BBS lose all their nutritional value after a day.
I always used a jug, some salt and an airstone, The warmer the water the faster they hatch. When ready to harvest, turn off the air and cover the top so its dark under the cover and wait a few minutes. The bbs go to the bottom and the egg shells float. Use a turkey baster to remove the BBS.
I use a piece of a coffee filter and put the bbs into it, rinse it to get the salt off and then put them into a small container of water. Rinse the baster and use it to suck up the BBS and squirt em into the tank.
Viola - E Z and cheap.