I cultured daphnia indoors for awhile using yeast and spirulina powder. It was a little more work than I wanted to invest.
I put the 5 gallon bucket of daphnia outside and it has thrived for 3-4 years with no care from me. They feed on algae that grows inside along with plant debris that fall in. I live in the Midwest of the USA, so I don't get to use them in the winter when the bucket freezes, but they are plentiful come spring and summer. I don't know how they survive the bucket freezing. I live in Minnesota, which can get as cold as the arctic on occasion!
I would highly recommend starting an outdoor culture if you have the space (don't need much), and can set out a bucket without causing any safety risks to children and pets.
Good luck.