My filter pressure rises after backwash?

Always keep a nice clean, balanced pool to avoid this from happening.  The filter might be clogged up with dirt, or minerals, which causes the pressure to rise.  Try to maintain clean grids by cleaning them out as much as possible (at least one time per season, we recommend a couple times).  It may require an acid bath or just a grease clean.  This will get everything cleaned up nicely allowing for a nice area to filter again.