How long should the pool filter run?

Depend on your geographical location. Here in FL, and most warm southern states, 8 hours in the winter and 12 hours in the summer if you have standard 1.5" Plumbing. With 2" plumbing, and an extra large filter (60 sq ft D.E or 400 sq ft cartridge), you can reduce that by half. In northern states, the times will be less.

---- We run ours here in California for six to eight hours a day, depending on the season and our level of use. Here's a troubleshooting guide for Hayward pumps that applies to most pumps in general:

http://shop.bluehaven.com/product/6701/hayward-information