Ben , correct me here if I'm wrong, or just delete my post. I had a discussion with a Pentair rep about adding some DE to the cartridge filter. He said that cartridge filters filter better when a little bit dirty. So they recommend on start up to add a little DE to jump start this process. Since my current cartridges are a couple of years old, I no longer do this because I never really get them that clean. If you do add DE just add a little through your skimmer line, maybe a half a cup.

On another note, I must say that my 2 speed Whisperflo pump is great. When on low speed, which is almost all the time after initial cleanup, it is 1/4 horsepower. Enough for a good flow through the 6 returns but not enough to get water up to the slide, for that I run it on high, which turns it into a 1 1/2 horsepower pump. This is plenty for my pool. It's a simple pump with no fancy electronics to burn out.

Tom