substrate material may be a bit more important, but for frequent wasting, you can probably use just about anything, below the top 1 1/2". Particle size, is a different story, however, and the discussion remains open of course on it's effects relative to bacteria etc.

Any thoughts Curt, or anyone, on specific oxygen saturation levels and the related bacterial activity, as well as bacterial recovery time?

Thanks again Curt, need any "Murine or Tylenol" after that long read. > barryhc

Or at least Phosphate recycling.

Since the last time I read this thread, I've been running around with my head chopped off. Someone please remind me. Has there been any discussion of an inline pH monitor to determine the pH of the water being drawn off? That could be very useful IMO at determining if you've drawn off too much water or if a smaller amount of water was drawn off too quickly.

Bacterial recovery time is so difficult for me to wrap my head around. Here's why. Provided the proper Oxygen environment, the only thing that needs to occur to have a very quick recovery time is sufficient nutrients. The bacterial population grows on a logarithmic basis every 30 minutes or so IIRC. 1 bacterium would be 2 and in 30 minutes you would have 4 and so on. Look at these numbers and you can see just how quickly they can grow.

1,2,4,8,16,32,64,128,256,512, etc. Since we are going to be starting out with much higher populations to begin with our only limiting factor is going to be how quickly the combination of diffusion and bacterial migration will get Nitrogenous compounds into the sandbed.

[barryhc]

Originally posted by inwall75
Or at least Phosphate recycling.

Since the last time I read this thread, I've been running around with my head chopped off. Someone please remind me. Has there been any discussion of an inline pH monitor to determine the pH of the water being drawn off? That could be very useful IMO at determining if you've drawn off too much water or if a smaller amount of water was drawn off too quickly.

Bacterial recovery time is so difficult for me to wrap my head around. Here's why. Provided the proper Oxygen environment, the only thing that needs to occur to have a very quick recovery time is sufficient nutrients. The bacterial population grows on a logarithmic basis every 30 minutes or so IIRC. 1 bacterium would be 2 and in 30 minutes you would have 4 and so on. Look at these numbers and you can see just how quickly they can grow.

1,2,4,8,16,32,64,128,256,512, etc. Since we are going to be starting out with much higher populations to begin with our only limiting factor is going to be how quickly the combination of diffusion and bacterial migration will get Nitrogenous compounds into the sandbed.

All right, now "I" am trying to get my mind around "this". "Sort-of".

You see, I have always felt "instinctually" that this wasn't going to be that much of a problem, for the very reasons that you state, but, there has been so much "riff-raff" about how the "entire bacterial population" is going to "be destroyed", that I have found it difficult to proceed.

There is going to be a "gradation" in the oxygen level of the substrate, and that gradation is going to be "modified" by "Wasting", as I have stated "forever", but the downflow can br tuned to cause this gradation to occur in the way that "we" desire, If we can determine what it is that we desire.

So, whether it is pH, or oxygen, or better yet both, the evaluation of "effluent" is going to be "key" to developing "the system".

I don't think there is any way for us to know ahead of time, and the reason I've been working so hard thus far, "ahead of time", is
in order to develop the "substrate model", and you can see that I have gone to a "layering scheme", which drives a lot of people "bonkers".

I have the little hex tank, which is my little experiment, but I'm getting ready for a 200 to 300 gal. tank in December, and I will have decided about the "substrate model" by then.

So, Curt, I think you are right on here, with the "testing", and I hope to start "drawing and testing" within a week.

Please stay with us here, your input is highly valuable.

> barryhc

[inwall75]

Originally posted by barryhc
You see, I have always felt "instinctually" that this wasn't going to be that much of a problem, for the very reasons that you state, but, there has been so much "riff-raff" about how the "entire bacterial population" is going to "be destroyed", that I have found it difficult to proceed.

I completely agree with you. Here's an interesting experiment. Take a small piece of a frozen prawn, put it in an airtight rubbermaid container and immediately put it in the fridge to thaw out. Wash your hands ahead of time but not with an antibacterial soap. Then mix up some saltwater (i.e. not tank water) and add it to the rubbermaid container. Then take a small amount of sand out of the sandbed in an established tank. You don't have to add a 6 inch sandbed. Lay the sand out on some paper towels so that the sand is dry. I can guarantee you will see that small piece of shrimp rot even though supposedly, we've nearly wiped out all of the bacteria. Over a period of time, you could do Ammonia, Nitrite, and Nitrate tests on the container and you will see a cycle...all started from airborne bacteria.

You could do this exact same thing without adding sand. Airborne bacteria would be in there fairly quickly. Bacteria are highly adaptive. They don't merely migrate to the proper areas, they will create their own environment. There is Nitrification AND denitrification occuring in a biofilm so thin on your front glass that you can see through it. They can create any Oxygen condition they need to. Can these biofilms handle the typical bioload of a reef tank? NOT EVEN CLOSE. That's why the Berlin method of adding LR completely changed this hobby. More surface area=more bacteria=more nitrification.

Originally posted by barryhc

There is going to be a "gradation" in the oxygen level of the substrate, and that gradation is going to be "modified" by "Wasting", as I have stated "forever", but the downflow can br tuned to cause this gradation to occur in the way that "we" desire, If we can determine what it is that we desire.

So, whether it is pH, or oxygen, or better yet both, the evaluation of "effluent" is going to be "key" to developing "the system".

I don't think there is any way for us to know ahead of time, and the reason I've been working so hard thus far, "ahead of time", is
in order to develop the "substrate model", and you can see that I have gone to a "layering scheme", which drives a lot of people "bonkers".

My thought on the pH moniter is basically that you can deduce Oxygen levels via pH. IMO, you can decide when the draw it too much, too quick, etc. THAT IS if you are terrified of killing all of the bacteria. If you tried to do a 6" sandbed made of oolithic grains on top of this plenum, I truly believe that it would take some time for effective denitrification (that can support a typical reeftank) to be re-established. However, what you are doing is setting up a system of removing waste, nutrients, and solids, but since you are using a more open pore-space between grains, they should re-establish quickly. What we have to remember....what we DON'T want in our water column, is life-giving food for bacteria.

BTW, the reason I think that people go "bonkers" is because there is no hard and fast rule. People beg to know watts per gallon for lighting, gallons per hour of flow, etc. This is an unknown that you are delving into and you are correct, experimentation is the only way.

[barryhc]

Originally posted by inwall75
I completely agree with you. Bacteria are highly adaptive. They don't merely migrate to the proper areas, they will create their own environment. More surface area=more bacteria=more nitrification.

Curt, are you familiar with the "supposedly" very thin "low oxygen zone" that supports "Faculative-non-obligate-anaerobes" that are supposed to be responsible for much of the "Nitrite to Nitrate" processing in a "sand bed"?

I have found this originally in the "Goemans and Gamble" literature, but also in very many other "professional studies and dissertations". Waste treatment is "rampant" with such discussions, as well as some advanced "disections" of "Vodka Dosing" and similar "forced bacterial activity" endeavors.

My thought on the pH moniter is basically that you can deduce Oxygen levels via pH. IMO, you can decide when the draw it too much, too quick, etc. THAT IS if you are terrified of killing all of the bacteria.

Well, I'm not, but it would be good for verification that the "bacrerial population" is being "controlled". And a "report" from a controller to a "log" would be extremely helpful. I'm working on this currently, as a side investigation on "controllers".

If you tried to do a 6" sandbed made of oolithic grains on top of this plenum, I truly believe that it would take some time for effective denitrification (that can support a typical reeftank) to be re-established.

I,m losing it here, please explain. We should not have to re-establish a bacterial population, if we did not decimate it in the first place, which is the primary function of "High Frequency" VS "occasional" plenum "Wasting".

However, what you are doing is setting up a system of removing waste, nutrients, and solids, but since you are using a more open pore-space between grains, they should re-establish quickly.

You should look at my "layering-scheme" earlier on this page, or on the last page. While many systems might come from this investigation, the "High Frequency" version is being "touted" almost exclusively by me. I insist that "solids" should be removed nearly identicaly to a BB system, by way of the "substrate layering scheme", high-flow, "live-rock elevation", and with "critters", that keep "poop", algae, and detritus in suspension, for skimming and or mechanical filtration. ( skimming highly preferred here )

Bacteria populations should not need to "re-establish", for any depth or distance greater than that which causes them "no difficulty whatsoever".

High frequency wasting, should create an oxygen gradation that is effectively "permanent and continuous". Any "recovery" should only need to occur over a very short distance, like 1/8" to possibly as high as 1" in the substrate, and "never" any "oxygen flushing" of the substrate, that would require any re-establishing of the bacteria population to occur over any period of time longer than "SAY" 1 or 2 hours, and for not more than a "distance or depth" of more than about 1/2".

What we have to remember....what we DON'T want in our water column, is life-giving food for bacteria.

H-m-m-m-m . . . Well, I think I might be following you here, you mean Nitrates and phosphates, for algae growth, and "let's skim everything we can", or am I missing the meaning here?

BTW, the reason I think that people go "bonkers" is because there is no hard and fast rule. People beg to know watts per gallon for lighting, gallons per hour of flow, etc. This is an unknown that you are delving into and you are correct, experimentation is the only way.

Well, no "magic bullet" for sure, and you are again, right on, that experimentation, testing of effluent, and tank parameters, is paramount.

I've been a bit "picky" with you here Curt, but it is for accuracy, and not for offense or defense of "anything".

Please stay with us, I particularly appreciate your input. More of what you have stated here has been taken "to heart", than might be immediately obvious!

Thanks again, barryhc

["Umm, fish?"]

If you tried to do a 6" sandbed made of oolithic grains on top of this plenum, I truly believe that it would take some time for effective denitrification (that can support a typical reeftank) to be re-established.

I think this would be true only if one effectively drained the entire sandbed. I think that no matter what we do there will be channeling in the bed that will leave areas of the bed relatively unscathed. I think the bacterial population in the bed will be able to recover from the untouched areas pretty quickly.

[barryhc]

Originally posted by "Umm, fish?"
I think this would be true only if one effectively drained the entire sandbed.

I agree entirely.

I think that no matter what we do there will be channeling in the bed that will leave areas of the bed relatively unscathed. I think the bacterial population in the bed will be able to recover from the untouched areas pretty quickly. [/B]

I have gone to a lot of trouble to avoid channeling, and I think to good effect, however, I agree that some channeling might still occur, and while I do not think that it will unduly "compromise" the remainder of the bed, I agree, that the affected areas should be able to recover rather quickly.

The "lower layers" below the "critter screen" are intended to remain "stable", and allow for these fluctuations in the "upper layers".

Good points "Fish".

> barryhc

["Umm, fish?"]

To really explain why I think channeling is okay, I think I need to explain my theory of why DSBs "leak" (I hate that term) phosphate. So please bear with me and please tell me if I'm way off-base (or even a little off-base ). This is all simplified, but it's how I organize the problem in my head:

All populations of critters are limited by many factors. Now DSBs give bacteria huge chunks of real estate to call home, but it is still a finite resource and they reproduce like mad, so living space can eventually be a limiting factor of the bacteria population.

The bacteria in our sand bed not only participate in the nitrogen cycle, they also bind phosphate. Not much (they're small), but there are enormous numbers of them.

When a bacterium dies, the stuff it's binding in it's "body" gets released.

A lot of the phosphate we put into our systems never makes it back out again.

If you take all of these factors into consideration, you can see that the bacteria in the sand bed will take in and hold the phosphate we add, PLUS all the phosphate that's been released from every bacterial generation, right up to the point where the bacterial population runs out of room to expand. At that point, there will no longer be phosphorous uptake (by the bacterial population).

So the question you have is: how does this apply to anything?

I want to drain my DSB infrequently to a) get any crap out of the bed I can and b) to kill off a subset of the bacteria to open up real estate for expansion. If I drain infrequently it gives the sand bed time to settle back down and the bacteria time to re-colonize.

That's my reasoning. Please shoot holes in it.

Andy

[barryhc]

Originally posted by "Umm, fish?"
All populations of critters are limited by many factors. Now DSBs give bacteria huge chunks of real estate to call home, but it is still a finite resource and they reproduce like mad, so living space can eventually be a limiting factor of the bacteria population.

How long is eventually?

The bacteria in our sand bed not only participate in the nitrogen cycle, they also bind phosphate. Not much (they're small), but there are enormous numbers of them.

When a bacterium dies, the stuff it's binding in it's "body" gets released.

A lot of the phosphate we put into our systems never makes it back out again.

Yes, I'm following here.

If you take all of these factors into consideration, you can see that the bacteria in the sand bed will take in and hold the phosphate we add, PLUS all the phosphate that's been released from every bacterial generation, right up to the point where the bacterial population runs out of room to expand. At that point, there will no longer be phosphorous uptake (by the bacterial population).

H-m-m-m . . .

I want to drain my DSB infrequently to a) get any crap out of the bed I can and b) to kill off a subset of the bacteria to open up real estate for expansion. If I drain infrequently it gives the sand bed time to settle back down and the bacteria time to re-colonize.

Well, I follow just about everything that you are saying here. I have a few points to make, regarding the benefits that I expect to receive from wasting frequently.

>Firstly, I am lazy, and I hate water changes. I am absolutely dead serious here. Frequent Wasting will cause a "continuous water change" to occur automaticaly, and forever. For me that is a very nice feature. "Continuous water changes" are 74% as effecient as monthly water changes of the same monthly volume, and that is good enough for me. At the 1 pint per day for my system, that is equivalent to a 17% water change monthly. I highly prefer this continuous condition to "all at once" water changing.

I would have to go to considerably more trouble to put together an automated water change system here, so "complexity wise" this is just easier and less expensive anyway.

>>Secondly, frequent wasting will "stretch" the bacterial populations, causing the aerobic zone to be a "bit deeper". This top Aerobic zone is only about 1/2 to 1" thick to begin with, and may become up to 1/2" thicker, but not more, so what is the problem with that?

The "low oxygen" zone comes below this where most processing of Nitrite to Nitrate occurs, and it is generally regarded to be only about .5 to 1mm thick. This is where "non-obligate-Anaerobic-faculative- bacteria" do Nitrate "processing. This is generally accepted fact by many "authorities" on the subject, and if it does not "sit well" with anyone, then this is where the bacterialogical discussion needs to continue!

The "stretching" of the bacteria populations, could increase the depth of this "low oxygen" zone to between 3-6mm thick, which would represent a 4 to 8 times factor of improved Nitrate processing power. I like that too!

So now, "we" have used up about 1 1/2" to 2" of the top level of the substrate so far, and in my 7" deep "substrate model", that still leaves us with at least 5" of remaining substrate for the Anaerobic zone. Gee, I don't see that as being inadequate, and it allows probably at least another 3 to 4" of substrate to account for my conceptual errors, or whatever else a person ( or critter )might want it for.

This "oxygen gradation" will be controlled by frequency and "draw depth" as necessary, and THERE WILL NOT BE OXYGENATED WATER anywhere near the plenum!!!!!!!!!!!!!!!!!!!!!!!! period.

>>>Thirdly, this process will be "effectively continuous", which eliminates concerns about "what happened when I wasted the plenun". There is no "when I wasted the plenum", because I am "always wasting the plenum".

So while some ( or a lot of ) "diffusion" will continue to occur, relative to the "water column", in the top 2" or so, the nastier processes "below" have plenty of room, and most of it is "on it's way down" anyway!

It is not undergoing some questionable "big change".

That's my reasoning. Are there any holes in it?

Thanks, > barryhc

[reefclown]

The "low oxygen" zone comes below this where most processing of Nitrite to Nitrate occurs, and it is generally regarded to be only about .5 to 1mm thick. This is where "non-obligate-Anaerobic-faculative- bacteria" do Nitrate "processing. This is generally accepted fact by many "authorities" on the subject, and if it does not "sit well" with anyone, then this is where the bacterialogical discussion needs to continue!

Barry, how far have you considered the possibility of biofilms that coat every available surface area in the tank, i,e the entire cycle occurs within a microns layer on every availabe surface regardless of the presence of 'sediment zones'

here's a random sulphur based extract that demonstrates the concept, there are millions of accredited marine biofilm articles out there.

http://aem.asm.org/cgi/content/full/65/11/5107

i.e. do you accept that biofilms coat every surface and in themselves are capable of completing the full nitrogen/sulfur//phosphate/e.t.c cycle at the micron level?

Isn't all that remains a method of gettind the most detritus out of system before it has chance to cycle in the biofilms?

I'm a technologist by trade who neglected bio after further education and am also enjoying the learning of a new area in later days



Jerel could tell us in a few words, but that simply would not be right, some direction would be nice though

I apologise if this was covered earlier in the tread.

edit: another usefull article
http://aem.asm.org/cgi/reprint/62/12/4641

["Umm, fish?"]

How long is eventually?

No real clue, but the consensus seems to be 4-5 years, if the sand bed fails at all.

Firstly, I am lazy, and I hate water changes. I am absolutely dead serious here. Frequent Wasting will cause a "continuous water change" to occur automaticaly, and forever. For me that is a very nice feature. "Continuous water changes" are 74% as effecient as monthly water changes of the same monthly volume, and that is good enough for me. At the 1 pint per day for my system, that is equivalent to a 17% water change monthly. I highly prefer this continuous condition to "all at once" water changing.

Me, too. I putting overflow drains on my sump. So, a water change is turning off the auto top-up and turning a valve. The WC water displaces old water out of the sump. I stole that idea out of Calfo's book.

I like the idea of stretching the bacterial populations. That's good.

>>>Thirdly, this process will be "effectively continuous", which eliminates concerns about "what happened when I wasted the plenun". There is no "when I wasted the plenum", because I am "always wasting the plenum".

Right, but what if the bacteria population needs recovery time? I have no idea, personally. Time will tell, I guess.

Are you going to run an O2 or pH probe down into the bed to check O2 levels? Or do I remember a discussion about this earlier. It all gets a bit fuzzy....


Cheers!

Andy

[barryhc]

Originally posted by reefclown
Barry, how far have you considered the possibility of biofilms that coat every available surface area in the tank, i,e the entire cycle occurs within a microns layer on every availabe surface regardless of the presence of 'sediment zones'

here's a random sulphur based extract that demonstrates the concept, there are millions of accredited marine biofilm articles out there.

http://aem.asm.org/cgi/content/full/65/11/5107

Within a "microns layer", what is that?

This is from reading in the link that you supplied:

FIG. 1. A cross section made with a cryomicrotome (20 µm thick) of an aerobic domestic wastewater biofilm. The biofilm thickness is approximately 1,000 µm. ( 1000 microns )

That is 1mm thick, which is .039". This is a bit thicker than 1/32".

1mm is the thickness that I stated previously regarding the "low oxygen" zone. This value is considered to be valid, in "oolitic" sand, and would be considerably thicker in a larger particle size of substrate.

I do not have any visible bio-films in my tank that are thick enough to see. This may be because of the brittle stars, and snail and crab populations. I get an exceedingly thin film on the glass after about 2 weeks, but since I clean the glass weekly . . . .

My live rock has coraline and feather dusters, and otherwise looks like "cooked rock". Same condition for 6 months. I don't stir, I don't vacuum, I don't siphon. I have proper aquascaping, 25 x flow, and skimming.

i.e. do you accept that biofilms coat every surface and in themselves are capable of completing the full nitrogen/sulfur//phosphate/e.t.c cycle at the micron level?

No, not at the "micron level". I deal in "tenths of a thousandth" everyday, which translates to 2.5 µm. I am INTIMATELY FAMILIAR with these "distances". One of your hairs is 90 microns thick, OK?

Isn't all that remains a method of gettind the most detritus out of system before it has chance to cycle in the biofilms??

No, detritus does not just cycle in the "bio-films', it creates them.
Don't allow detritus to collect in your system, REGARDLESS OF "BOTTOM TREATMENT"!!!!!!!!!

Read the first post in this thread, right on page 1 of coursre. This thread is for those who WANT TO RUN SUBSTRATE IN THEIR SYSTEM FOR WHATEVER REASON ! ! ! ! ! ! ! ! ! ! ! ! ! !

I don't mind that much if you are happy with BB. They are fine in very many cases, however, PLEASE read all of page 1, and the last two pages of this thread, if you expect to offer meaningful comments.

> barryhc

["Umm, fish?"]

I'm sorry, but I must take us a little off-topic (and we are trying to avoid that).

I don't understand why BB tank people use live rock. So many make the argument that sand beds are mysteries and therefore they don't want them in the tank. Isn't the live rock a mystery, too? Wouldn't bare egg crate shelves serve the philosophy a bit better?

Okay, rant off. No more.

[reefclown]

Barry,
firstly my apologies for not having read the thread, having now read it I can see why your response is somewhat hostile.

No, not at the "micron level". I deal in "tenths of a thousandth" everyday, which translates to 2.5 µm. I am INTIMATELY FAMILIAR with these "distances". One of your hairs is 90 microns thick, OK

Barry, I'm not questioning your familiarity with distances!

In the context of this tread my last statement was insenstive/unconstructive as was any implied reference to BB, please disregard.

OK, hopefully misunderstanding cleared up and we are on a CLEAN SLATE.
----------------------------------------------------------------------------------
Now, let me attempt to rephrase what I was meaning to ask.

The thread appears to be evaluating a method of controlling bacterial activity within a sediment layer. And the core of the discussion looks at the effects of bacterial activity within that sediment under varying circumstances.

I was simply meaning to ask what activity you believe occurs at a smaller scale, for example on the bacterial film that coats a single grain of sand. Is this bacterial film capable of completing the full nitrogen cycle. i.e does the bacterial film covering the grain of sand contain aerobic, anoxic and anaerobic zones/bacteria within it?

I'm simply asking you to consider a lower denominator, as it may aid in the understanding of how the sediment will operate when the oxygen gradient changes.


from the link provided

O2 consumption took place in the upper 50 to 100 mm of the biofilm, with a rate of 0.81 6 0.13 mmol z cm22 z h21. The production of NO3 2 plus NO2 2 appeared in the same layers....
Denitrification in the layers below 150 mm ranged from 0 to 0.28 mmol z cm22 z h21, with an average of 0.11 mmol z cm22 z

in a reduced oxygen variant of the experiment (I thought you may have found this interesting as you are looking to determine the effects when changing the oxygen gradient in the sediment bed).

Incubation with reduced O2 concentration (115 mM) decreased both O2 penetration and metabolic rates.The O2 concentration reached levels of less than 20 mM on the biofilm surface and zero within 25 to 75 mm of depth. The total oxygen uptake was 0.35 6 0.07 mmol z cm22 z h21, whereas the production of NO3 2 plus NO2 2 decreased to 0.28 6 0.14 mol z cm22 z h21 (averages and 95% confidence limits for 10 different profiles, respectively). The main activity of nitrification was found at a depth of approximately 20 to 50 mm, and denitrification occurred in the deeper layers (100 to 200 mm), with an average rate of 0.10 mmol z

so in effect rather than the 1000 microns you mentioned earlier a more realistic target figure MAY be in the range 10-300 microns ? everything below 300 microns being anaerobic. Add degradable organic matter to the above equation and the nitrifying layer will reduce yet further?

The "low oxygen" zone comes below this where most processing of Nitrite to Nitrate occurs, and it is generally regarded to be only about .5 to 1mm thick. This is where "non-obligate-Anaerobic-faculative- bacteria" do Nitrate "processing. This is generally accepted fact by many "authorities" on the subject, and if it does not "sit well" with anyone, then this is where the bacterialogical discussion needs to continue!

I hope this goes someway to explaining why the above does not still well, and hopefully open up the discussion in the areas you intended.


peace

[barryhc]

Originally posted by "Umm, fish?"
No real clue, but the consensus seems to be 4-5 years, if the sand bed fails at all.

All right, that seems to be what I find as well, including the "if at all". Plenums have failed, DSBs have failed, BB systems have failed. So what. I want the sand and gravel so that the critters can live in it. I am trying to get good reliability out of it primarily, along with some processing, whatever "we" can get "reliably".

But I require it for the critters, not for "processing". I am going to have sand and gravel in my tank, FOR THE CRITTERS period!

I like the idea of stretching the bacterial populations. That's good.

A-h-h-h . . . you're getting the "stretch idea", fantastic! I must not have presnted much of this as well as I could have, because Ihave been viewing this on the basis of a "continuous-stretch" of the bacterial populations since Dec. of 2004, a long time before I started this thread.

Right, but what if the bacteria population needs recovery time? I have no idea, personally. Time will tell, I guess.

The bacteria are going to be affected by drawing water from the plenum. Water treatment facilities are getting very good at this( although some of them argue as much as reefers ). A very new "process" uses only one "vessel" and cycles between aerobic and anaerobic only ( or so they think ), which is very close to "draw water" then "wait", "draw water" then "wait".

This is in fresh water, not salt water, and they are not "exactly" the same, but . . . . . Time will tell, I'm sure!

Are you going to run an O2 or pH probe down into the bed to check O2 levels?

I would like to run O2 and/or pH probes, but my understanding is that these probes only last so long before needing cleaning and or replacement, and "servicing" the probe, would disturb the environment were trying to monitor.

I need to find out more on this. I had intended to monitor O2 and Phosphate in the effluent, and the P is still relevant to monitor here, but oxygen may change as it travels through the plenum piping and could be changed considerably if it takes two days for plenum water to actually exit the end of the plenum piping. This might be the case depending on the volume of the plenum piping, even while the "draw"remains "high flow" and "short duration" ( like 5 seconds).

You know, as I'm writing this, I'm wondering about a DIY "water extractor", that would at least let us get a representative "sample" of the water, to test "outside" of the tank, as usual. It could be made from 1/4" I.D. PVC by 1" long, capped, and plumbed with 1/8" I.D. tubing, then run outside of the tank. This would be constructed like a little "micro plenum". Several of these, say, one for every inch of substrate depth, could be installed, along with the plenum, and drawn from, before and after "wasting" to monitor various parameters, and fluctuations.

Please don't get me wrong here, "Fish" or anyone else. I still believe that several versions of this "wasting" idea, might be found to work well, and I'm not really opposed to other versions, but I still find the "High Frequency" type to fit my expectations thus far into the investigation. If I run into a hitch, especially with Bacteria, I'll run from it like a forest fire, but that is not what I have been finding.

"Fish", what think ye, of the "micro plenum water sampler"?

> barryhc