I think alot of skimmer is very good......not just H&S (what everyone is talking about)......I'm not say that H&S is not good.......the fact is H&S is a very good skimmer.....but not everybody can pay thousands and thousands of dollar to buy it...... now is about the question how big should I buy.... ocz the bigger the better...but if you have 125gal you should look for a skimmer than can handle 200gal.... if 50gal look for skimmer can handle 75gal and so on.... Here is some good brand name in Canada and US and most ppl use and the price is more reasonable...... Euro Reef ASM ( same as the euro reef but use diff acrylic ) but cheaper price... AquaC Precision Marine D&D ETSS MARINE TECHNICAL CONCEPTS HSA all those are very good skimmer........good luck....