Don't hold me on this but think u get something like turkey Baster put food in and point it towards fish but sure if u googled it will tell u more. Yeah I don't touch the back so there's always algae, what I mean is bad algae like hair algae just one of kinds can get. Over feeding can have big part to play if u have bad algae growing so that's one way you could find out but really think feeding down to the person as everywhere says different so as long your waters good then will be ok