raising copepods

I've been keeping thread with my experiments - on good days (when I keep salinity consistent despite evaporation), each tiny tank culture pulls out the equivalent of bottle of pods - since each bottle goes for about $22-$30 in DFW metroplex, that is a $90 savings... not that I have that kind of money to spend every day on my fish. Instead, I have the three (to five) pod cultures so I can pull out about bottle of pods a day without spending much (seems less than $20 year for spirulina powder). Fish are fat, so I'm happy