Phytofuge - For the biology nerds out there

norskfisk

New member
Hi folks, here is a small presentation of a project I am doing. I am experimenting with using a refugium to grow plankton. I haven't seen anybody doing that before, at least not in a way that produces large measurable quantities of plankton. The basic idea is to get phytoplankton to reproduce and grow in high concentrations like in a phytoreactor. It is also possible that it can be used to grow zooplankton by dripping artemia eggs into it daily with an auto feeder. My version is mostly for azoox tanks, but with small modifications it could be used for reeftanks too. I don't know if it can be made to work, but that is what I want to test out with this small setup.

The setup consists of two 112 liters tanks. One has the role as refugium and the other as the display tank. The refugium is placed slightly higher than the display tank and overflows down into it. Since it is a test setup, only the refugium has lights. The display tank has a skimmer and chiller directly attached. There is no sump. The refugium has a CO2 dosing system, and nutrients are regularly dosed with a formula that corresponds to the Guilliard F/2 formula. The display tank has a shallow live sand bed for filtration, and hold various azoox coldwater test specimens.

The current status of the project is that it has been running for about a month, and it has been fun so far. I have had two blooms of diatoms. But I have not been able to keep satifying concentrations of algae in the refugium over time. But there are many parameters that can be changed to fix that. However I want to take my time and test one thing at a time so that I know what works and what doesn't.

I am keeping a blog over the project

Pictures:
1. The setup.
2. The refugium. Notice the white acryllic trays for easier cleaning.
3. Diatom bloom (roughly 500 million cells per liter).
4. Diatoms under microscope. Each cell is about 7 micrometers diameter.
5. After a few days of bloom the first crash came.
6. Animals. Coldwater filter animals: Sea squirts, scallops, mussels, sponges, barnacles.
7. Test display tank with sand bed and animals.
 

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norskfisk

New member
I think it is time for a little update here:

It has been 4 months since startup, and about 3 months since the majority of the animals were collected. Most of the time has
been used for experimenting with phytoplankton growth, finding how to get more stable conditions and higher concentrations.
I have also started experiementing with artemia dosing.

The project has been fairly successful so far. Some nice conclusions:
- It works very well to use plain seawater as a startup culture for phytoplankton.
- I've found out how to produce phytoplankton for weeks without crashes.
- The refugium produces far more phytoplankton than the test animals can eat.
- Artemia will hatch and grow rapidly in the refugium, and don't seem to reduce the phytoplankton concentration.

Things that could be better:
- The phytoplankton culture goes into a monoculture of small cells within two weeks.
- Concentrations never get nearly as high as in professional photobioreactors.
- Macroalgae contamination gets high within two weeks, and dirt gathers at the bottom of the refugium.
- The display tank sometimes get cloudy from phytoplankton. The skimmer performs very variably against it.

Some facts and observations:
- I use 40% daily flow through the refugium, divided into 20 one minute pumping periods.
- 24 hour lighting.
- Seachem flourish must be dosed in daily doses, not weekly. I dose 3 times per day, manually. Dosing pump would be nice.
- Phosphate seems to be used up faster than nitrate.
- pH is a challenge. The pH probe is an achilles heel. CO2 dosing should be done with a controller and daily manual inspection.

Challenges:
- Find a good combination of skimmer feed rate and perhaps UV filtering to keep a perfect concentration of plankton in
the display.
- Measure animal growth rates.
- Measure artemia feeding rates.

Some of the current display tank animals
02_animals.jpg


The feeding ring where I dose artemia daily
http://www.jonolavsakvarium.com/webpix/PProject/02_artemia01.jpg

A jar of tank water with artemia and algae
[img]http://www.jonolavsakvarium.com/webpix/PProject/02_artemia02.jpg

A bloom of tiny green algae
02_green_bloom01.jpg


Green algae creating great problems in display tank. Perhaps UV filter would stop this.
02_green_bloom02.jpg


Some of the types of micro algae I have observed in the refugium. Some bacteria can be seen, marked with red arrows. The small one next to the scale in the lower left corner is the one that bloomed in the pictures above.
02_micro01.jpg


Other types of algae that I commonly observe
02_micro02.jpg
 

wdt2000

New member
Very nice, are you using unfiltered seawater? What temperature do you keep your tanks?

Great microscope shots!!
 

Opcn

New member
I love the green tank. Don't do anything to change it, just move your favorite animals to the front. I'm sure that they love it too, and some population will rebound and fix it for you in the near future.
 

norskfisk

New member
wdt2000: Thanks! Yes, I use unfiltered seawater. The temperature in the display tank is set to the natural ocean temperature here, at the depth I want to simulate, which is roughly 5 to 16 Celsius, depending on season. The refugium is not temperature controlled. The temperature varies between 19 and 25C.
 

dave willmore

New member
I love your idea. But even under the best of conditions phyto will only double each day, whereas any planktivore that gets into your system can grow exponentially until there is no phyto left.

For example, brine shrimp batch cultures start with dense green water but once you add nauplii the water completely clears up in a few days, and brine shrimp are much slower reproducers than rotifers or copepods. One rotifer will be a million in a week and a dozen new babies each day mature in 18 hours to start making dozens of their own.

So while I wish you lots of luck I don't understand how you are keeping rotifers or other planktivores from cleaning you out. If you have figured this out I would like to be the first to congratulate your genius. I hope I am missing something.
 

norskfisk

New member
This is not an eternally stable feeding system. So far, around 3 weeks without maintenance is the best I have done. With maintenance, maybe 6 weeks, but it may not be worth it since emptying and reseeding the refugium isn't that much work. So no genius declarations ;-). But the problem has not been planktivores. I would love those to bloom since they are great food. So the scenario you talk about is not a problem, it would be a great advantage. The planktivores would disappear as soon as the food was gone and the algae would come back. Planktivores can't destroy such a system. They are washed out according to the same rules as the phytoplankton, and they reproduce more slowly. Their reproduction is controlled by the amount of phytoplankton too, they first need to eat, grow, then reproduce. They are lagging after a lot. In static cultures where large amounts of rotifiers are dosed they may be able to clean away their own food, but it is different here. Still, it would be interesting to dose some of the faster growing species of rotifiers, just to see.

The problem is macroalgae, or mats of benthic microalgae. They are efficient competitors to the planktic algae, and they don't get washed out. they do take over the refugium after a few weeks. They grow on the bottom, sides, air hoses, pH probe (grr), and form mats on the surface. If I clean the refugium bottom and sides without emptying the whole thing they bounce right back in 48 hours.

I have great confidence that this will be the system I'll use in future azoox tank. But it is possible that the stability and maintenance issues will be so many that I will be the only one using it. Still, endless amounts of live food for "free", continuously fed is worth the effort for me. It is the way to feed filter feeders.
 

Opcn

New member
Doubling daily is exponential growth.

While planktivores can boom ultimately they will reach an equlilibrium where in the concentration of food particles drops to a level where they are just as likely to starve to death or be eaten themselves before they gather enough food to have offspring of their own as they are to have offspring of their own. The paradox of plankton (more of a mystery than a paradox) also insures that there are several types of phytoplankton in sea water and this means that any one planktivore can whipe out its own food source with out eating all the phyto in the system. knocking down one variety just leaves room for other different varieties.

You should build a dark box around the pH probe to avoid algae growing on it and gumming it up.

Have you considered using any sort of snails or chitons or limpets or cowries to clean the benthic algae from your system and free up the nutrients for the phyto in suspension? Or is there not enough O2/too much CO2 to support such large (relatively speaking) animals?

I wonder what the effects of the large temperature disparity between the tanks is...
 
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dave willmore

New member
Doubling daily is exponential growth.

While planktivores can boom ultimately they will reach an equlilibrium where in the concentration of food particles drops to a level where they are just as likely to starve to death or be eaten themselves before they gather enough food to have offspring of their own as they are to have offspring of their own. The paradox of plankton (more of a mystery than a paradox) also insures that there are several types of phytoplankton in sea water and this means that any one planktivore can whipe out its own food source with out eating all the phyto in the system. knocking down one variety just leaves room for other different varieties.

You should build a dark box around the pH probe to avoid algae growing on it and gumming it up.

Have you considered using any sort of snails or chitons or limpets or cowries to clean the benthic algae from your system and free up the nutrients for the phyto in suspension? Or is there not enough O2/too much CO2 to support such large (relatively speaking) animals?

Sorry to be unclear. I meant to convey that doubling phyto would be a best case scenario, while zooplankton can multiply many times faster and would soon outgrow the food supply. Most zooplankton can eat many types of phyto and it is usually a short time before phyto is cleaned out. I like Jon's idea of continual reblooming, that is a great idea if one is near the coast.
 

norskfisk

New member
A black box around the probe is certainly worth considering. It would probably fix the problems, if I could just find/make one I am satisfied with.

I haven't really considered using snails or limpets. They would probably not have any problem with CO2/O2, but the high temperature would be a problem. I got a lot of experience with them in my algae tank, and snails wouldn't make any impact on the macro algae here. Large limpets could, but they wouldn't get all and would introduce a number of issues themselves, particularly with cleaning. Limpet shells are excellent algae refugiums. So it's not really worth the trouble.

About the temperature: Once an hour the temperature in each tank changes by 0.2C (given the difference is 10C). I don't really think it has any effect on anything. I was worried that the high temp in the refugium would be bad for coldwater micro algae, but some species definitely grow well.
 

Opcn

New member
I was thinking that your high temp refugium might be producing species of algae that will not be appropriate for your low temp critters.
 

norskfisk

New member
Here is a little bump of this thread for those who may be interested:

The project has been a great success in the sense that I can now consistently grow phytoplankton and keep it growing for months. I have grown for more than two months without reseeding or cleaning the refugium. And the reason I stopped after that was not that I couldn't have kept going. I still don't get extremely high concentrations of phytoplankton though. But it seems to be enough for the animals in the DT. So it isn't that much of an issue. I have also noticed that the concentration doesn't seem to sink when I stop adding CO2. I am hoping that CO2 addition is unnecessary. It is a PITA to keep it stable, and very expensive to buy too. So that is good news for anybody else who want to try this. Anyway, I can recommend such a setup for anyone who is dedicated to feeding animals that need large amounts of phytoplankton.

Zooplankton: I consider the phytoplankton stage done now and work only with zooplankton. The artemia experiment failed. It seemed to work when the temperature was above 25C in the refugium, but once it dropped below that they grew slower and slower. So I stopped that experiement. Instead I am now working with locally caught copepods as shown in some of the pictures below. It is not going well there so far. I manage to get them to die out slowly over a period of 3 weeks at 19C. The next step is to find out if the high temperature is the cause. So I am planning to install a chiller in the refugium. It will be an Ice Probe thermo electric chiller, which is drop in, or should I say plug in, and has no pumps. It is very weak, 50 Watts cooling, but if it can drag the temp down to 14C the copepods should get a temperature that is in their natural range. I am also curious about what effect it will have on the phytoplankton.

Fun fact: At some point I had a lot of medusae from the hydroids in the DT swimming around in the refugium. A microscope picture of one is included.
 

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Mike_Noren

New member
Norskfisk: Consider trying tidepool species such as Tigriopus brevicornis. It is extremely adaptible to varying temperatures and feeding regimes, reproduces rapidly, and is eagerly consumed by planktivores. It is very small (0.2 mm) but is common here in Sweden so presumably it is easy to get hold of also in Norway. A larger species (T. californicus) is available from aquaculture suppliers.
 

Mike_Noren

New member
Norskfisk: Consider trying tidepool species such as Tigriopus brevicornis. It is extremely adaptible to varying temperatures and feeding regimes, reproduces rapidly, and is eagerly consumed by planktivores. It is very small (0.2 mm) but is common here in Sweden so presumably it is easy to get hold of also in Norway. A larger species (T. californicus) is available from aquaculture suppliers.
 

norskfisk

New member
Norskfisk: Consider trying tidepool species such as Tigriopus brevicornis. It is extremely adaptible to varying temperatures and feeding regimes, reproduces rapidly, and is eagerly consumed by planktivores. It is very small (0.2 mm) but is common here in Sweden so presumably it is easy to get hold of also in Norway. A larger species (T. californicus) is available from aquaculture suppliers.

Thanks for the tip. I actually have blooms of harpactoid copepods from time to time. During the peak of the latest bloom they started swimming actively in the open water too after they had completely scraped clean the walls of macro algae. I did a rough measure of how many that went into the display tank and found that it was about 16000 adults per day. That could amount to about 2 grams wet weight. But this was a rough estimate with very low sample size. But this is an option if I don't succeed with planktonic copepods.
 

AquaticEngineer

New member
If you want any Tigriopus Californicus let me know, I have more than enough growing out in my garage and I know where to harvest them from splash pools along the coast line here. I'm also licensed and permitted to collect and sell fish and inverts I collect.

My next project is going to be adding some kind of surge tank on to my system that I keep all my Tigs and phyto growing out in so that it will dump a large volume of them into the tank, but not all of them at once. Something like a 20 gallon volume that will only dump 5 gallons into the tank when it surges.
 
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norskfisk

New member
For those who are interested: I have started a new plankton project. Zooplankton growth is the goal this time.

Blog here
 

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