i make up my own food mix for my fish and corals, freeze it in old mysis trays, so i had a bleached bta, and was feeding it half a cube of my frozen mix, thought all was great colour coming back accross the nem, then one day i found this floating perfect shaped ball in my sump??? what the hell??? turned out to be the food i had fed the nem the day before. So i agree with the comments that the nems will spit this stuff out during the night.
But, and this is more ticky i read nateps comments about feeding a block of plankton, so this is a larger piece of food made up of lots of smaller bits that Calfo has said is best to feed. Now my food i make up is mush just like a block of plankton would be, its not solid at all and is not that dense, so imo if a nem spat my food blck back out it will spit a block of plankton too....
so after reading all the stuff on the success people have had with silversides and the theory not to feed to larger peices, i now feed my own mix still, but i pick out the chunks of squid or prawn as 5mm roughly and place a few near the mouth. And IMO works best for me.