Fluidized Sand Bed Help

[jamiep]

Originally posted by m2434


X amount of waste -> produces Y amount of ammonia -> Q amount of nitrite -> produces Z amount of nitrate

So, the rate limiting step is waste and ammonia. Therefore, to end up with less nitrate, we need less waste, less ammonia/nitrite or need to convert nitrate to something else like nitrogen gas. It's very possible I'm missing something, but I just don't get how you can convert ammonia “too fast”. What's worse, excess ammonia or excess nitrate?

Yes origionally I was going to post this

I think the point is that there is a backlog of Nitrate. If for example it would take 1day to process one unit of ammonia, it may take 7days to process nitrate to Nitrogen so if one unit of ammonia was produced a day, after seven days there would be 6units of Nitrate (7units produced but only one processed in 7days)

But then I realised that the system would just produce more nitrate procesing specific bacteria, and that at most it would only be 6units behind, so ammonia must be the limiting factor!

Answering your retorical questions Amonnia is worse.

At the end of the day, we don't want either though so the fundimentals are the same, regular water changes and regular cleaning for filters, sand beds or blowing detrus of rocks!

Jp

[Paul B]

Thats why I said the best system is a trickle filter with enough live rock. It is good to convert ammonia to nitrate, it has to be done to have a working system. I had a trickle filter for 25 years. My nitrate was always around 15 or 20. There is no problem with that but in a reef it is better if a filter converts the ammonia and eliminates the nitrate at the same time. Of course we don't want ammonia at all but it seems that live rock alone, providing there is enough of it will convert the ammonia and eliminate the nitrate at the same time. I always said that a trickle filter is the best filter for a fish only tank because ammonia is the main polutant with fish.
With a trickle filter alone the water will have to be changed more often because there is no place for the nitrates to be converted.
I myself use a reverse UG filter run very slow. I think I invented this system and for about 30 years my reef has been stable with almost no nitrate. I think I have the best of both worlds. My RUGF also converts nitrate to nitrogen gas as I can see it being expelled if I turn off the pumps for a while. I stated that wet drys are too clean. In a RUGF run slow, the interfaces of the gravel will become anoxic on a tiny scale. This will not happen at first when the gravel is very clean but as the mating surfaces of the gravel build up detritus and accumulated bacteria, de nitrification will begin. If the RUGF is run fast, this will not happen or the gravel will become clogged and nothing will happen.
M2434, you are correct in your regard of your formula's but you diden't figure "time" in your post. A trickle filter will convert ammonia very fast, which as I said is a good thing.
If we could get a dinitrification filter to work as fast we would have no problems at all.
Of course this is all conjecture on my part as I am not a chemist or researcher but I do have a very old tank to experiment on and learn from.
Have a great day.
Paul

[m2434]

- Thanks Paul, I see what you are saying now. Your RUGF could certainly have some potential - I might have to look into this further.

- jamiep, great advice! I'd never argue with good husbandry.

[jamiep]

Would a slow run FSB then not give the same effect? Or using the same unit keeping partical size slightly bigger even. This would give a very large depth of sand possible in your FSB and hence a long time for water to leave the contact medium even with a slow flow!

Paul in you RUGF are you using gravel, live sand, coral sand, very small live rubble or what?

[WaterKeeper]

Retiring in two weeks huh. I thought old sailors never die they just sink away. God, I haven't been out to L.I. since my uncle died about 15 years ago.

As far as denitrification goes Randy had a theory that the two process, nitrification and denitrification, must occur in close proximity of each other. In aerobic filters only the nitrification stage occurs and the nitrates enter the water column. There they are less likely to be denitrified than if they had denitrification occurring right next door. Actually it doesn't take any specialized bacteria to denitrify. Many aerobic bacteria are also facultative anaerobes meaning they can convert to anaerobic conditions when oxygen is depleted. However, if highly oxidized materials, such as nitrate, are present they can take the oxygen from those molecules and use it instead of free oxygen.

Now things get a little more complicated at this point. The amount of nitrogen entering the tank in the form of proteins, amino acids, and other nitrogen containing compound is dependent on the amount of food supplied. Food is consumed and ammonia is produced then converted to nitrite and nitrate. In any tank there should be a mass balance between nitrogen in added food and nitrate produced. Yet people still complain that mechanically assisted biofilters are "nitrate factories".

I proposed that perhaps they can produce more nitrate than what food supplies by the process of nitrogen fixation, where atmospheric nitrogen gas is converted to ammonia and nitrate. Cyanobacteria are examples of microorganisms that can fix nitrogen. It may be that growth of nitrogen fixing organisms takes place more readily on mechanically assisted biofilter than on natural biofilter like LR. This would lead to higher nitrogen import than export in the marine tank.

I think I just forgot I'm writing this in the Newbie Forum.

[m2434]

Nitrogen fixation... very interesting. Unfortunately, we may have reached our quota for scaring off newbies this week
I'll have to think about that while I'm away this weekend.

[capn_hylinur]

an excellent read guys--apppreciated

if its too technical don't worry about the mods moving the thread cause one or two of them are participants--LOL

[capn_hylinur]

reading through the above posts---is it safe to say that live rock and substrate are all the biological filtration you need?

[Paul B]

Your RUGF could certainly have some potential -

M2434, yes but as far as I can tell they may only work for 37 years, I have no experience longer than that

My RUGF uses dolomite gravel which is like crushed coral (kind of) the grain size is about the size of rice.

I doubt a fluidized sand filter run slow would give any benefit. It is designed to keep the sand in a state of flux and there will be no anerobic conditions to convert nitrate.

Waterkeeper, you must have paid attention in school.
I am retiring a week from thursday. I am taking that next friday off. What are they going to do? Fire me!

[hugodboss]

wow that was great info. that wouldnt scare me off im hooked on this hobby..lol

[daveverdo]

How is the RUGF implemented?

I have been reading through this and other posts regarding RUGF and still have some questions. I understand the concept but not the implementation. That is, how should someone set one up.

Do you use a section of the sump? A seperate tank? What size compared to the main tank?

I have been running marine tanks on and off for over thirty years. I had a UGF in my 30g for years. For a while in the early days instead of vacuuming the gravel I used to clean the dolomite substrate by taking out the fish setting up a canister filter and reversing the flow through the UGF. What a mess. I always pondered the idea of a permenent RUGF but have never actually read about anyone actually doing it.

I just moved and am setting up a new 90g with a sump in the basement. What would be a good plan of action if I wanted to try a RUGF? I am still in the planning stages so my design is a blank slate.

Teach me!

Dave

[capn_hylinur]

Originally posted by daveverdo
How is the RUGF implemented?

I have been reading through this and other posts regarding RUGF and still have some questions. I understand the concept but not the implementation. That is, how should someone set one up.

Do you use a section of the sump? A seperate tank? What size compared to the main tank?

I have been running marine tanks on and off for over thirty years. I had a UGF in my 30g for years. For a while in the early days instead of vacuuming the gravel I used to clean the dolomite substrate by taking out the fish setting up a canister filter and reversing the flow through the UGF. What a mess. I always pondered the idea of a permenent RUGF but have never actually read about anyone actually doing it.

I just moved and am setting up a new 90g with a sump in the basement. What would be a good plan of action if I wanted to try a RUGF? I am still in the planning stages so my design is a blank slate.

Teach me!

Dave

I might have missed something here--but I think the discussion was around setting up a fluidized sand bed filter as a reverse filter?
I am interested in the answer to this too

[Paul B]

Capn, you diden't miss anything, I think the thread was about a fluidized sand filter but since Dave asked me about a RUGF I can quickly tell him. Every one else just don't read this post as I am the only one on here who would have a RUGF anyway.
Talk amongst yourselves for a minute.



Dave it is a regular UG filter but instead of running it the way the instructions tell you, just put a small powerhead on the "UP lift" tube and run the water down the tube so it goes under the gravel. It should be run as slow as possable, mine is 50 GPH down each tube. You also need a filter like a sponge on the intake so you don't push detritus down the tube. I have three tubes so I plumbed all of them together and brought them into a small container above the water. I pump water into the container with one pump and the water is evenly distributed to all three undergravel plates. With this system I had to clean under the plates after the first 25 years which seemed fine for me.
I don't have a picture of the set up anymore but here is my tank with the front wall open, you can see a tube coming out of the water on the right side. That is the tube which pumps water into the container which you can just about see. There is a sponge just at the top of the water which I rinse weekly.

[WaterKeeper]

What Paul meant to say--

Originally posted by Paul B
as I am the only one in the world who would have a RUGF anyway.
Talk amongst yourselves for a minute.

[Paul B]

Waterleaker, I have amphipods older than many of the members here in spite of that RUGF.

And I have socks older than Waterkeeper

[m2434]

Okay, I'm back,

As to reverse fluidized bed filtration, I have not researched this and I doubt any research in this area exists. I would guess that a single FBF would not have enough volume to filter out O2, allowing anaerobic conditions and still provide a large surface area for the bacterial colonization. However, I would guess that it may be possible to string multiple filters together and achieve this goal... Of course, I can't claim it would last 37 years

As to nitrogen fixation, it looks like the only problem is that nitrogenase is inhibited by O2. As a consequence, nitrogen fixing organisms tend to have fairly low tolerance for O2. Therefore, it's unclear to me if these organisms would be active under highly aerobic conditions such as a trickle filter... however, this being said, I did find some possible leads.

As reviewed by Gruber N. (2005) there doesn't appear to be a mass balance of nitrogen in the upper ocean either and Gruben suggests nitrogen fixation by Trichodesmium, may be the source of the extra nitrogen. Trichodesmium is photosynthetic and therefore must be protected somehow from produced O2. Interestingly, as it turns out, although Trichodesmium single celled cyanobacterium, they are colonial in nature and form trichomes (filaments hair like structures). Berman-Frank et al. (2001) showed that within these structures, individual cells could modulate oxygen production and consumption, throughout the photo- period and therefore this mechanism may provide temporal and spatial protection against O2 production (Berman-Frank 2001). Unfortunately, it is unclear whether or not they may also be protected from O2 diffusion from high concentrations of extracellular O2.

However, there are other possibilities as well, Ribbe et al. (1997) examined the bacterium S. thermoautotrophicus, which links N2 fixation with the oxidation of superoxide. They concluded that, as a result of the unique mechanisms, S. thermoautotrophicus is "absolutely O2-insensitive". So although, nitrogenase, is inhibited by O2, there is certainly evidence for a number of protective mechanisms and WaterKeeper's hypothesis is certainly feasible.

So, WaterKeeper, I guess you can keep your job at least for another week..


Berman-Frank I, Lundgren P, Chen YB, Küpper H, Kolber Z, Bergman B, Falkowski P.
Segregation of nitrogen fixation and oxygenic photosynthesis in the marine cyanobacterium Trichodesmium.
Science. 2001 Nov 16;294(5546):1534-7.

Gruber N.
Oceanography: a bigger nitrogen fix.
Nature. 2005 Aug 11;436(7052):786-7.

Ribbe M, Gadkari D, Meyer O. N2 fixation by Streptomyces thermoautotrophicus involves a molybdenum-dinitrogenase and a manganese-superoxide oxidoreductase that couple N2 reduction to the oxidation of superoxide produced from O2 by a molybdenum-CO dehydrogenase. J Biol Chem. 1997 Oct 17;272(42):26627-33.

[Avi]

What does all this mean in the lingua franca....reefing English?

[m2434]

Originally posted by Avi
What does all this mean in the lingua franca....reefing English?

Okay, very brief summary of the “random” thread of the month..
(This is my interpretation - if someone disagrees please correct me)


1)A fluidized bed filter is a device where water is run through a column of sand, from the bottom up. This results in a lifting of the sand up so that it is sort of “floating” in the tube. However, the flow must be such that the sand lifts up, but does not lift up enough to be expelled into the tank.
2)A reverse under-gravel filter is similar, but has lower flow, this does not lift the sand and distributes the flow over a larger volume. The surface of the sand becomes matted due to detritus accumulation and is sealed off – this allows small anaerobic pockets under the surface for denitrification.
3)Live rock, live sand, and RUGF's may process nitrate as well as ammonia/nitrite - trickle filters and FBFs do not
4)Some people claim that trickle filters are “nitrate factories” and produce excess nitrate.
5)The amount of nitrate produced should depend on the amount of ammonia/nitrite in the system.
6)Excess ammonia/nitrite could occur if waste is deposited in the filter and not consumed, allowing additional break-down of organic waste and with enough accumulation, these systems may start to leach nitrates.
7)FBF in theory may not be prone to this due to their design (if this is the reason), because the sand is always in motion, bumping around and keeping a bio-film from accumulating (assuming there is a good pre-filter to prevent large chunks of waste from entering in the first-place..
8)If there is limited ammonia/nitrite, some organisms can convert atmospheric nitrogen to ammonia/nitrite (fixation) and could then produce extra nitrate.
9)Waterkeeper suggested that this might be the reason for the “nitrate factory” observation.
10) The enzyme required for nitrogen fixation does not work in the presence of oxygen.
11)There are possible mechanisms that could allow nitrogen fixation activity in the presence of oxygen such as in a trickle filter – so Waterkeepers hypothesis can't be ruled out and is feasible, but right now, no one really knows.
12) It is unclear if either trickle filtration of FBFs are better than the other.
13) The methods capable of denitrification should be more robust than either
14) It is debatable whether or not trickle filters or FBFs are necessary.

[Avi]

Thanks for going to the trouble of explaining...this is something that is always lurking out there and this, it seems to me, is now THE place to come for a digest of what's chatted about all the time.

[Cheekmonkey]

Haha I hope this doesnt stop this is a good read, but educationally and entertainment wise.

[Skepperz]

A fluidized bed filter can be bad system if the power goes off for to long, the bad effluent gets pumped back into the system when the pwr gets turned bk on, just what i have been told. I don't know the science behind it tho, it got something to do with the dead bacteria??

[Paul B]

Quote
"Gruben suggests nitrogen fixation by Trichodesmium, may be the source of the extra nitrogen. Trichodesmium is photosynthetic and therefore must be protected somehow from produced O2. Interestingly, as it turns out, although Trichodesmium single celled cyanobacterium, they are colonial in nature and form trichomes (filaments hair like algae) may provide temporal and spatial protection against O2 production (1997) examined the bacterium S. thermoautotrophicus, which links N2 fixation with the oxidation of superoxide. Segregation of nitrogen fixation and oxygenic photosynthesis in the marine cyanobacterium Trichodesmium.Ribbe M, Gadkari D, Meyer O. N2 fixation by Streptomyces thermoautotrophicus involves a molybdenum-dinitrogenase and a manganese-superoxide oxidoreductase that couple N2 reduction to the oxidation of superoxide produced from O2 by a molybdenum-CO dehydrogenase. "
Science. "

I think we should post this in the Newbe Forum just for kicks.
Beam me up Scotty.
I can see Waterkeeper getting out his dictionary even as we speak.
M2434, very good explanation and I agree with almost all of it.
Have a great day.
Paul

[m2434]

Originally posted by Paul B
I think we should post this in the Newbe Forum just for kicks.
Beam me up Scotty.

[capn_hylinur]

Originally posted by Avi
What does all this mean in the lingua franca....reefing English?

it means don't try this unless you have 37 years experience

stick to a refugium

[capn_hylinur]

Originally posted by m2434

nah--post it in the advance form and we can sit back and what those *reef nerds decipher
"nitrogen fixation by Trichodesmium"

by the way I would beam you up if I could

Scotty (aka capn_hylinur )

*reef nerds" is a term of endearment