DIY Turbidostat?

[ButterfyBoy]

I'm interested in building a DIY turbidostat, but haven't had much luck tracking down plans or specifications on the web. I was wondering if anyone had any thoughts, schematics, or links that they would be willing to share?

Basically, I'm interested in realtime monitoring of the relative density of a phytoplankton culture, so the unit would simply need to produce a variable strength signal in direct relation to the density of the culture; it doesnt need to give a precise reading in NTU's or anything like that.

Also, I was thinking that an IR diode might be a convenient source for the unit, but does anyone know whether IR frequencies will be adsorbed or scattered by common phytos, or will they simply pass through at common densities? What wavelengths / light sources would be suited to an application like this?

Any light anyone can shed on this would be much appreciated. Thanks.

[rsman]

what is it you are trying to do exactly???

do you wanna know how much phyto you have, or work a device when the phyto is high or low in concentration or both

i have a combination of the 2 going in 1 unit, the "guage" is not really acurate, but its good enuf

I use the flor lights that light my phyto
i bought a photocell that matches "normal room light"
then its just a matter of adjusting a "0" and a "100%" and anywhere in the middle so you can make the gauge or device work

[ButterfyBoy]

I use the flor lights that light my phyto
i bought a photocell that matches "normal room light"
then its just a matter of adjusting a "0" and a "100%" and anywhere in the middle so you can make the gauge or device work

That's such an obvious, tidy, and clean solution to the problem that I feel really stupid, now It should work fine for what I want.

what is it you are trying to do exactly???

Basically, I'm just interested in doing a little experimentation with a continuous culture. I'm planning to build a phyto reactor that uses a dual channel peristaltic pump to harvest phyto and replenish media in an on-the-fly fashion rather than on a batch basis. Basically, I plan to keep a fixed volume of media with a fixed nutrient content, and regulate the phyto by extracting surplus production.

My reasoning is more or less that if you draw off a small amount of the culture regularly rather than, say, 3/4ths of it occasionally, the overall biomass is so much higher that you should get a faster production rate. Well, that and i'm lazy .

At any rate, what I want the turbidostat for is to control the rate at which the peristaltic harvests the algae. I want to drain off just enough phyto to keep it at the peak growth phase just before it hits plateau, when analysis has shown its nutritional quality is greatest and at the same time I have almost the highest possible culture density. It'll take a few trys to get the system calibrated, but after that it should remain pretty stable I think, provided I can keep the system suitably abiotic to prevent crashes, and I have a few ideas on how to do that.

Thanks for the idea, rsman!

[rsman]

your not far from what I have been doing from some time, instead of collecting by densitie, I have that fixed, and vary the amount of fertalizer, also provide one last "pass" infront of light to consume any left over fertilizer.

it works well, there are some issues, but not many.
i use an RC plane propeller to move algae
i feed co2 from the bottom of what could be called a closed loop at a slow rate (1 bubble /sec)
currently my cultue unit is square, i am fixing to make this either 6" or 8" diameter 6' tall tubes fairly soon.
i have used flor and halogen lights both worked very well, but provided too much heat.


id like to know what other ideas you have if your willing to share

[ButterfyBoy]

Is there a particular reason you want to swap out your square unit with cylinders? I've actually been debating that question myself and was leaning towards going with a square one since that seemed like it would be easier to attach fittings and such to (the particular cylindrical tanks I was looking at as an alternative are .04" fiberglass, too thin to tap threaded fitting into). As an alternative, I was considering trying to build a bio-fence type system such as those made by Cellpharm (have a link for that somewhere, but can't find it right now, will post it later).

The overall idea I was playing with came from a concept I was working on for a large scale aquaculture project which would concievably consume at least several hundred gallons of phyto culture daily. The overall idea was to keep operating costs low, and since labor is a major cost, I wanted as fully automated a culture system as possible.

As I see it, continuous culture is the easiest to automate and the least labor intensive, but it's prone to crashing because of contamination and pollution. That was going to be a particular problem because I knew I wanted to operate the unit on a closed loop with the tank water. That is, instead of making up new water with the culture media, growing the phyto, dumping the water into the system, then throwing away an equal amount of the system water to keep the level stable, I wanted to use water already in the system. So mostly I was concentrating on ideas to ensure that the reactor remains abiotic to avoid crashes. It's a little complicated to describe, so I'll see if I can't whip up a few renderings of exactly how the system would work and post them here later tonight. I'd be interested to hear your feedback.

[rsman]

Is there a particular reason you want to swap out your square unit with cylinders?

well i spent some time debating it origionally also in no real order
*expandibility adding on for me now would cost a forutune
*lighting in a cylinder one can use 1 NO bulb per cylinder with less dark spaces with square you have to "play" around with multiple lights to keep the corners from being dark
*a much taller unit with a larger "face" towards the lights
*butyrate tubing works and is cheap.

the bigger setups use horazontally aligned tubes with vertically aligned NO bulbs the phyto flows in a zig zag motion the longer i can keep the co2 in the culture the more it absorbs which means the less i have to use.

I've actually been debating that question myself and was leaning towards going with a square one since that seemed like it would be easier to attach fittings and such to (the particular cylindrical tanks I was looking at as an alternative are .04" fiberglass, too thin to tap threaded fitting into).

round means you can use standard pvc without special "fittings" saves labor in building, less parts to break, less parts to buy

As an alternative, I was considering trying to build a bio-fence type system such as those made by Cellpharm (have a link for that somewhere, but can't find it right now, will post it later).

http://www.biosynthesis.co.uk/

and that is one of the things I am really really considering but DIY, i have the place to put 6 4X6 or 4X8 pannels


The overall idea I was playing with came from a concept I was working on for a large scale aquaculture project which would concievably consume at least several hundred gallons of phyto culture daily. The overall idea was to keep operating costs low, and since labor is a major cost, I wanted as fully automated a culture system as possible.

I hate the labor i like to let electronics do the job for me

As I see it, continuous culture is the easiest to automate and the least labor intensive, but it's prone to crashing because of contamination and pollution.

yea there are some things like micron filters and drum filters and other wierd things that can help but most IME kill a good % of the good stuff.

That was going to be a particular problem because I knew I wanted to operate the unit on a closed loop with the tank water.

from time to time I do this, i have a reactor setup to clean the tank water, and i dont feed as much nitrogen/phosphate fertalizers to make up the diff. look up how to build a H2O2 reactor, it works really nice, and is easy to make 100% automatic and kills anything that goes into it.

That is, instead of making up new water with the culture media, growing the phyto, dumping the water into the system, then throwing away an equal amount of the system water to keep the level stable, I wanted to use water already in the system. So mostly I was concentrating on ideas to ensure that the reactor remains abiotic to avoid crashes. It's a little complicated to describe, so I'll see if I can't whip up a few renderings of exactly how the system would work and post them here later tonight. I'd be interested to hear your feedback.

me to

[ButterfyBoy]

Well, in attempting to render out some design ideas as suggested, I stumbled across a few flaws in the design I had in mind. Turns out that two pieces of equipment can't occupy the same space at the same time . So I'll have to revise that a little before I complete the schematic. But at least the process was helpful.

look up how to build a H2O2 reactor, it works really nice, and is easy to make 100% automatic and kills anything that goes into it.

When I was toying around with building the larger system, I was thinking about using a batch chlorination / dechlorination system to do the same job. For the smaller system I'm toying with now (sort of a prototype, as it were) I'm thinking of simply using UV at a zap dose of ~1.2million microwatts/cm^2/second, which is many times the kill dose of any competitors I can imagine (the most resistant algae have kill doses in the range of 30-35,000 microwatts/cm^2/sec). I have a few spare sterilizers that are more than capable of delivering that kind of dose at the flow rates i'd be using.

round means you can use standard pvc without special "fittings" saves labor in building, less parts to break, less parts to buy

I was avoiding PVC because of the cost. See, I was kind of thinking of building my reactor "inside-out" as it were: using a large diameter reactor, 12-18", and placing the flo. bulb sheathed within the center of the reactor (imagine the way that a UV bulb is positioned in a UV sterilizer). I figured this would light the culture more evenly and make more efficient use of the way flo. bulbs generate light in a 360 arc. 12-18" PVC is cost prohibitive, especially if you want it translucent.

http://www.biosynthesis.co.uk/

That's exactly the one I had in mind. What do you think about their claim that the algae needs a dark period to fully synthesize some of the more complex compounds? I seem to remember something from HS biology about that being true for higher plants, but I don't know about for algae. It certainly doesnt seem to mesh with what most aquarists do with their cultures.

Thanks for your time and assistance on this, rsman

[rsman]

Well, in attempting to render out some design ideas as suggested, I stumbled across a few flaws in the design I had in mind. Turns out that two pieces of equipment can't occupy the same space at the same time . So I'll have to revise that a little before I complete the schematic. But at least the process was helpful.

yea i mean you should be able to have 2 or 3 things take up the same space, too bad you cant

When I was toying around with building the larger system, I was thinking about using a batch chlorination / dechlorination system to do the same job. For the smaller system I'm toying with now (sort of a prototype, as it were) I'm thinking of simply using UV at a zap dose of ~1.2million microwatts/cm^2/second, which is many times the kill dose of any competitors I can imagine (the most resistant algae have kill doses in the range of 30-35,000 microwatts/cm^2/sec). I have a few spare sterilizers that are more than capable of delivering that kind of dose at the flow rates i'd be using.

UV and me are on iffy terms but dont forget you have to kill bacterias and any pods also, not just algaes ive seen the numbers for things like rotifers I just dont recall them, a H2O2 reactor isnt much more than just a UV on steroids anyways.

I was avoiding PVC because of the cost. See, I was kind of thinking of building my reactor "inside-out" as it were: using a large diameter reactor, 12-18", and placing the flo. bulb sheathed within the center of the reactor (imagine the way that a UV bulb is positioned in a UV sterilizer). I figured this would light the culture more evenly and make more efficient use of the way flo. bulbs generate light in a 360 arc. 12-18" PVC is cost prohibitive, especially if you want it translucent.

well IF you went by the bio-fence dudad you would be using 2-4" pvc just lots of it and the butyrate tubing is quite cheap the inside out way does work but it forces you to light 100% of your algae, the bio-fence allows you to put either all or part of it outside to use the sun i currently maintain 2 cultures of nano, 1 in the garage where i do most of my breeding and another in my bedroom where I have dwarf seahorses, my garage setup is setup with halogen lights across the top and flor lights installed inside the algae the culture tank is square and ive installed acrylic tubes that the NO and PC bulbs fit into its 50 gallons of nano 20 iso 20 tet. the one in the bedroom has a PC light bulb and thats it. and its 12 gallons.


my thought was to replace the bedroom one with one resembling

http://www.fao.org/DOCREP/003/W3732E...uous%20culture

figure 2.10/2.11


ive also considered a box shaped kinda spiraled bio fence like creature wraped around tubes like above.

and to add onto the garage one one or more DIY bio-fence units making the garage portion the "dark" portion


That's exactly the one I had in mind. What do you think about their claim that the algae needs a dark period to fully synthesize some of the more complex compounds? I seem to remember something from HS biology about that being true for higher plants, but I don't know about for algae. It certainly doesnt seem to mesh with what most aquarists do with their cultures.


micro algaes need the off light time. nothing personal to anyone else reading this but have you seen some of the "hobbiest" cultures, its like there happy they have green tea, forget that i want thick high densitie algae. though most of what I hear about on 24/7 are some of the macroalgaes and its to keep it from going sexual. however I thought most of the hobbiest micro algae's are on a 16/8 light timer.

Thanks for your time and assistance on this, rsman

its fun to chat with someone who knows things about algae, and wants to chat about it I find that those that know about it dont wanna spend any more time chatting or dont wanna be in trouble for giving away any "trade secrets" exchange of ideas will make this hobby even more fun

[bstreib]

Hi ButterfyBoy,

I was experimenting with a homebrew colorimeter that may have some application as your "turbidostat". My application was for a coarse water quality assessment during water changes. Basically it consisted of certain color frequency photo diode and 2 coresponding photo detectors. One receptors was placed 180 degrees across the pipe from the transmitter and the other 90 degrees from it. The outputs of the recievers were fed into a simple out amp the and measured with a meter. One receiver measures the transmitivity of the fluid and the other reflectivity.

A simple LED can be turned into a photo detector by sanding the end of it flat and smooth. LED are available in a variety of colors and all have a fairly narrow spectrum of transmission and reception. So using green LED's as the density of the phyto increases the the transmitivity decreases [absorbtion increases]. Actual trigger points would be verified by microscopic examination. The rest of the control circuitry is straight forward.
Hope this helps.

[ButterfyBoy]

bstreib

That's an interesting idea. I know that there are systems available for commercial / laboratory use that monitor the adsorbtion wavelengths of chlorophyl-a and use that to determine the total amount of primary production. Seems like your idea works in a similar kind of way.


rsman

I'll definitely take a look at some H2O2 reactors.

The thing that really appeals to me about the biofence / tubular reactor design is the way in which it allows (assuming you light it artificially) both the dark period and the light period to be provided simultaneously. It seems to me that that would be the best way to limit severe O2/CO2 concentration fluctuations, which I expect would contribute significantly to culture crashes. There would still be some flux, since I don't imagine you'd have the same amount of algae in the dark as you did in the light at all times, but the more stability, the better.

Do you know anything about what the minimum light cycle times might be? I understand that it takes a while for the photosynthesis process to ramp up / ramp down. Even operating at a pretty low continuous flow, it seems like it would take a pretty big reactor to provide 16 hrs of light and 8 hrs of dark. I was wondering if a faster cycle, like 2 hrs light / 1 hr dark would allow for the same rate of production. Overall, the total hours of light vs. dark are the same as 16/8, but is the algae efficient enough at shifting photosynthetic gears to take maximum advantage of the shorter bursts of illumination?

How dense do you manage to get your cultures at the moment, and how much light penetration do you manage to get from the NO flo.s that you use?

Also, does anyone happen to know what the lux output of a 48" 40w T12 NO or a 48" 32w T8 NO is right up near the surface of the bulb? One of the reactors I'm toying with is similar to a tubular (but a square system a bit like the one you suggest, rsman), and it's pretty compact, with bulbs sandwiched between reactor panels. I'm a little concerned with the possibility of photo-inhibition if I dump too much light in.

Who knew algae growing could get so complex? Back in my LFS days, probably 1 in 5 questions was about how someone could stop their water going green... and here we are theorizing about the most efficient way to *make* water green

[rsman]

I'll definitely take a look at some H2O2 reactors.

i was vague on why i like them, here is a very quick description of what happens, course filtered water goes into a chamber where .0003% or less hydrogen peroxide and a tad of co2 is added. the chamber mixes the 3 up, and passes it thru a UV bulb. the co2 keeps any calcium from forming on the bulb by lowering the PH, it also supplies high co2 water to your algae it doesnt take away from you haveing to add co2 to get high densities but it sure does help. by not adding low co2 water at volumes daily

The thing that really appeals to me about the biofence / tubular reactor design is the way in which it allows (assuming you light it artificially) both the dark period and the light period to be provided simultaneously. It seems to me that that would be the best way to limit severe O2/CO2 concentration fluctuations, which I expect would contribute significantly to culture crashes. There would still be some flux, since I don't imagine you'd have the same amount of algae in the dark as you did in the light at all times, but the more stability, the better.

there are several parts of this system I like, ive tossed around with many minor concepts including an artificially lighted tank while the pannels are in the dark (night time) just reversing which part has the light and which part does not. depending on the turn over and what you did around sunrise/sunset the algae might not know the difference, just some more things to ponder . last night I also considered some of the cost at least the tube fence part of such a unit, a 3' high and 6' wide the cost of the plumbing will be aprox(havent worked in any volume discounts that this does qualify for) $102 using 2.75" od tubing holding 21 gallons a little steep but not really so bad. the next step down was $102 also holding 19 gallons at 2.5" the next up was $156 for 3" at 22 gallons

Do you know anything about what the minimum light cycle times might be? I understand that it takes a while for the photosynthesis process to ramp up / ramp down. Even operating at a pretty low continuous flow, it seems like it would take a pretty big reactor to provide 16 hrs of light and 8 hrs of dark. I was wondering if a faster cycle, like 2 hrs light / 1 hr dark would allow for the same rate of production. Overall, the total hours of light vs. dark are the same as 16/8, but is the algae efficient enough at shifting photosynthetic gears to take maximum advantage of the shorter bursts of illumination?

ive read that a 4/1 cycle does produce nice results i just dont remember where and if it was a very reliable source. the bio fence uses a faster flow and some magic cleaning beads to reduce the need for cleaning, so id suspect they do something like the 4/1 cycle +- a few

How dense do you manage to get your cultures at the moment, and how much light penetration do you manage to get from the NO flo.s that you use?

ive actually stoped measuring ive found i get higher densities when i dont try to micromanage the algae i dug out my measuring stick and stuck it in bleach ill test both tonight and report the results. I do check every now and then for contaminants and find none

the NO's are kinda a quick fix to not enough light back when I didnt know what I know now they are close enough to the lower portion of the tank that there proximity makes up for the lack of penitration.

Also, does anyone happen to know what the lux output of a 48" 40w T12 NO or a 48" 32w T8 NO is right up near the surface of the bulb? One of the reactors I'm toying with is similar to a tubular (but a square system a bit like the one you suggest, rsman), and it's pretty compact, with bulbs sandwiched between reactor panels. I'm a little concerned with the possibility of photo-inhibition if I dump too much light in.

I dont know the output for those bulbs, I am sure i can find them when i post later tonight if its not posted ill post them then.

Who knew algae growing could get so complex? Back in my LFS days, probably 1 in 5 questions was about how someone could stop their water going green... and here we are theorizing about the most efficient way to *make* water green

yea but its fun now

[rsman]

darn let this thread escape

first acording to the PCM "by setting the spectrophotometer at 750 nm". though I used the regular lights, it might be better to use a 750 nm light source.

also Ive built 2 of the bio fence look alikes, both different in path one takes a right to left path split between every tube, and another takes a zig zag path back and forth across the field.

I also dont have access to the magic cleaning beads so the test will probibly be which clogs first.

I crashed my bedroom culture but kinda knew it was coming. still have the larger garage culture the DIY fence will be connected to the bedroom culture. i guess a smart person would have stoped the culture while toying with the container, but thats history now