: So, the strum box slowed the pump rate by about 20%. But perhaps the more
: interesting comparison is 3 to 4 gal/min compared to the advertised 10
: gal/min.

Thanks for the research that I've been too lazy to do. I installed a 500 in my Return, and like the concept but won't do it again. My hand pump from NRS pumps at least TWICE as much water with less effort than the 500 with a light spring (and no strum box).

jrs