Please help with sand returning to pool!

suerou

Active member
Jun 25, 2018
35
Charlton ma
Good morning! I currently have sand returning to my pool through return lines. 2019 I replaced sand in filter. May of 2020 emptied sand and inspected laterals and bought new laterals due to some cracks and corrosion. Refilled with sand and subsequently had sand return to pool. May of this year I emptied sand filter again to make sure all lateral arms were pushed down and that no damage was present. Took lateral to local pool store where I bought it (good people) for them to eyeball. No damage found. Put it back and bought new sand to be sure the size of sand was correct. Running the pool and sand is present again on the bottom of return side of pool. Ugh! My pool is 5 years new to me (former owners did not care for it well). So here is the big question, any chance the sand is getting pulled into the pool because of the multiport valve? Thats the only thing I can figure out at this point. When I put the laterals back I did so very carefully and added water before gently scooping 200lbs of sand in so I know its nothing that happened when I put it back together. I appreciate any feedback. Thanks!!!
 

cj133

Well-known member
May 6, 2018
483
NJ
Good morning! I currently have sand returning to my pool through return lines. 2019 I replaced sand in filter. May of 2020 emptied sand and inspected laterals and bought new laterals due to some cracks and corrosion. Refilled with sand and subsequently had sand return to pool. May of this year I emptied sand filter again to make sure all lateral arms were pushed down and that no damage was present. Took lateral to local pool store where I bought it (good people) for them to eyeball. No damage found. Put it back and bought new sand to be sure the size of sand was correct. Running the pool and sand is present again on the bottom of return side of pool. Ugh! My pool is 5 years new to me (former owners did not care for it well). So here is the big question, any chance the sand is getting pulled into the pool because of the multiport valve? Thats the only thing I can figure out at this point. When I put the laterals back I did so very carefully and added water before gently scooping 200lbs of sand in so I know its nothing that happened when I put it back together. I appreciate any feedback. Thanks!!!

Personally I can't see the multiport causing sand to get into the pool. All of the pressure should be downward when in filter mode.

Are you 100% sure it's sand?
 

suerou

Active member
Jun 25, 2018
35
Charlton ma
Hi thanks for the reply. Yes it's sand. At the end of last pool season (august/september) I was getting it in the pool. I decided to wait until the start of this season to shop vac out the dry sand and check the laterals again. After inspecting the laterals and purchasing new sand and double checking that my filter takes I can't think of anything else that would send the sand back in. I'm stumped on this one.
 

cj133

Well-known member
May 6, 2018
483
NJ
Hi thanks for the reply. Yes it's sand. At the end of last pool season (august/september) I was getting it in the pool. I decided to wait until the start of this season to shop vac out the dry sand and check the laterals again. After inspecting the laterals and purchasing new sand and double checking that my filter takes I can't think of anything else that would send the sand back in. I'm stumped on this one.
If it's sand and not algae the only way I can imagine it getting in is bad laterals, or a crack or bad connection to the center pipe.

Did you fill it half way with water before dumping the sand in?
 

borjis

LifeTime Supporter
Aug 19, 2014
3,491
Pacific NW
Sometimes a lateral can be cracked but invisible in viewing. Rare but it can happen.

You've been very careful though so I'm not sure what it could be otherwise.
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
14,031
Houston, Texas
Have you inspected the multiport valve? Check and make sure the spider gasket is intact without signs of excessive wear. When the pool is running is it a constant stream of sand or just a puff when the pump comes on? Are you seeing water come out of the waste line when the multiport valve is set to filter? Did you check that the multiport valve was plumbed correctly?
 
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CrystalRiver

Well-known member
Jun 19, 2020
648
Massachusetts
Check that the MPV is plumbed correctly. Having the pump connected to the return fitting and vice versa could put sand in the pool. The water would be running backwards through the filter.
 

suerou

Active member
Jun 25, 2018
35
Charlton ma
Always appreciate everyone's feedback. Thanks so much. I did fill the filter with a good amount of water and then added sand very carefully (pipe covered). The multiport valve is older. Handle is tough to move sometimes. Often I can hear gurgling near it and I am not convinced it always works properly. I will take it apart to look at the spider gasket. The sand continuously comes into the pool, not just in a puff. At the end of last season I hung a nylon stocking over the returns to see if sand filled them and it did. With the new lateral last May and new sand this year I can only imagine it has something to do with the valve but wanted to hear from others with more experience. Thanks again, I will be on the valve tomorrow to see if I can figure it out.
 

suerou

Active member
Jun 25, 2018
35
Charlton ma
On a side note I have been in this property for about 5 years and last year was the first with sand so I am hoping all is plumbed properly, however that's my next guess if its not the valve. Thanks again.
 

jdegraeve

Member
Jun 14, 2021
9
Rochester, NY
Hi - just checking on this, was it ever resolved? I've got the same type of issue and I can't seem to figure out what happening. Took the entire system apart the other day, inspected everything and found nothing wrong with laterals or stand pipe. Still getting lots of sand in the pool. Let me know if you have some words of wisdom on this, thanks!
 

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