I am loving my APF-600. I started many years ago with the Saunders Skimmers with wooden air stones, then made my own, bought some made by a friend. Got out of Salt for about 5 years, came back to the Prizum, then Precision Marine HOT-1. Finally got a Euro-Reef CS5-2. Thought the pinwheel was great till the water in the venturi wasn't lasting more then a day or two, but it was skimming better the anything I'd had till then. Well got rid of my old 110 and bought a new one, read up on all the new gizmo's. The one thing that never changed was the Deltec Skimmers, Euro-Reef had to shut down its Forum here again because of dissatisfied customers, but the overpriced Deltec owners always bragged about their "Nog" I kept asking around, wanted to see one in action but at $8XX something no one was going to keep too many on the shelf. I finally said the heck with it one night about 8:00PM, called Doug to ask some questions and decided to get it then before I chickened out. I was not disappointed. It started producing foam from the first minute. I have two Clowns and a few small rocks from my other tank in new SW in an unlit tank and have cleaned the cup 3 times already. The cool thing is putting your finger over the air intake, it really sucks it in and tries to hold. I feel it is well built, smart built, the pump run way cooler then my Euro-Reef. Some say ER's are better built because they use better/thicker acrylic, but I like the way Deltec mounts the return better and I think the fittings look cleaner then the UniSeals ER uses. But most important, results, results, results, it is cool being able to play with the air valve and get a thick foam , tiny bubbles the way I want them. I know some ER folk will point out comparing the CS5-2 to the APF-600 is like comparing apples and oranges and I agree, the sedra pump is no comparison to the Aqua-Bee 2000/1, one is a recirc the other is not, but the engineering thought between the two is evident.