I didn't purchase mine from this seller but still feel I need to leave my opinion on the product. If your tank is large (75-120 gallons) and very lightly stocked then this would be a good skimmer. Otherwise, it's very sensitive to chemicals (why I recommend with a large water volume) and very difficult to tune (which is why I recommend for a lightly stocked tank). On my system (40 gallon breeder with sump SPS dominated tank) it spends half it's time turned off. I can't raise it higher in the water otherwise it leaks bubbles so I have to keep it in 8" depth water. At that depth it can go from good skimming to bubbling over within seconds of one tank change or another, such as feeding time. I'll be replacing mine soon with something that has better seals and a DC motor for better control & bubble management.