you don't have to feed BH. i do because it is inexpensive if you DIY and it seems to grow them out nice. flake only doesn't work for me, it all goes over the overflow. i just simply mix BH and Flake, and stick it to the glass. they peck at it there, and when it falls, they slowly finish it. Discus aren't fast eaters. People grow them out on all kinds of things. 20 year ago the experts told me to do it, and it worked then too : )