Sand blowing back into the pool after backwash

[John Faulkner]

Every time I backwash and restart, a bunch of sand shoots into the pool through the returns. Happens only for a few seconds but it’s annoying. Any ideas?

 

[Silvestor]

Happened to me too turned out my multiport valve gasket was worn and leaking sand past. Replaced it and problem stopped.

 

[syedsam]

Sounds like a cracked lateral inside the filter. Once it breaks, sand sneaks through.

 

[Manikshaw]

Could also be too much sand or the wrong grade. Double-check what you put in last refill

 

[Kevin Marsh]

I’ve run into that same issue before and in my case it wasn’t a broken part, it was just the way I was restarting the filter. After a backwash the sand bed inside the filter gets really stirred up, and if you switch the valve straight back to “filter” mode, the loose particles have nowhere to go but back into the pool. That’s why most manufacturers recommend running the “rinse” setting for about 20–30 seconds after every backwash. It settles the sand bed again and flushes the loose fines out through the waste line instead of through your returns.

Another small thing that can make a difference is how fast you start the pump back up. If the system kicks on at full force right away, it can disturb the sand bed more than necessary. I got into the habit of bleeding air from the filter first and then letting the pump prime smoothly, and that cut down the problem a lot. If you’re already doing both those things and still seeing sand, then I’d lean toward one of the mechanical issues the others mentioned like a lateral, gasket, or even sand grade.

 

[Lily Allen]

I had the same issue too, it turned out I wasn't giving enough time for the rinse cycle after backwashing. When I switched the valve back to ‘filter,’ the loose sand had nowhere to go but back into the pool. I now run the rinse cycle for about 20-30 seconds after every backwash and it works great. Anyone else run a rinse cycle after backwashing?

 

[Henry Thompson]

When I had sand blowing back, I discovered that my filter was only slightly overfilled from the last sand change. It didn’t seem like a big deal at first, but even that extra couple of inches gave the sand less room to settle after a backwash.

Once I scooped some out, the problem stopped. If you’ve checked the valve and laterals already, it might be worth taking a peek at the sand level just to rule that out.