An update I bought one of the early models 220 with the Sicce pump and I upgraded to the Tunze 9420 about 4 months ago. After I took it out and cleaned it I put the pump back in and noticed that the air line tube was twisted the skimmer seemed to be working correctly but I noticed in the past of a very slow skimmate production like a finger wide in three or four days, since I have a nitrate problem red slime problem and hair algae problem I was perplexed . So I made sure that the air line tube was not twisted, this is the part that goes from the skimmer to the air tube it is about 1 1/2 long my skimmer is now pulling two cups a day out on my 120. So my recommendation for the Tunze owners is check the air tubing for kinks or twisting and also check the electrical cord for splitting where it enters the pump there is a 2 year warranty on these pumps. PS for the 400 users there will be a bigger Hydrofaomer than the the 9420 more like a Askol 1500 I believe.