HELP: Cannot figure out how sand is getting in pool

rvathomas

Member
Apr 10, 2019
16
Virginia
TFP - I am at my wit's end. I've had sand coming back into my pool for the last year. After doing lots of research on this site, I decided to do the following:

First, I replaced the key cover and handle assembly. I did this because I had taken off the old key cover and the spider gasket looked pretty worn down. I figured this could be the cause - if the spider gasket wasn't sealing the ports maybe sand was coming through that way. That didn't solve the problem.

Next, today I decided to go ahead and replace the lateral assembly. I also put in new sand (HTH pool sand) just because I didn't want to have to figure out how to get the old sand back in.

After doing that, I'm still seeing the same problem. When I run the filter, sand gets thrown all around the pool. It's clearly sand on the steps. On the bottom it does kind of look like dead algae but it can't be algae because it only comes out when the filter is running. I can vacuum the pool with my Dolphin S200 then leave the filter off overnight and there's nothing on the bottom. Then after an hour of running the pump there's sand / black stuff back on the bottom, and it's more concentrated around the jets. Also it feels gritty and I can actually capture it on the steps. But it's not a lot of sand - I've heard w/ a broken lateral it will dump mounds of sand on the bottom - this is small amounts throughout the pool.

I test religiously using the Taylor TF-100 kit and follow the TFP method for keeping my pool sanitized. Current levels:
FC: 6.5
CC: < 0.5
CYA: 30
pH: 7.4
TA: 110

Also, last night FC was 7.0, so only 0.5 PPM loss overnight, which again indicates it's not algae.

What else could possibly be causing this??? Any help greatly appreciated!
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,602
San Dimas, CA (LA County)
It sounds like you had the wrong size sand or a crack somewhere. Now it might just be residual sand stuck in the plumbing getting pushed out. Rubber band a sock around the return if you can and it will save you vacuuming. In a couple days it should clear out.
 

rvathomas

Member
Apr 10, 2019
16
Virginia
It sounds like you had the wrong size sand or a crack somewhere. Now it might just be residual sand stuck in the plumbing getting pushed out. Rubber band a sock around the return if you can and it will save you vacuuming. In a couple days it should clear out.
Thanks for the reply! That would be amazing if you're right. It had to have been a crack - haven't touched the sand in years. I couldn't find a crack in the old assembly, but I did crack the pipe when I took it out to put the new one in. I didn't think about residual sand still coming out. Fingers crossed it clears out in a couple of days.
 

rvathomas

Member
Apr 10, 2019
16
Virginia
It sounds like you had the wrong size sand or a crack somewhere. Now it might just be residual sand stuck in the plumbing getting pushed out. Rubber band a sock around the return if you can and it will save you vacuuming. In a couple days it should clear out.
Richard / all,

Unfortunately, it's been a week and I'm still seeing sand come in the pool when the filter is running. It's not a lot of sand, but it's still frustrating as it spreads all over the bottom and looks terrible. Any other ideas on how this could have happened? I checked the new laterals meticulously and they were good. I was also super careful pouring in the new sand - even bought the $10 cardboard sand shield to hold the lateral assembly in place and keep sand out of the stand pipe. And as I mentioned before, earlier this year I replaced the whole key cover and handle assembly so I have a new spider gasket.

One thing I haven't done is backwash & rinse since I added the new sand (because the pressure hasn't gone up enough). Is there any way that could fix this problem??
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,602
San Dimas, CA (LA County)
Richard / all,

Unfortunately, it's been a week and I'm still seeing sand come in the pool when the filter is running. It's not a lot of sand, but it's still frustrating as it spreads all over the bottom and looks terrible. Any other ideas on how this could have happened? I checked the new laterals meticulously and they were good. I was also super careful pouring in the new sand - even bought the $10 cardboard sand shield to hold the lateral assembly in place and keep sand out of the stand pipe. And as I mentioned before, earlier this year I replaced the whole key cover and handle assembly so I have a new spider gasket.

One thing I haven't done is backwash & rinse since I added the new sand (because the pressure hasn't gone up enough). Is there any way that could fix this problem??
It's worth a try. There may be a bunch of too-fine sand in the blend. Maybe a backwash will disturb it and get it flushed out.
 

czipper

LifeTime Supporter
May 12, 2014
87
Long Island, NY
I thought that I had sand coming into the pool once when I replaced a DE filter wtih a sand filter, but the pool company came out and looked at it wasn't the same as the sand from the filer (zeobrite). We figure it must be local raccoon population (we have a TON) who I know like to frequent my pool at nightime to wash themselves or the food they are digging out of the very sandy soil where we live. Sounds weird, but its really the only explanation that makes sense.
 

rvathomas

Member
Apr 10, 2019
16
Virginia
I thought that I had sand coming into the pool once when I replaced a DE filter wtih a sand filter, but the pool company came out and looked at it wasn't the same as the sand from the filer (zeobrite). We figure it must be local raccoon population (we have a TON) who I know like to frequent my pool at nightime to wash themselves or the food they are digging out of the very sandy soil where we live. Sounds weird, but its really the only explanation that makes sense.
Wow, weird. In this case, I know it's the filter because when I vacuum at night and then leave the pump off, there's no sand in the morning. Sand only accumulates when the pump is running. Yesterday I trapped it in a pool skimmer sock - very little, but it looks so bad across the bottom of the pool.
 

rvathomas

Member
Apr 10, 2019
16
Virginia
How old is the pool and is anything under warranty?
The pool came w/ our house. It's ~10 years old. No warranties on anything that I know of. I replaced all the parts of the sand filter myself.

I did the backwash and rinse step, and that still hasn't solved the problem. Sand still coming in. Not much, but enough to make the bottom look dirty after running the pump for ~ 1 hour.

I'm very frustrated and have run out of ideas to fix this.
 

Homebrewale

Well-known member
Apr 21, 2020
68
Apex, NC
Have you taken off the cover since you put everything back together? I had sand getting into my pool at one time after replacing the laterals. What happened is that when I put the top of the sand filter on, I didn't have everything lined up perfectly. I cracked the top of the vertical center pipe.
 

rvathomas

Member
Apr 10, 2019
16
Virginia
Here's another theory - the new multiport valve handle has play when it's set to a particular setting (e.g. filter, backwash, rinse). It has tension when I move between settings, but the handle is visibly loose when it's on a setting. Could it be that the new multiport is defective or it's not seated right? It doesn't seem like there's enough sand to be a broken lateral - a little bit collects in a skimmer sock when i vacuum after hours of the filter running. Looks like broken / improperly seated laterals dump a lot of sand in the bottom.

Has anyone had experience with a new multiport not being seated properly leading to sand in the pool? It's not leaking out of the waste port though...