Sand in our pool - caused by multiport valve?


Active member
Aug 6, 2018

When we purchased our house last year, the pool inspector noticed sand in the pool. He assumed that this was caused by a broken lateral in the sand filter. We had the sellers repair this, and they went ahead and replaced the entire filter with a Hayward Pro Series S210S filter. However, I've noticed that we are still getting sand in the pool. At first, I thought it may have been from our yard. We put a large paver patio in in the early Summer, and I thought it may have been the bedding sand or paver locking sand getting blown into the pool. However, it doesn't appear that this is the case. I've read online that this could be caused by a bad multiport valve. I'm planning to file a claim with our home warranty, but I want to make sure I'm finding the issue before paying the deductible.

I believe it may be the multiport valve because the filter was already replaced, so it shouldn't be a broken lateral (unless the new one broke). There are also a few other things I have noticed that may point to a faulty multiport valve. When we haven't back washed for a bit, if I turn the pump off and back on, the pump fills with dirty water for a second before being clear again. It seems like dirty water from the filter makes it way back to the pump when I turn it on. Lastly, when we turn the pump off, the filter fills up with air. Then when we turn the pump back on, a large amount of air is pushed through the return line. It doesn't take long for the pump to fill back up with water. Only a second or two. I'm not sure if this would point to a multiport valve issue or not.

The multiport valve is a Hayward Series Vari-Flo XL.

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Thanks in advance!

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Similar discussions here have shown that the multiport can't let sand through unless maybe the pump is too large or there is too much sand in the filter. Other than those two items, it's stands to reason you may have a damaged lateral or a crack in the collector hub assembly. Much may dependo on how the new filter was installed, and how the sand was dumped-in. If not careful and filled partially with water first, a lateral could've been cracked with the new sand.

But the air issue may be from something else. I would also check the pressure gauge/air relief valve on top. If that is leaking air in, it will cause water to move in various directions and also cause the pump basket water level to drop. Not sure about your gauge, but some some have a small O-ring that you can check. While you're at it, I woudl also make sure the pump basket O-ring is clean, not defective, and lubed well to make for an airtight fit.


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
Are you sure it is sand that you have in the pool and not dead algae? It can sometimes look the same. Given that both filters have let this debris through, it seems unlikely to be a filter issue.