Right you are, Don. (Although I didn't know that they can only pull -3PSIG. I was guessing about the water pull, since I've had to use mine a few times to clean up a flooded basement. (And no, I didn't flood it for indoor roll practice!)

I used the Shop Vac's superior flow rate (mucho CFM) to start my bagging and suck out 99% of the air. I then slipped in the vacuum pump hose to really suck things down tight.

Shawn

: Shop vacs max pressure is rated in inches of water. A vacuum pump is measured
: in PSIG. Most good shop vacs can pull 70 - 100" of water, or about 3
: PSI (negative). That's a huge difference from a vacuum pump at -25 PSI. Of
: course, the vacuum pump can only pull a few CFM...