I have had the v2 skimmer in my biocube 32 for about 2 months now. I have had since I started the tank. Adjusting the air flow in your skimmer so the bubble are reaching close to rim is very important, and your water level. After running it for 2 months it pulls a dark green foamy liquid. So much foam that I have to tape the lid closed so the foam don’t push the lid open. For 50 dollars and from just visually seeing and smelling what the skimmer pulls out I would have to give it 5 stars for a nano skimmer. It took me awhile of tuning my water level and adjusting the air flow. Which is probably why everyone says it don’t work..