I'm n skimmer DIY'er. I have not yet tried to work much with acrylic and such. However, first thing tat stands out to me, is, shouldn't your venturi be on your recirc pump INTAKE rather than output? This way the impeller is what is "chopping" up the bubbles? Also, the water input I would not use my overflow. I would have it coming in to the skimmer and leaving from the bottom and I would use a seperate small powerhead to feed the skimmer from the sump. LOL, I just noticed this thread is 4 pages long. I'm sure everything I just said was addressed several time. Oops.