Taking care of BBS is a lot of work. I normally just feed the BBS to my fish once the BBS hatches so I don't have to worry about water changing it, shocking it or feeding it.
I take a small mason jar, add three teaspoons of salt, 1/2 tsp of eggs (feeding 7 tanks) and an aerator. I stick a piece of rigid tubing on the end of the airline in the jar so it's easier to siphon out the BBS.
I set it ontop of an aquarium lamp (hatch better in warmer water) around 9-10 at night and the next day around 9 the BBS is mostly hatched. After about 24 hours (they can go longer as well as hatch sooner) unplug the tubing and let the jar settle. Hatched eggs float to the top and unhatched eggs sink to the bottom. On top of the unhatched eggs will be tiny red BBS. Some will also be swimming. I hear the kind that isn't free swimming yet is much healthier, but I just siphon it all out leaving behind the unhatched eggs and egg shells. Then I dump the rest of the stuff from the jar in the sink, rinse it then start over. Rinse off the BBS in a fine mesh net too to remove the salt water.
It is much easier than it sounds. And it is pretty hard to mess up. Just make sure you have almost enough aeration to bubble water out of the jar, the more the better.