My SC150 on my 55g pulls a cup every two days, tried the mods out, I find I can make the think skim much better without any mods to it. There are extrrmely touchy as far as the air intake settings are concerned. I do agree with everyone, it's an inferior skimmer, but I have had my 55g for going on two years now, very little problems if ever and none have been because of my skimmer. If you have an extremely tight budget they are definatly better than nothing. And I do plan on buying a SC100 for my 29g. it'll work good enough. Now for my 220g, you couldn't pay me enough to run a sea clone on it. In fact, the 55g is probably the largest tank I would attempt a SeaClone 150 model on. Even though they're rated for 150g (yeah right!).