I've posted on here before about not getting enough bubbles in the skimmer. (css 220) I have cleaned it all out, raised the pump closer to the surface, made the air intake hole a little bigger, and still not enough bubbles. I don't get any foam at all, I have to keep it adjusted so that what bubbles are in there are at the top of the collection cup..Could it be a bad pump? Like I said its working, just not like it is supposed to. Also, on the bubble diffuser it is about 1 inch above the white pad, and the diffuser itself is about 1/2 above the water. No hoses or airlines are clogged, it's basically as clean as when I got it out of the box...Are there any adjustments i'm missing, or should I just try and replace the pump..i know it's a rio, but I don't know what size...Or can I just run an airstone to the bottom of the unit to help with the bubbles???