Could a faulty sand filter head (multi-port) push sand into the pool?

[stunatu72]

Hello. Recently noticed sand in my pool (Hayward Sand Master SM2506T filter, 12 years old). I had never replaced the sand in 12 years as the pool was clean so the technician replaced the sand and the laterals. Technician noticed when he replaced the laterals and sand, that about 20-30% of the sand was missing. After noticing sand in the pool today, I vacuumed it all and put the filter on recirculate. Sand keeps coming back. I also vacuumed last night, left the pool off, and it was clean this morning. As soon as I turn on the pump, within an hour I start noticing sand.

Pool pressure is fine (18 psi like they day it was installed), pump is running fine (no air bubbles). Only other thing I noticed this year is that when I turn off the filter, there is air in the pump. When I turn it back on the two closest jets to the equipment shot out a lot of air but the pump primes within seconds and everything looks tight afterwards.

Any ideas what could be causing this? Would a faulty multi-port head lead to sand in the pool even in recirculate? Backwash, rinse, waste all seem to be working fine. Any guidance on what to check would be appreciated.

 

[zea3]

Hi, welcome to TFP! Yes a bad multiport valve can cause this. It could also be that the wrong size sand was used, the filter was overfilled, or sand got into the stand pipe. Laterals can also be damaged when putting sand in if one is not careful. Open up the filter and check the sand level. It should have been filled up about 3/4 full with sand. After that inspect the multiport valve. There is a rubber gasket called the spider gasket inside the multiport valve. It should be firmly adhered to the multiport valve and show no signs of wear. If it is loose, torn, or worn down it will need to be replaced. Some multiport valves you can replace just the spider gasket and other brands you have to replace the whole key assembly.

 

[stunatu72]

Hi, welcome to TFP! Yes a bad multiport valve can cause this. It could also be that the wrong size sand was used, the filter was overfilled, or sand got into the stand pipe. Laterals can also be damaged when putting sand in if one is not careful. Open up the filter and check the sand level. It should have been filled up about 3/4 full with sand. After that inspect the multiport valve. There is a rubber gasket called the spider gasket inside the multiport valve. It should be firmly adhered to the multiport valve and show no signs of wear. If it is loose, torn, or worn down it will need to be replaced. Some multiport valves you can replace just the spider gasket and other brands you have to replace the whole key assembly.

Thank you for the reply. I will check everything you said. Just to confirm... if the issue is not the sand level or a broken lateral during installation, if the rubber gasket is loose/torn/worn, the filter could push sand into the pool even when in Recirculate? If the gasket is fine, then a faulty head can push sand even if backwash/rinse/waste all seem to be working fine?

Thx in advance

 

[zea3]

A bad spider gasket can prevent the valve from operating smoothly and properly. For example it may not completely seal off the chamber between filtration and waste so that water is circulating through both routes. A common sign of a bad spider gasket is water leaking from the waste port while the valve is set to filter. Having both pathways open disturbs the sand bed and some sand can be pushed out either port. Thats why you would lose a little sand instead of a ton of sand.

 

[ryandkysmom]

I’m curious as to what solved your issue. Was it just the spider gasket or bad multiport valve? I am having same issue. Hoping to just replace gaskets in multiport and not the whole thing.

 

[stunatu72]

After replacing the sand and giving it a few days, I haven’t noticed any more sand at bottom of pool. I believe it may be dead algae. I also put a sock over each return for 24 hrs and didn’t detect any sand. I will likely replace the head next year or the spider gasket just in case. Maybe tie a pantyhose over your returns to confirm it’s coming from the filter and not surface sand and debris.