i put a batch in my tank but i never see them. just be sure that if you do put them in the tank that you turn the lights off first. i learned that the hard way. the fish wont see you putting them in with the lights off and wont come over and eat them all.
btw, i just re=read their website, and it seems they are not good for cultures for use with live phytoplankton. sorta stupid, but it seems they are just detritus eaters, not algae eaters.