High CYA, first time LC user

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bja1288

Well-known member
Mar 28, 2022
56
Ozark, MO
Pool Size
22000
Surface
Vinyl
Chlorine
Liquid Chlorine
This is my 3rd season as a pool owner. Pool details in signature. I have been using tabs with a feeder (2 tabs/week) and 2lbs granular shock / week up to this point. My CYA last read by Leslie's was 117 on 6/12. Ever since I've owned the pool, my chlorine readings have always been low: 0-0.5 FC. I never got around to dealing with it because the water was crystal clear. Well now it has started to get cloudy - I can barely see the drain in the deep end as of yesterday. I assume this is due to a combination of high CYA, me not paying close attention to when pucks run out, and only running the filter ~8-10 hours a day.

I've been wanting to switch to LC, so I figure this is the time. I turned off my feeder and put in 2 gallons of 12.5% bleach this morning when my readings were 0 FC, 0 CC. That took it to 5.5 FC, 4.5 CC. I added 1 more gallon and an hour later measured 9 FC, 4.5 CC. Other measurements are 7.2 pH, 120 TA, 120 CYA (although that may be a bit off because the test kit only goes to 100, haven't done the diluted test yet).

So is there a chance I can get this under control with just LC or should I begin draining and refilling the pool to control CYA instead of wasting LC? I'm aware of the dangers of total draining so I would do it in pieces but not sure how much to do at a time. If the water clears up with just LC, can I just leave it? I'm also curious what will happen to the CC - will it decrease as time goes on, and that will be a sign of successful fighting of whatever is brewing?

Thanks in advance for the help.
 
Are you doing the CC test correctly? It seems awfully high - especially if you only have some cloudiness.
It would be best to drain water.
One way is to drain from deep end and add water at surface, or drain from surface and add water to deep end. Depends if you have a main drain (maybe not because you have vinyl pool). So pull water from your skimmer to waste via your pump and put hose weighted down in the deepest part.
Or you can use a sump pump to drain from either deep or shallow end.
 
HermanTX said:
Are you doing the CC test correctly? It seems awfully high - especially if you only have some cloudiness.
It would be best to drain water.
One way is to drain from deep end and add water at surface, or drain from surface and add water to deep end. Depends if you have a main drain (maybe not because you have vinyl pool). So pull water from your skimmer to waste via your pump and put hose weighted down in the deepest part.
Or you can use a sump pump to drain from either deep or shallow end.
Click to expand...
I think I did it correctly considering I got 4.5CC twice and followed the instructions included with the TFP Pro test kit. I will test again tonight. I have 1 main drain and 1 skimmer both at the deep end. I assume I should drain to waste and then fill from the shallow end. Should I only drain to bottom of skimmer so I can continue using it? Or go below skimmer and depend on the main drain for filtering? I think my filter struggled priming last time I tried shutting off my skimmer but I could try again.
 
WaarrEagle said:
Sounds like we are on the same journey for the same reasons (high CYA). See my recent post and replies: New Pool Owner Worried about High CYA

I will be running an OCLT this evening to help decide my path forward. I suspect I will fail and end up draining.
Click to expand...
Ah nice, thanks for the link. Will follow your adventure. I think I'll go ahead with drain/refill. Just need to decide on the specifics of that.
 
Do the diluted cya test so u have an accurate starting point.
Here’s the ins & outs of water exchange options 👇

Draining - Further Reading

www.google.com www.google.com
Dipping below minimum for your cya as well as cloudy water points to algae & unsanitary water. You can do an Overnight Chlorine Loss Test to confirm this.
The SLAM Process is necessary to eradicate algae & clean up the water.
You will know when algae is eradicated/pool is sanitary & maintenance fc levels can be resumed by meeting ALL 3 end of Slam criteria as listed in the article. A clear pool is only one of the criteria.
 
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Mdragger88 said:
Do the diluted cya test so u have an accurate starting point.
Here’s the ins & outs of water exchange options 👇

Draining - Further Reading

www.google.com www.google.com
Dipping below minimum for your cya as well as cloudy water points to algae & unsanitary water. You can do an Overnight Chlorine Loss Test to confirm this.
The SLAM Process is necessary to eradicate algae & clean up the water.
You will know when algae is eradicated/pool is sanitary & maintenance fc levels can be resumed by meeting ALL 3 end of Slam criteria as listed in the article. A clear pool is only one of the criteria.
Click to expand...
Diluted test showed 120 (60 doubled). I am doing the no drain water exchange. Temperature difference is roughly 20 degrees so I have fill hoses in the deep end and pump in the shallow end. When it says to fill in the deep end should the hose be at the top of the water or the bottom? And if it is the bottom, is it okay to submerge my pre-filter attached to the hose?

Thanks again.
 
bja1288 said:
Diluted test showed 120 (60 doubled). I am doing the no drain water exchange. Temperature difference is roughly 20 degrees so I have fill hoses in the deep end and pump in the shallow end. When it says to fill in the deep end should the hose be at the top of the water or the bottom? And if it is the bottom, is it okay to submerge my pre-filter attached to the hose?

Thanks again.
Click to expand...
The goal is to get rid of existing water with CYA and not the fresh water you are adding. so if you have a submersible pump on the shallow end (I am assuming 3.5 ft-4ft of water?) then the fill hose at the deep end can be at the top.
Try to balance outflow to waste with inflow from fill line so you may have to stop your pump if it is outrunning your inflow hose.
 
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Alright, after 46 hours of 4.1 gpm out and 4.1 gpm in with the filter off, I stopped. The pool actually looks better than I started, basically no cloudiness. I've got filter running and the dolphin. Here are new measurements after 1 hour of filtering:

CYA: 60
FC: 0.5
CC: 1.5
pH: 7.5
TA 150

I assume I need to get the TA under control before adding LC for the OCLT. I have never added muriatic acid before, will have to buy it. The previous owner left a tiny bit, maybe 8 ounces. It is probably at least 3-4 years old at this point. Can I pour that in just to get rid of it? I assume I should target pH of 7 and then I will point my returns up to aerate.
 

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If you're new at testing the TA can also be high for testing error if the reagents are new.
  • Sometimes a static electric charge can build up on the R-0009 dropper bottle tip, causing the drops to be smaller than usual and making the test read higher than actual. You can prevent this by wipping the tip of the dropper bottle with a damp cloth or tissue before you start and after each drop.
  • Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
 
jeffchap said:
Forget about TA until after the SLAM. It's always the last thing we worry about. It's simply not that important.

What are your FC and CC after the drain?
Click to expand...
Posted it above, copy-pasting here. I had the pump off for the 46 hour drain/refill and this is 1 hour after turning on the pump:

CYA: 60
FC: 0.5
CC: 1.5
pH: 7.5
TA 150
 
Yeah, you need to begin a SLAM ASAP. Your target FC is 24. Everything else is okay to begin. Just start adding chlorine. You don't even need to waste reagents measuring CC any more until the water is perfectly clear.
 
jeffchap said:
Yeah, you need to begin a SLAM ASAP. Your target FC is 24. Everything else is okay to begin. Just start adding chlorine. You don't even need to waste reagents measuring CC any more until the water is perfectly clear.
Click to expand...
At this point I’d say the water is perfectly clear now that the pump has been running for 3 hours. Think I should still SLAM based on the CC?
 

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