Fighting Cloudy Water - Chemicals all see good

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teesee151

Member
Feb 18, 2022
8
Michigan - Indoor Pool
Been a long time reader and have solved many issues thanks to this forum, but I'm currently stuck on one and can't figure it out. This is my dads pool but I usually help keep everything in check.

Pool info: 20,000 gallon Indoor fiberglass pool in Michigan, pool room temp is 70*. Sand filter. Filter pump runs 8 hours a day. It has been several years since sand was replaced. Not sure if this is an issue or not. Using chlorine tablets to keep pool chlorine levels in check and liquid chlorine to shock if needed. I use drop tests for all my testing and all my tests are brand new except for the TA. Pool is 20-21 years old.
FC is currently at 3, but I've had it up to 5 with same results
CC is 0, ph level is 7.5
CYA is under 20, I can still see the black dot in the bottom of the tube with water all the way to top.
TA is 110.
I recently had my pool drained about 50% to fix a leak. Filled it back up with my well water which I always have done in the past. This time I've been fighting cloudy water ever since I filled it back up. I started this problem with ph about 7.8-7.9 and have had it down to 7.5 for about two weeks. I've shocked the pool to between 10-12 free chlorine a couple times with no improvements either.

This one is really throwing me as usually if all my chemicals are in balance, I don't have cloudy water, and if I do, a overnight shock usually fixes it. My dad used to obsess over phosphate levels in the pool (courtesy of the local pool store) but once I got him to ignore those, I've never checked them and don't believe they have caused any problems. FC is staying steady as I expect and doesn't seem like its dropping. Today if the first day in about a week since I've been able to get over and check the pool and the chlorine tablets were actually out and still holding a FC level of 2.5.
 
Welcome to TFP! :wave: Which drop testing are you using specifically? We recommend using either a TF-100 or Taylor K-2006C kit that contains the FAS-DPD powder & drops for accurate FC testing. A few things catch my eye:
1 - How long has it been since the sand was deep cleaned?
2 - If the pool usually has tabs in use, it seems odd the CYA is only <20. Very odd.
3 - Has anyone added liquid bleach that has fabric polymers (i.e. Clorox), or scented/splashless products?
 
Texas Splash said:
Welcome to TFP! :wave: Which drop testing are you using specifically? We recommend using either a TF-100 or Taylor K-2006C kit that contains the FAS-DPD powder & drops for accurate FC testing. A few things catch my eye:
1 - How long has it been since the sand was deep cleaned?
2 - If the pool usually has tabs in use, it seems odd the CYA is only <20. Very odd.
3 - Has anyone added liquid bleach that has fabric polymers (i.e. Clorox), or scented/splashless products?
Click to expand...

Using the TF-100 test kit. Also have a couple separate Taylor test kits for Chlorine/Ph. I used each different kit today for ph and FC and got the same results.

1) Not sure. Sand filter was at 20psi and I just backwashed it for 2 min, rinsed for 1 min, and then returned back to filter operation and it was still at 20psi.
2) I've never had high CYA or I'm doing something wrong with the test but when I fill the cylinder up with pool water, it looks like I'm looking thru clear water and the black dot at the bottom of the cylinder is still crystal clear to see.
3) We only use the tabs and the 12.5% liquid chlorine from the pool store. My dad and I are the only ones that add chemicals so nothing else is being used.

I bought the FC up to 10 again before I left to try another overnight shock. I'll run by again tomorrow and see if the FC held overnight.
 
Well, if we put the sand issue to the side for now, you might consider doing an Overnight Chlorine Loss Test to see if there is any excessive FC loss due to organics. It's strictly to check FC loss since we know the sun's UV is not a factor for this pool. The trick is being there for one night to help do the FC tests. If you pass the OCLT, then it may be time to do a sand deep clean.
 
Hey Tee and Welcome !!!!

teesee151 said:
I've never had high CYA or I'm doing something wrong with the test but when I fill the cylinder up with pool water, it looks like I'm looking thru clear water and the black dot at the bottom of the cylinder is still crystal clear to see.
Click to expand...
*fill with pool water and CYA mix, correct ?
teesee151 said:
We only use the tabs and the 12.5% liquid chlorine from the pool store. My dad and I are the only ones that add chemicals so nothing else is being used
Click to expand...
Each tab adds 3 or so CYA for 20k gallons. You are adding it but not seeing it in the test, hence my question above.
 
teesee151 said:
Using the TF-100 test kit. Also have a couple separate Taylor test kits for Chlorine/Ph. I used each different kit today for ph and FC and got the same results.

1) Not sure. Sand filter was at 20psi and I just backwashed it for 2 min, rinsed for 1 min, and then returned back to filter operation and it was still at 20psi.
2) I've never had high CYA or I'm doing something wrong with the test but when I fill the cylinder up with pool water, it looks like I'm looking thru clear water and the black dot at the bottom of the cylinder is still crystal clear to see.
3) We only use the tabs and the 12.5% liquid chlorine from the pool store. My dad and I are the only ones that add chemicals so nothing else is being used.
Click to expand...

Texas Splash said:
Well, if we put the sand issue to the side for now, you might consider doing an Overnight Chlorine Loss Test to see if there is any excessive FC loss due to organics. It's strictly to check FC loss since we know the sun's UV is not a factor for this pool. The trick is being there for one night to help do the FC tests. If you pass the OCLT, then it may be time to do a sand deep clean.
Click to expand...

I'm doing an OCLT right now. Will report back tomorrow.

Just looked up a deep cleaning on the sand filter. We have never done that. We also don't get much gunk in the pool but I'll see if I can get someone to help move the sand filter outdoors tomorrow and see if I can do a deep clean too.
 
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Newdude said:
Hey Tee and Welcome !!!!


*fill with pool water and CYA mix, correct ?

Each tab adds 3 or so CYA for 20k gallons. You are adding it but not seeing it in the test, hence my question above.
Click to expand...

From what I remember, there is a small bottle included with the test kit, fill the bottle with pool water to the bottom of the label, then add the test solution to the top of the label and mix and let sit for a few minutes. Then pour it into the small skinny cylinder with the black dot at the bottom until you can't see the black dot at waist level.
 
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Ok great !!!! Just the way you said you filled it with pool water. Wanted to make sure.

Are you doing the test outside in full sun (behind you). That makes a difference that you may be missing with the indoor pool. Most of us are already outside when we get our sample.
 
Newdude said:
Ok great !!!! Just the way you said you filled it with pool water. Wanted to make sure.

Are you doing the test outside in full sun (behind you). That makes a difference that you may be missing with the indoor pool. Most of us are already outside when we get our sample.
Click to expand...

I am indoors when I do the test but I see zero difference in the black dot. My black dot looks just like the Begin Test pic below.
I'll do the test again tomorrow in the sun and see if I get a different result.

CYA EndPoint.png
 
teesee151 said:
I'll do the test again tomorrow in the sun and see if I get a different result
Click to expand...
It may still be low, but do it outside from now on either way. Even when its great this test befuddles us all. No need to make it worse. Lol.

Also, your indoor pool is basically an full time OCLT. A few rays of sunshine through the nearest window probably wont do much. I suspect the tabs were hiding your FC loss. With next to no UV, you should have easily gained FC, not held steady. But we'll see in the morning.

I also want to 2nd the deep clean Pat mentioned above. Its not a problem, until it is, but if you cant remember the last time, its closer to the next time. Probably loooooong past it too. Here is the go-to thread. The bottom of the first post has video links. Deep Cleaning a Sand Filter
 

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Just tested for the OCLT. Had a loss of maybe .5 FC. Did the test a couple times and keep getting within 1 drop of where I was last night. I keep getting between 19 and 20 drops to go clear on the drop test. I was at 20 last night when I left. Zero CC

Tested CYA again and went outside in direct sunlight. Filled the test tube all the way and the black dot was just barely starting to lighten up. I spun around in several directions and the dot did not change. Definitely under 20 for CYA.

Really appreciate everyone's input. Looks like I'm down to the sand filter.

I've attached a pic of the current pool status. Normally I have no problem seeing the tile dolphin or the drain at the bottom.20220219_132326.png
 
I found some Omni Filter Aid so I added enough to bring the filter pressure up 1psi. It's cellulose instead of DE but looks like it should accomplish the same goal. Going to let everything run for 24 hours while keeping the water at shock level then backwash and see what happens. Hoping it helps as I can't do a deep clean on the sand filter right away.
 
teesee151 said:
Just tested for the OCLT. Had a loss of maybe .5 FC. Did the test a couple times and keep getting within 1 drop of where I was last night.
Click to expand...
OK so it's not an organic / living thing as the FC held.

The next 2 choices are the filter and metals that are coming out of solution at the right FC / PH combo. Errrr... wrong combination cuz its making you see them.

Metals removal is quite the process, many threads on it if you search for removing iron/copper. But the test is SIMPLE. Hit up the pool store and put thay free test to good use for the first time ever. They are actually pretty ok for a metals test. Just don't buy any magic potions that they reccomend. You 'happen to have some of that at home already' and thank them.

I'm gonna go with filter tho because usually with metals, it's perfectly clear, just tinted. Yours is definitely cloudy. It might not be the sand but the stand pipe inside could be dislodged or broken, blowing crud right back into the pool like the sand doesn't exist.
 
Newdude said:
OK so it's not an organic / living thing as the FC held.

The next 2 choices are the filter and metals that are coming out of solution at the right FC / PH combo. Errrr... wrong combination cuz its making you see them.

Metals removal is quite the process, many threads on it if you search for removing iron/copper. But the test is SIMPLE. Hit up the pool store and put thay free test to good use for the first time ever. They are actually pretty ok for a metals test. Just don't buy any magic potions that they reccomend. You 'happen to have some of that at home already' and thank them.

I'm gonna go with filter tho because usually with metals, it's perfectly clear, just tinted. Yours is definitely cloudy. It might not be the sand but the stand pipe inside could be dislodged or broken, blowing crud right back into the pool like the sand doesn't exist.
Click to expand...

I just ordered all the parts to rebuild my sand filter. I know one or more of the laterals is cracked as I've been getting a bit of sand in my pool for years but never enough to be that bothersome. Going to replace the whole lateral assembly, variflow valve as it leaks really bad on bypass mode, oring, clamp and put in new sand. Hopefully that'll take care of the couple small problems we have and fix the water too.

I'll take a water sample to the local pool store too just to be sure.

Again, thanks for the help!
 
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