I have been cursing my new skimmer since I bought it about 4 weeks ago. It would almost never foam and I could not understand why. All parts of the skimmer were working properly, the pump was running well and there were billions of tiny bubbles in the mixing chamber but no foam was produced (or very little). I recently upgraded a very undersized return pump that was used for the sump that housed the skimmer. Bingo. I probably at least doubled if not more the amount of water running from my tank and back to my tank. The skimmer went nuts almost instantly. I played with everything I could think of and no solution could be found. Amazing that I had not even considered the waterflow to the sump. Although this seems like a no brainer, it is just another example of how we sometimes can not see the solution for looking too long at the problem. I have recently seen posts on this BB concerning skimmers not skimming and just thought I would pass on my recent experience.