I have only had my fuge set up for a few months and it was working great until recently. I am noticing a sulfur smell coming from the fuge. It is a 20g with 5" of sugar size sand and a ball of cheato floating around. The fuge does have lots of slimy algae in it which I think is from the light that the cheato grows so well with. I also hang my protein skimmer on the fuge. I read that it is probably sulfides but I have read conflicting ways of treating the problem. Is the flow supposed to be slow or fast? Should I add sand sifting critters or do I leave it alone?