We have a small pool in our home owner's association. We have a pool
maintenance person who I trust to keep the pool safe enough to pass
yearly health department checks but I don't trust him to know this:

During the winter we turn off the heat and cut the pump/DE filter
time down to four hours a day. A couple inches of rain requires that
we back flush the pool so that it doesn't overflow into the adjoining
spa that we are heating.

My question is should I be adding DE every time I back flush the pool?
During a wet winter I might be back flushing 10 times. Does it hurt
the filter grids inside the filter if they do not have DE on them
while the pump is pushing water through them?

\Samson