Sand filters capture particles down to 20-40 microns.
A slightly dirty sand filter works better at capturing and filtering stuff. Only backwash when your filter pressure raises 25% over your baseline clean pressure.
Adding a small amount of DE can improve sand filter filtering.
How to Deep Clean a Sand Filter?
Deep Cleaning a Sand Filter has instructions with pics of the deep cleaning process.
My sand is "channeled" how to fix it?
- Open up the filter so the sand bed is exposed.
- Stick a garden hose into the sand and turn on the water. The sand should loosen up and all the dirt and gunk should float and overflow out of the filter.
- You might need to stir up the sand a bit. Keep this up until the water overflowing out of the filter is clean.
- If any sand is clumped together CAREFULLY break it up with something like a broom handle but BE VERY CAREFUL NOT TO DAMAGE THE LATERALS. You will be surprised at how much stuff this gets out of your filter than backwashing doesn't and I feel this 'deep cleaning' should be done yearly.
- This should take care of the channeling but if the sand has a lot of calcium deposits you might want to follow this up with an acidic sand filter cleaner from the pool store.
- GENTLY tap on the sand tank with a rubber mallot and watch the pressure gauge climb about 2 psi.