For a while I was not separating the BBS from the shells, I was just filtering out all through a brine shrimp net and feeding the mix. But if you look closely at the picture, one of the bottles has a valve on it like you get on refillable water bottles. You pull out the aeration tube and let the hatching solution set a couple minutes. Then drain through the valve until there is no red color in the otherwise colorless stream, collecting the BBS in a brine shrimp net. I just pour back the recovered liquid, add more eggs and repeat hatch and harvest about two weeks before changing the water to fresh salt water.