Pool stubbornly cloudy after refill and SLAM

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Hi all,

I'm new to TFP after having a frustrating time delegating water testing to a store and getting yellow algae. After reading TFP's articles and doing my own testing I realized my CYA was way to high (~120) and this was probably stopping my chlorine doing anything at all. Since following TFP I've done the following:
  1. Drained the pool ~80%
  2. Refilled the pool
  3. Added Muriatic acid to lower ph to ~7.2
  4. Added liquid chlorine to quickly bring chlorine up to SLAM levels, checked levels every few hours to keep them steady
  5. Been steadily adding CYA to bring it up to a desired level (around 20 right now)
  6. Been doing daily runs of the pool robot + brushing etc, pump running 24 hours at 2350rpm
  7. Last night the pool passed the overnight chlorine test (stayed at 9ppm over night) and has less that 0.5ppm CC, so today I raised chlorine levels to the higher level for yellow algae posted here
Starting yesterday though (after starting SLAM) the pool has become cloudy and is remaining so today, despite passing the overnight chlorine test and having low CC. It's not terribly cloudy - I can just about see the bottom of the deep end (~8') - but its definitely not clear.

According to the article I only need to keep yellow-SLAM levels for 24 hours, but after that should I just maintain regular SLAM levels until the cloudiness goes? Is there any other causes of cloudiness I should be thinking about?

Thanks for your help.

pool details: 20,000 gallon, plaster, in-ground, sand filter (skimmer only, sand replaced Feb 2020)
 

duraleigh

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Welcome to the forum :wave:

Has your psi increased since you started the SLAM? What is it currently? Have you backwashed?
 

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Thanks!

PSI has not obviously changed, it's hanging around 10. I backwashed maybe a week ago, before the draining. To be honest I have doubts that the pumps pressure gauge is fully working - it definitely goes up when the pump is running, and goes up more when the pump runs faster, but it doesn't show a steady increase over days/weeks of use and backwashing does not clearly lower the PSI.
 

IceShadow

Gold Supporter
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Jun 8, 2019
2,177
Milwaukee, WI
Sand filters take the longest to clear. How long since the water was cloudy blue?

Be sure to check light niches, skimmer throats, removable ladders / steps for algae hiding.
 

duraleigh

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I would suggest holding it at SLAM value for another 24 hours and report back. A pic would help a lot.
 

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Thanks both.

It's been cloudy for ~36 hours, but I was surprised that the cloudiness was persisting even though chlorine levels are stable overnight. Could the cloudiness just be dust kicked up by my brushing? The robot is definitely collecting plenty of sludgey grime every time it runs.

I'll keep an eye on chlorine levels and report back in 24 hours with a photo.
 

Richard320

TFP Expert
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Jan 6, 2010
23,925
San Dimas, CA (LA County)
You know what jumped out at me? "sand filter skimmer only."

You may be suffering from poor circulation. And just how fine is the bag on the robot? I'll bet it doesn't filter as well as a filter. You don't happen to still have an old manual vacuum and hose laying around, do you? Maybe suck the dirty water up from the depths instead of the surface so the filter can grab it all.

Second idea: improve filtering. A little DE or cellulose in your filter will improve the filtration a lot. So much so that you better be home to keep an eye on it because it'll load up and need backwashing in an hour or two. Add DE to a Sand Filter - Trouble Free Pool
 

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Thanks, yes, the skimmer-only is a total hassle. A previous owner cemented up the main drain so I assume it was leaking at some point.

I do have a manual vac though need more practice getting it to work; whenever I connect it to the skimmer the pump loses prime, so air must be getting in to my pipe somewhere. But I'll spend more time with it. The robot is the dolphin nautilus plus with the extra fine filters. It grabs a lot of small stuff, but not everything because you can see it venting ultra fine particles as it runs. Still, the pool was super clear last year, so the combination of filter and robot can do it. I'll run the robot 2-3 times tomorrow, see if that helps.

Thanks for the article on DE in sand filters, I'll try that if there's no progress in a couple of days, though it sounds a little intimidating!
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,177
Milwaukee, WI
36 hours isn’t too crazy. I’ve seen reports of people who can take a week or more to clear a pool with a sand filter. It’s just patience and time.
 

wireform

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Aug 15, 2017
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Spring Valley, NY
Your robot is kicking up the stuff and causing it to be waterborne. That's where the cloudiness is from. Use a hose, connect it to the skimmer port and vacuum the complete pool floor into the filter. When psi rises 25% of clean filter pressure that's the time to give it a good backwash. Contrary to belief a dirty sand filter actually helps filter the water up to a point.
 
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tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Reporting back with photos

Here's the shallow end:
YudtO2jOTV6ywTVgrphIOg.jpg

And the deep end (note you can just about see the capped main drain at the bottom, its more visible by eye)
skzbWzUiSFG+HWzLhUlu+w.jpg

The pool is still pretty cloudy, and it failed the overnight chlorine test (dropped from 17ppm to 15pmm). It's had 24 hours at mustard-SLAM now though, so I'll let it drop back down to regular SLAM until the cloudiness clears. I'll try letting the dust settle over night and vacuum tomorrow morning. Though let me know if anything looks amiss.

Thanks again!
 

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Thanks! Sorry, I should have been clearer. The pump is absolutely running 24/7, but the dust in my pool has no problem settling on the bottom even with the pump running. Perhaps because we have only a skimmer and so poor circulation.
 

Flying Tivo

Well-known member
Jan 24, 2017
1,889
Monterrey, NL, Mexico
Since you mentioned that you followed poolstores recommendations, did you ever add clarifiers to the pool? If you did, then you needed to do a Deep cleaning of the sand in your filter. Since its chap you might even exchange it for new, so you have a fresh start with TFP method.
 

duraleigh

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Sebring, Florida
Letting the "dust" settle is much more problematic than brushing it up into the properly chlorinated water and allowing your filter to get it out
 

tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Since changing the sand, and before draining the pool and starting on the TFP method, I've added a lot of powdered shock and a little of Leslie's "perfect weekly", but probably only 2 cups since changing the sand.

Duraleigh, thanks, I'll keep brushing and filtering then. The FC dropped overnight from 14.5 to 13, so that suggests it's still working on something.
 

duraleigh

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I think that's a good plan. It may make it even cloudier at first but that is temporary. Again, get that debris OFF the pool floor and into you filter. backwash anytime psi gets 25% above normal.
 
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Flying Tivo

Well-known member
Jan 24, 2017
1,889
Monterrey, NL, Mexico
Since changing the sand, and before draining the pool and starting on the TFP method, I've added a lot of powdered shock and a little of Leslie's "perfect weekly", but probably only 2 cups since changing the sand.
You can also try to slow down your pump from 2350rpms to something like 1250-1350, the slower the flow on the filter, the more it can catch.
 
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tjhm4

Member
May 3, 2020
13
Phoenix, AZ
Hi all, a quick update incase anyone else comes across this thread. I kept at it for a couple more days but cloudiness persisted so I followed Richard's advice and added DE to the sand filter. As predicted PSI rose pretty quickly (first batch needed backwashing in ~2 hours, then ~4 hours, then ~12 hours) but the pool cleared extremely fast. After 4 rounds of DE the pool is now crystal clear, OCLT is passing and there's no CC so I am ending my SLAM and aiming to be in the pool by tomorrow afternoon. Thanks all for your help!