Hi Spider;

What Waterbear was probably referring to are manufacturer statements to the effect that soaking DE filter membranes in acid BEFORE you degrease them can result in permanently bonding the grease (or acid-grease products) to the membranes.

I have told people this myself, but I have never actually verified whether it was true or not.

I would encourage to make sure your pool is completely clean and algae free before you close. If necessary, cover it and then filter and chlorinate till it's spotless . . . before you winterize it.

If you have to raise the chlorine quite high, make sure you leave the pool partly uncovered to the gaseous chlorinated byproducts that form as chlorine destroys 'goo' can exit the pool.

"PoolDoc"