Samson wrote:
...
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?

Most of the DE is disposed of with the backwash. Running the filter
without DE can prematurely clog and damage the filter grids. Disposing
of DE prematurely is both economically and environmentally inefficient.
Better solutions include adding a drain valve to the filter system
somewhere past the pump output, using a portable sump pump, or using a
siphon hose if there is a location within reach that is lower than the
preferred water level.