Sand / dirt coming in pool only when pump is on

rvathomas

Member
Apr 10, 2019
19
Virginia
TFP - I've posted about this before and I'm still having the same issue. I'm getting small amounts of sand and dirt in the pool ONLY when the pump is on. I figured I had a broken lateral so I replaced the sand and lateral assembly in April. That didn't fix the problem. To be sure its not algea, I have left the pump off overnight after cleaning the pool with my robot and there's nothing in the bottom. I've also kept my levels right and continually pass the OCLT.

Last week I tried something new - to rule out the lateral assembly, I put the pump in recirculate mode. Same problem - immediately dirt and sand start flowing in through the jets. It seems to happen mostly on the start and doesn't accumulate much more after the first hour of running.

How could recirculate mode be brining sand and dirt into the pool? Doesn't it completely bypass the sand and laterals?
 

pookiesunshine

Gold Supporter
May 12, 2016
598
Cincinnati, OH
With your valve in recirc turn on the pump for an hour; stop the pump, leave the valve in recirc. in a couple hours restart the pump. do you still see debris coming out the jets? if not, your valve gasket may need to be replaced. if you still see debris you may have a crack in the return line or it might still be the gasket. Does the debris come out of all return jets?
 

rvathomas

Member
Apr 10, 2019
19
Virginia
With your valve in recirc turn on the pump for an hour; stop the pump, leave the valve in recirc. in a couple hours restart the pump. do you still see debris coming out the jets? if not, your valve gasket may need to be replaced. if you still see debris you may have a crack in the return line or it might still be the gasket. Does the debris come out of all return jets?

Thanks for the reply! I'll try your suggestion. Question - with a crack in the return line, wouldn't there be a drop in pressure / air in the lines or wouldn't the pump not be able to maintain suction? I'm not seeing any of that.

And it's coming out of both return jets. I have one at each end of the pool.
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,016
Houston, Texas
Are you turning off the pump before you switch setting on the multiport valve? Are you only turning the multiport valve in one direction? Sometimes a hairline crack in the stand pipe opens up when the filter is under pressure, and it will be difficult to see when the pump is off. Check your spider gasket in the multiport valve for signs of wear or loose spots.
 

rvathomas

Member
Apr 10, 2019
19
Virginia
Are you turning off the pump before you switch setting on the multiport valve? Are you only turning the multiport valve in one direction? Sometimes a hairline crack in the stand pipe opens up when the filter is under pressure, and it will be difficult to see when the pump is off. Check your spider gasket in the multiport valve for signs of wear or loose spots.
I always turn the pump off before I switch settings on the multiport and always only turn it clockwise. I also just replaced the whole key cover assembly (includes valve and spider gasket) when I replaced the laterals (earlier this year).
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,016
Houston, Texas
I would get a tarp to put the sand on and check the stand pipe very carefully for cracks, and make sure it is seated all the wayin the filter and the multiport valve. Can you post a picutre of the filter showing the plumbing from pump to to filter?
 
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