# [Wet Thumb Forum]-A pea soup tank; good idea?



## Stu (Mar 16, 2005)

Bear with me whilst I explain this out.









I'll soon be ready to start off my first major planted tank and was wondering if I could use it to culture vast numbers of daphnia in it's initial stages. I have another tank containing dwarf frogs and so it would be great to supply them with free food!

The plan would be to run the empty (just substrate and water - no plants/fish) tank for a while with strong lights and possibly CO2, to induce lots of phytoplankton. Then seed it with some daphnia and let them feast and multiply.








Then when I am ready to start aquascaping, I'd turn off the lights (& CO2) and let the daphnia clear up the remaining phytoplankton until the water goes clear - allowing me to start the tank properly.

Would this cause problems with other algae that I would struggle to remove after? Would there be any ill affects on the tank after?

I'd rather not hinder my success in planting if this is the case.


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## Stu (Mar 16, 2005)

Bear with me whilst I explain this out.









I'll soon be ready to start off my first major planted tank and was wondering if I could use it to culture vast numbers of daphnia in it's initial stages. I have another tank containing dwarf frogs and so it would be great to supply them with free food!

The plan would be to run the empty (just substrate and water - no plants/fish) tank for a while with strong lights and possibly CO2, to induce lots of phytoplankton. Then seed it with some daphnia and let them feast and multiply.








Then when I am ready to start aquascaping, I'd turn off the lights (& CO2) and let the daphnia clear up the remaining phytoplankton until the water goes clear - allowing me to start the tank properly.

Would this cause problems with other algae that I would struggle to remove after? Would there be any ill affects on the tank after?

I'd rather not hinder my success in planting if this is the case.


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## imported_russell (Sep 14, 2004)

sounds like an algae paradise, but maybe you could get it to work? if you start getting algae, just shut the lights off for a while.


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## Roger Miller (Jun 19, 2004)

Light and CO2 in an unplanted tank won't automatically get you green water. Of all the algae problems I have had in new tanks, green water hasn't been a common one.

CO2 may do little or nothing to help grow phytoplankton. They seem to do very well without it. Anything you want to grow will need nutrients. A little added ammonium may be needed to get things growing. You can go through all that and grow periphyton instead of phytoplankton. If that happens then you will be left with a messy-looking new tank that won't grow any daphnia.

Um, otherwise it seems like a fun idea.


Roger Miller


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## Stu (Mar 16, 2005)

> quote:
> 
> Originally posted by Roger Miller:
> CO2 may do little or nothing to help grow phytoplankton. They seem to do very well without it.


Phytoplanktonic organisms photosynthesise much in the same way that aquatic plants do, thus needing the same nutrients and requirements, albeit maybe in different quantities.

I found this information...


> quote:
> 
> Phytoplankton remove almost as much carbon dioxide from the air as land plants
> 
> For every 106 atoms of carbon they make into organic matter, they need 16 atoms of nitrogen and 1 atom of phosphorous. Most can't use atmospheric nitrogen gas (N2) directly but need chemically reactive forms of nitrogen such as nitrate (NO3-) or ammonium (NH4+). There is always plenty of carbon dioxide so phytoplankton keep growing until they have used up all of the useable nitrogen or all of the phosphorous, which ever runs out first.


Phytoplankton populate the surface of water bodies naturally because that is where the sun's warmth has heated the water, where CO2 can be utilised from the atmosphere and where nutrients reside that have been brought up in the convection currents.

Therefore, surely if I provide CO2 throughout the water, heat, dose high levels of NH4 and PO4 and illuminate all the water (easily possible with my power compacts), then this will create hopefully near ideal conditions for growth?

I would use a litre culture of freshwater Nannochloropsis to kick start it.


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> ...if I provide CO2 throughout the water, heat, dose high levels of NH4 and PO4 and illuminate all the water (easily possible with my power compacts), then this will create hopefully near ideal conditions for growth?
> 
> I would use a litre culture of freshwater Nannochloropsis to kick start it.


Sounds like a plan that should work. I think it would work with or without the added CO2 as algae seem to be very adept at getting their carbon requirement without it. If the culture gives an immediate green water bloom then that may suppress the usual succession of periphyton.

Roger Miller


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## Ben C (Apr 16, 2006)

could you try it smaller scale to start with? in theory it sounds fine.. but...... !!


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## Stu (Mar 16, 2005)

Lots of people have cultured phytoplankton in small soda bottles and the like for the purpose of feeding fry and raising small aquatic organisms. These seem to work well with no ill effects. You can even buy expensive reactors that culture some for marine use.

The only thing I am currently a little concerned about is the current, or perhaps lack of it!
In these small systems that people make, they usually keep the water moving by the use of air pumps.
I'm not sure whether the filter will move the water fast enough.


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## noah_greenberg (Aug 20, 2004)

Hi Stu,

While I may be an amateur planted tank hobyist, I was once proffessional phytoplankton and daphnia culturist. I worked in a research lab where we were studying Daphnia pulex and I managed the zooplankton and phytoplankton cultures. I think your plan is a good one. I would caution you that I agree with Roger that clearing the pea soup isnt always easy. On my first set up I had to purchase a UV filter before I could really beat it! I have also known some people who cultured aglae in fish tanks and the algae was often contaminated by bacteria which would harm the Daphnia cultures.

Here is another option: Since Daphnia are a great live food for your tank inhabitants and the pea soup is tough to get rid of, have you considered making up a culture bottle that will provide you with algae and let you maintain your precious tank at optimal conditions? This will be quite easy:

THE CULTURE TANK:
-Obtain a 5 gallon glass carboy (or smaller if you dont need too much algae). This will run ~$20.
-Get an apropriately sized rubber bung for the top and drill 2 holes into it.
-Run glass or rigid plastic tubing through one hole to the bottom of the tank.
-Place a two inch piece of tubing through the other hole for a vent.
-If you run air through the long tube you will have a constant source of water movement and your algae will be suspended. CO2 in not necessary for great algae growth.
-Place carboy in south facing window and you should have good growth. Additional lighting is good if you want to speed things up.
THE MEDIA:
You can use the same fertilizers for your algae as you would for your plants. Alternatively, you could use a more refined recipie like the ones used in laboratories or fish hatcheries. Aquatic Ecosystems (www.aquaticeco.com) sells conc. algae media that will work great.

THE ALGAE:
Daphnia are fairly pick eaters. If you want to get big ones, I would suggest Chlamydomonas reinhardtii, Scenedesmus obliquus or Cryptomonas erosa. These can be bought from Carolina biological supply amongst others. Other algae may work fine, but I had some frustrating months where I was feeding sub-optimal food and my Daphnia cultures suffered.

NOTES:

Pull of 1 liter at a time of your mature culture and replace with new media. Aglae can be stored in the fridge for up to 1 month. After that it gets funky and is not suitable for Daphnia.

I would try to keep things clean. Every month or so it would be a good idea to sterilize your culture container and start fresh with a small sample of algae from your last harvest.
Brewing stores sell no rinse sterilizer which is great for this.

DAPHNIA:

Daphnia do not seem to do very well in most of my tanks. They are a little tempermental and need conditions to be optimal if you want them to reproduce efficiently. I would use 1 gallon jugs to grow them out, placing 30 adults in a jug and feeding it daily for 1-2 weeks. After this time, you should be able to harvest all but 15 adults and start again. A fine mesh screen works well to strain them. Think about ordering Daphnia magna. They are the biggest and easiest Daphnia to culture. Your fish will love them!

If you do this and get your system down, you will have Daphnia for your tank inhabitants and enough to sell to your LFS. Let me know if you want more info on any aspect of this system or others.

Good luck!


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## Stu (Mar 16, 2005)

Thanks for the detailed info Noah!









That seems a much better and easier way of culturing daphnia with the added bonus of always having a supply on the go.

Now to see if I can find a carboy around here.









I'm sure I'll have many questions when I first get it set up!


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## Stu (Mar 16, 2005)

First question!









It occured to me that you never mention the temperature throughout your method. Is this critical at any stage? will the algae or the daphnia be harmed by swings in temperature?


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## noah_greenberg (Aug 20, 2004)

In my experience, temperate Daphnia and do best around 70F although they will survive at a wide range of temperatures. The reproduction rate of the Daph will drop off if you stray too far from this temp., and if you go to extremes they will produce resting eggs and die. Algae can be cultured at slightly higher temps and should have high growth up to 78F. You should check with whoever supplies your initial cultures. Alternatively, you could go collect your own zooplankton from a local pond. Phytoplankton may be worth buying.


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