WHY DOES THE SAND COME BACK IN THE POOL?
If it only happens after a backwash and in small quantities, you probably skipped a step when you did the backwash. Set the filter on "WHIRLPOOL" or "RECIRCULATE" for 30 minutes, then back to filter.
When you backwash, you should always do these 4 steps :
- Backwash 1 - 2 minutes
- Rinse - 30 sec - 1 min
- Whirlpool or Recirculate 15 min
If, however it is continuously and more than about a handful of sand, you need to check the filer. The lateral assembly inside is probably cracked or damaged.
Stop the pump, drain the filter, remove the head and remove the sand, using a shop vac or small ladle.
Once it's empty, lift the lateral assembly so you can reach and remove the laterals, turning counter clockwise about a quarter turn. (If your filter is a more recent Hayward model, the lateral fold upwards like an umbrella). Take it out and examine it.
If a new lateral assembly is required, take all the broken parts with you, as the total length is needed to get the right model.
The lateral assembly is placed back in the middle with the laterals. Place a glass upside-down over the top of the assembly to ensure that no sand goes into it.
Fill the filter tank with sand up to its shoulders.
Put the filter head back, making sure that the lateral assembly end and the one from the head fit into each other.
Put the handle on backwash for about 1 minute to make sure that the dust will not be coming back into the pool, once you restart the pump.