Sand in pool after backwashing

[Vnolin]

Hi there,

I just recently discovered this forum and am so thrilled! My boyfriend and I have been living in our house for three years, and this is the first year we are having problems with our pool.

We we have a fox high velocity liter (from the 80s) and this year, things didn't seem to be filtering very well since the beginning. We changed our sand, since the old sand was basically cemented together and not very useful anymore. All fine and dandy, didn't see any broken laterals, so we were happy. Once te sand was changed, we back washed and rinsed, then started filtering. But after a while, we noticed there was sand coming out of the return line into the pool. We re-opened the filter and saw that the air relief tube was loose, so we "plugged" it back in and filtered and the sand stopped shooting back into the pool. Awesome!

Fast forward a few weeks, we backwash for the first time since fixing the air relief tube problem. After backwashing, we have sand coming into the pool again. We are now thinking broken lateral, but if one was broken, why did we stop getting sand in for a few weeks until we backwash? Does anyone have any thoughts on what the could be wrong? We checked the air relief tube and it is still "plugged" in.
Thanks in advance!

 

[domct203]

Hello and welcome to the forum.

Are you certain you used POOL FILTER sand?

Dom

 

[Vnolin]

We used Natural Rock for Swimming Pool Filtration. It was the only pool filter material they had and they said it works with all filters.

 

[dieseltim2]

I think the next step might be to take apart you multi position valve, it sounds like you might have a problem with the spider gasket, that can do all kinds of strange things, like draining water out the wash while it should be filtering, or dumping sand into the pool instead of filtering the water. Check your pressure gauge, if its reading lower then normal, you are probably just bypassing water right back into the pool and carrying sand back with it.

Tim