Chlorine disappearing overnight

Kk88pool

New member
Mar 26, 2021
3
Florida
Salt pool, 13k gallon, Florida, water at 88 degrees. blue solar cover.
Chlorine won't stay. Easy to maintain for past 10 years. Not anymore.

Chlorine is at 0 (total, combined and free)
Ph 7.4
Alkalinity 110
Calcium hardness 320
Stabilizer 0
Total dissolved solids 4500
Salt 3100
Phosphate 0

4 weeks ago added a gallon of stabilizer (cyanuric acid). Did nothing. 2 weeks ago added 4lbs dry stabilizer (cyanuric acid}, did nothing. Now they want me to add a gallon of liquid chlorine and 6lbs of stabilizer. Salt cell is generating chlorine as I take a reading at the jet. Yesterday pool read 1ppm chlorine and Jerry was putting it 2ppm. Running generator at 100% for 8 hrs per day. Haven't been adding much water, maybe an inch over the last month, and it hasn't rained.

Any suggestions would be so appreciated.

Thank you,

Kevin
 

Kk88pool

New member
Mar 26, 2021
3
Florida
Salt pool, 13k gallon, Florida, water at 88 degrees. blue solar cover.
Chlorine won't stay. Easy to maintain for past 10 years. Not anymore.

Chlorine is at 0 (total, combined and free)
Ph 7.4
Alkalinity 110
Calcium hardness 320
Stabilizer 0
Total dissolved solids 4500
Salt 3100
Phosphate 0

4 weeks ago added a gallon of stabilizer (cyanuric acid). Did nothing. 2 weeks ago added 4lbs dry stabilizer (cyanuric acid}, did nothing. Now they want me to add a gallon of liquid chlorine and 6lbs of stabilizer. Salt cell is generating chlorine as I take a reading at the jet. Yesterday pool read 1ppm chlorine and Jerry was putting it 2ppm. Running generator at 100% for 8 hrs per day. Haven't been adding much water, maybe an inch over the last month, and it hasn't rained.

Any suggestions would be so appreciated.

Thank you,

Kevin
Also, I used to have to add 16oz of muriatic acid regularly every week for the past 10 years. Now pH remains stable or occasionally drops to 7.2 them returns to 7.4 on it's own. Never goes up to 8.2 like it used to. Seems to drop at the same time chlorine is at 0.
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,490
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Welcome to TFP!

How are you testing the pool water? When did the CYA stop showing up?
 

Kk88pool

New member
Mar 26, 2021
3
Florida
Welcome to TFP!

How are you testing the pool water? When did the CYA stop showing up?
I test it with oto drops 5 basic test. I also use strips that show the cya but mainly I have water tested at local pool store. Can I name pool store here? Pool store said to add Cya. I never used to put any in because I have swg for 40k pool and my pool is 13k, so it easily kept up without adding cya. I've only added it starting last month but it never goes up.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
21,145
Bedford, TX
88,

How old is your cell???

You should take a read through our Pool School as we do stuff a lot differently than Pool $tores.. Pool School - Trouble Free Pool

If your pool uses chlorine after dark, that usually means you have an algae bloom, even if you can't see it yet.. It is pretty hard to test this theory if you are only running your FC at 1 ppm..

We have a test, called an Overnight Chlorine Loss Test (OCLT) where we have you test your FC level right at sundown and again right at sunup... The two values should be pretty much the same. If not, something is eating your chlorine and if it is not the sun, then it has to be algae.

See this link.. Overnight Chlorine Loss Test

Thanks,

Jim R.
 
Last edited:

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,588
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
We have a test, called an Overnight Chlorine Loss Test (OCLT) where we have you test your FC level right at sundown and again right at sunup...

... with your SWG off.
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,490
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
I test it with oto drops 5 basic test. I also use strips that show the cya but mainly I have water tested at local pool store. Can I name pool store here? Pool store said to add Cya. I never used to put any in because I have swg for 40k pool and my pool is 13k, so it easily kept up without adding cya. I've only added it starting last month but it never goes up.
Doesn’t really matter what pool store, we don’t trust any of them around here. Their test results have been shown to be fairly unreliable.

For example, you added 65 ppm of CYA with the gallon of liquid and 4 pounds of dry CYA you added. Do NOT add that 6 pounds they want you to add, something is wrong with their testing if it’s showing no CYA still. Another 6 pounds (which is another 55 ppm) and you’d have too much CYA and would need to do a partial drain and refill!

We want everyone to have a good quality kit like the Taylor K-2006C or the TFTeskKits TF-100 kit. Get one and do your own testing you can rely on, and we can help you get your water in tip-top shape.