Swimming Pool Sand Filter..Pool Seems To Be Manufacturing Small Debris

by John M
(North Stonington, CT)

Question About Dirt Going Back Into The Pool...

To fix the problem, I replaced the 20 year old Hatward filter with a new Hayward filter. I put in new silica sand and backwashed it until clear. I re-used the hoses and pump, which are only a year old. I also bought a Pool Rover, which seems to pick up the debris very well.

This morning, I vacuumed the pool and got it very clean. When I backwashed the filter, I discharged it through a 2 micron filter bag. Results were as expected - the bag contained everything that had been trapped by the sand filter.

I cleaned the filter bag and held it in position so the pump dicharge in the filter mode was being filtered by the same bag. 5 minutes later, inspected the filter bag and it had not collected anything.

An hour later (still running the pool pump and filtering with the sand filter, checked the pool and saw debris beginning to collect in the small wrinkles in the bottom.

I am at my wit's end trying to figure out where this debris could be coming from (or where it is hiding)!

Please give me your opinion.

Thanks for the question John

I would advise you to check if you put the correct size pool filter media sand in the sand filter.
Be sure you didn't brake any laterals as a broken lateral will cause sand to go back into the pool.

Also be sure to check the amount of swimming pool sand. Too little or too much will affect filtration. Many instruction manuals should have a measurement in inches from the top of the sand to the top of the filter. I keep the Y's Hot Tub sand filter at 10" and both pool filters at 13" for maximum filtration.

New pool sand will have some dirt on it so a little sand and dirt going back into the pool is normal and will decrease as the sand gets used and settles in the sand filter.

Next, it sounds like you might be backwashing a little too much. A swimming pool sand filter needs a little bit of pressure, but not too much, to work. You normally want to backwash when the filter pressure gets between 8 - 10psi over "just backwashed" pressure.

Be sure to RINSE after you backwash. There's sand and debris that gets caught in the pipes during the backwash. When you start the pump motor up again that pool sand and debris gets put back into the swimming pool through the returns.

Good luck and let me know how this works for you

Robert