Quote Originally Posted by Poconos
From what you describe I assume you have an in-ground pool with the filter and pump above the pool waterline. If this is the case then nothing will prevent water from flowing back to the pool through the skimmer and return lines when you open the system to air. There is not normally a check valve in the skimmer line. Some situations...maybe. I don't have a DE filter so I ask, why do you want to drain the filter? If it's to work on it then I don't know how to prevent DE from backing through the skimmer. Hopefully someone with experience with DE filters will kick in. Not much help here.
Al
yup, IG, and the only reason to drain was to inspect the grids or clean the filter. not really concerned with it going back through the return (there should be de on that side). i guess i could add in a ball between the pump and filter, but this is another, more solvable issue. mostly i'm concerned with the pressure/de problem.