Forgive me if I misunderstood your question. Are you planning to breed micro-food in the tank to supplement fry/adult fish's diet?
If so, my suggestion as follows.
Daphnia require stable food supply to multiply. The food of choice is green water. Being the same tank, when you are feeding daphnia, you risk polluting the whole tank. It is best to breed daphnia in a separate container due to the high nutrient level of the culture water.
On the other hand, there are other food you could choose to provide constant micro-food, live food. Newly hatched brine shrimp.
There is one hatcher to be used in FW tanks for continuous hatching of brine shrimp.
This is an inexpensive hatcher for brine shrimp. The chamber to the left is filled with saltwater, and the chamber to the right connects to the tank and will be filled with freshwater. Where the 2 chambers met water will not mix due to the specific gravity of saltwater is heavier, will keep to itself in the salt chamber.
Brineshrimp cyst tossed to the top of the SW chamber, after 12 hours artemia hatched and will naturally swim toward the light at the exit. This way your tank is provided with continuous live food.
Another possibility is decapsulated brine shrimp cyst. These are the same brineshrimp eggs that you buy at the LFS, except the indigestible hard shell has been chemically removed (melted). The embryo inside the egg is still viable, just the shell is removed.
The decapsulation process was done with chlorine which melts the outer shell, and at a precise time the brine shrimp egg is rinsed, de-chlorined, and dehydrated, setting brineshrimps egg back to dormant stage.
The decapsulated eggs can be fed just as it, or put it in SW to hatch, and the size is perfect for all fries.
The decapsulated eggs can be purchased through brine shrimp farms such as www.brineshrimpdirect.com