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Daphnia as Absorbers

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Will adding daphnia improve water quality? When they reproduce, the added mass of the colony has to come from somewhere- I'm wondering if they filter your water to some degree?

I'm not thinking of adding greenwater or any food to the tank though- it's my shrimp tank. But I thought I might grow daphnia for the purpose of further stabilizing my ecosystem. And to raise food for other fish.

Would daphnia die off if you don't feed them? Or will they survive on algae and stuff in the water? I have a 55 gallon planted tank, btw.


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It is possible to raise daphnia in a shrimp tank. They can eat more than just green algae water, they can eat yeast, egg yolk (hardboiled dry/crushed powdered), blended green peas, and more. The algae water is convenient since it "filters" the water (uses up ammonia, nitrites, nitrates), making it cleaner/healthier and is a constant food source that isn't polluting like lingering food would. I think golden pearls (smallest micron sizes), finely crushed up flake food might work. Anything small really, but daphnia cultures aren't all that stable, so clean, healthy water and feeding often is needed or else the culture might crash/die.

I haven't tried the yeast feeding, sounds like a nice method, but I am unsure how it affects the water quality.
By the way, I think daphnia like cooler temps (68-70*F).

But, what do you mean daphnia as absorbers/improving water quality? They won't really make water quality better, they are just another livestock that also adds bioload to a tank (all though not much). And by them eating the green algae water, they are actually removing the algae that is making the water healthier.
 

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You need to use a combo of yeast and flour I believe, and tiny amounts to avoid fouling the water. I kept a colony going for almost a year, then one day it crashed hard.
Green water is far superior and easier, a simple collection of mason jars with tank water after a water change in a sun lit window sil or on a patio grows green water quickly

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I agree on the greenwater feeding. More nutritious that way IMHO. Additionally, the greenwater while in suspension will absorb the nutrients that OP is considering adding the daphnia for. @MassiveDynamic17, the idea would probably work...in a much larger tank. Reef tanks still have pelagic copepod species in them, which have to subside off of something. Under that logic, a small daphnia population should be able to live in the tank, but would probably grow better with the addition of at least a little bit of greenwater. Adding said greenwater would also help with some nutrient issues since the greenwater absorbs nutrients, and the daphnia eat the greenwater, and you take out the daphnia.

Flakes: No. You'd have to get the flakes into the micron size, which I'm pretty sure is nearly improbable with most home techniques (even if you crush them up really really small). Additionally, those flakes will contribute to nutrients within the tank.

Yeast: Yes, but sparingly, and no flour. From what I've read, adding any dead food, like egg yolk, dead greenwater, powdered ham and pea soup, yeast, and dung(used to boost floating bacteria levels that the daphnia eat), requires a bit more care since if you overfeed, you risk killing the daphnia off due to excessive spoilage of food. Just enough to make the water slightly cloudy is good.

Temp: Daphnia can live in warm ponds, and produce ephippia once they start getting in bad conditions (overly hot (>80) or very cold (no idea), large amounts of phosphorusin the water, etc.).

Filtration: Small, air powered sponge filters work. Not the ones that vigorously aerate the water, but normal ones that barely move the water around work. As does just a small amount of aeration as well. This way, not a lot of the daphnia get trapped and die.
 

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Feed just enough so that the water will clear in a couple hours.

I highly recommend Daphnia and other freshwater plankton over brine shrimp, for freshwater tanks. The Freshwater cousin of Brine shrimp are Fairy shrimp and are hatched and raised the same way.

You can have a lot of fun raising live foods. You'll be in control of your fishes health.

Choose a live food that will not be too big for your fish.

Daphnia magna are too large for many fish we keep. Daphnia pulex may be just right. Moina may be too small. You could use a net to only cull the right size Dahnia.

Daphnia filter feed from the water column. Recipes can be simply green water made from aquarium water, or purchased alga such as Chlorella (fresh or marine), or liquid foods like coral food or homemade recipes of inactivated yeast, blood meal, soy flour, manure, all the way to sewage sludge. Yes, these guys have been used to clear up grey water.

Where do you get them? Ditches, fountains, and small pools, Online. Obtain a small batch because they will adapt to the environment.

Do use a simple acrylic airline tube without an airstone to gently aerate the water.

Airstones will produce fine bubbles that will get trapped in the carapace and suffocate the little guys.

Light will keep the algae growing and you will need a lot of green water. So plan to make a supplemental liquid food.
 
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