My tank had been up for almost a year without a skimmer with no problems. I had a little extra money come in and decided why not try one. I bought a Coralife Super Skimmer and it works great. The issue is now that the dark green/brown gunk that the skimmer pulls out smells like ... I can't describe it but it is bad. They should make people drink it on Fear Factor. Anyway does anyone use any type of stick on air freshener under their stand? Would it be harmful? The smell is not that bad until I go to dump the skimmer cup but I do get a whiff everytime I open the stand doors.