Sand blowing back into pool after backwash.

[Freddie]

I’ve got a sand filter and lately, after I do a backwash and then switch it back to “filter,” I notice fine sand collecting on the bottom of my pool within a few hours. I replaced the sand about 3 years ago, so it’s not that old. Do I need to open the filter and check laterals, or is there something else that could cause this?

 

[Isabella]

I’ve got a sand filter and lately, after I do a backwash and then switch it back to “filter,” I notice fine sand collecting on the bottom of my pool within a few hours. I replaced the sand about 3 years ago, so it’s not that old. Do I need to open the filter and check laterals, or is there something else that could cause this?

That usually points to a cracked lateral at the bottom of the filter. Even one small break can send sand right back into your pool. I had to take mine apart last summer to replace two of them.
it’s a bit messy but not too hard.

 

[Zephyr]

I’ve got a sand filter and lately, after I do a backwash and then switch it back to “filter,” I notice fine sand collecting on the bottom of my pool within a few hours. I replaced the sand about 3 years ago, so it’s not that old. Do I need to open the filter and check laterals, or is there something else that could cause this?

It could also be that the multiport valve gasket isn’t sealing properly. If water bypasses where it shouldn’t, it can pull sand along with it. Before tearing the filter apart, maybe check that first it’s a cheaper fix if that’s the issue.

 

[Lily Allen]

I had a similar issue where sand started collecting at the bottom after backwashing. It was a cracked lateral in my filter. Once I replaced it, the sand stopped blowing back into the pool. Anyone else find a crack in the laterals causing this?

 

[Krzysztof Petrov]

The issue is likely a cracked lateral at the bottom of the filter. Even a small crack can let sand back into your pool.

 

[Daniel Adams]

I’ve had something similar happen. Sand getting back into the pool is usually from a cracked lateral or a gasket not sealing right. If the sand isn’t that old, that’s probably the first thing you should check.

 

[David Harris]

I agree with Zephyr to check the cheap stuff first, but a common cause right after a backwash is switching back to filter too fast while the water is still cloudy, so fine sand gets carried back before the bed “sets” again. I backwash, then do a short rinse until the sight glass runs clear, then return to filter and make sure the multiport handle fully clicks into position before the pump starts, and if it was just procedure the sand stops without opening the tank. Does the sand only show up right after backwashing, or does it appear during normal days too?