Totally agreed, I'm in a photography class right now. Can't say I've been a photo-buff since I was eight, but I'm definately having more fun with it recently. Maybe I'll get some scans of my prints up if we ever make any (B&W film SLR work) Agreed on the pressure thing. I just don't see how the decerase in pressure (by boring-out the intake hole) would change the calibration. It WOULD definately change the flow, but it seems to me that 1RPM in the meter would still equal x l/m. Must be changing how the water actually hits the impeller, rather than the actual pressure. You're right, as long as it's not zero, it's fine http://www.thinkgeek.com/tshirts/science/60f5/ Just for the record.