Soooo, I've just finished up a SLAM from an algae outbreak - whew, that was a lot of work . I completely understand HOW to backwash and now I understand HOW to RINSE. I guess I'm still confused on WHEN to backwash. We have a sand filter, live in a wooded area, and have a dog that is in and out of the pool all day - gets wet, goes rolls around in the dirt, gets back in the pool. I've read that you backwash when your PSI raises by 10 and I've read that you go by 20-25%. Was there a difference in my backwashing during a SLAM, than routine backwashing? My gauge for normal PSI is at a 10. So I guess my question is do I backwash when my guage reads 20 or when my guage reads 12? Is it too frequent to need to backwash more than once a week?