I have an older style one on a 120 with a 30 sump. They are hard to adjust until you get the hang of it. A properly sized pressure rated pump is key. I tried a mag 12, mag 36, ampmaster 3000, iwaki 40rlt all were mediocre at best. I now run a throttled panworld 200ps on it and it skims very well. The injection system is not sealed so you are limited on how hard you can overdrive them before water flies out the bio towers. Overall I think its a good solid piece of equipment. Way overpriced at 660.00 though, considering you need a 250.00 pump to run it properly.