I also use green seaweed. if your grocery store doesnt carry it, then try an asian market store. it literaly is the same stuff that is used to make sushi, i reccomend getting the large sheets, and not the small single individualy wrapped pieces, those generally have preservatives added to them. also, on your clip, i reccomend taking your piece of seaweed, maybe a 4 by 4 inch square, and then folding it in half twice. another words, instead of having one big piece on the clip, take that same piece and fold it in half, then fold that in half, then put that on the clip. this helps from the large piece getting tugged off and then floating and cloggin up your powerhead or drain. I have a powder blue and a yellow tang and they love it. my gobies for some reason also eat it.