Can't keep Chlorine in the pool

Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I've been struggling keeping chlorine in the pool, help would be appreciated. I added 4 gallons of 10% bleach in last night and today all of it seems to be gone. I've done this several times. I have checked this with TF100, also checked with a strip and it has the same results.

I should say all of these tests are from last season. I just noticed the Taylor total chlorine test slowly changed from 0.5 to 3 as it sat on the table. Maybe my old reagents are the problem?

Also about 3 week ago my CYA level went to zero all the sudden.

27,500 gallon pool
Hayward 40k SWG
Vinyl lining
Pool stays covered, have a motorized pool cover
Salt 3300
Temp 93°
FC 0.5
CC 1
TC 1.5
CH 300ppm
TA 120
PH 7.2
CYA 50 (adding a bit more to bring this up to 70)
Pool clear
 
Last edited:

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,190
NY
Prove it first :

Confirm that You Have an Ammonia Problem in Your Pool Water​

  1. Your CYA will be 0
  2. Add chlorine for 10 ppm and test your free chlorine after 30-minutes. You likely have ammonia in your water if you lost 80%+ of FC in 30 minutes
  3. Your CC tests > 0.5
  4. Optional: An ammonia test indicates the presence of ammonia
 

Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Prove it first :

Confirm that You Have an Ammonia Problem in Your Pool Water​

  1. Your CYA will be 0
  2. Add chlorine for 10 ppm and test your free chlorine after 30-minutes. You likely have ammonia in your water if you lost 80%+ of FC in 30 minutes
  3. Your CC tests > 0.5
  4. Optional: An ammonia test indicates the presence of ammonia
Well my cya is no longer at zero. If it itsn t Amonia then what could it be? Phosphates?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,190
NY
But it did disappear so there is that. Not sure how adding more CYA affects the results but before you did, you had the 2 big markers for ammonia. Run the 10ppm / wait 30 min test. if you lose a considerable amount of FC in 30 mins than there is your answer.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,622
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
If you had ammonia I suspect adding CYA would've made it worse, the CYA would've fallen, and the pH might have crashed. I would recommend staying aggressive with the chlorine, but not waiting 30 minutes if the FC is falling quickly. Add chlorine right away.

1. Confirm CYA. If it's zero, add chlorine to an FC of 10 and verify every 10 minutes. If the CYA is clearly holding at 40 or 50, then take the FC to SLAM level (i.e. 16 or 20).
2. For the first couple FC tests, check again in about 1o-15 minutes. Only when you are sure the FC is holding, then begin to spread out your testing intervals. Whatever is eating your chlorine, you don't want to let it continue to do so.
 
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Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
If you had ammonia I suspect adding CYA would've made it worse, the CYA would've fallen, and the pH might have crashed. I would recommend staying aggressive with the chlorine, but not waiting 30 minutes if the FC is falling quickly. Add chlorine right away.

1. Confirm CYA. If it's zero, add chlorine to an FC of 10 and verify every 10 minutes. If the CYA is clearly holding at 40 or 50, then take the FC to SLAM level (i.e. 16 or 20).
2. For the first couple FC tests, check again in about 1o-15 minutes. Only when you are sure the FC is holding, then begin to spread out your testing intervals. Whatever is eating your chlorine, you don't want to let it continue to do so.
I took my pool water to Leslie's pool, their automated machine says cya is at 78 and FC it 0.2

So getting up to slam levels is FC 30. 9 gallons of bleach. 😮
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,622
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
I took my pool water to Leslie's pool, their automated machine says cya is at 78 and FC it 0.2

So getting up to slam levels is FC 30. 9 gallons of bleach.
I wouldn't do that just yet. As you have already heard from us a TFP many times, we do not rely on pool store testing. They often get those wrong, especially the CYA. Trust your onw TF-100 CYA test. That's the number to base your SLAM FC level on, not Leslie's.
 
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Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I wouldn't do that just yet. As you have already heard from us a TFP many times, we do not rely on pool store testing. They often get those wrong, especially the CYA. Trust your onw TF-100 CYA test. That's the number to base your SLAM FC level on, not Leslie's.
Okay I tested myself. I get cya of 70. So 28 FC, 8 gallons of bleach. Slightly better. Here we go!
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,622
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
full
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,355
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Vigorously brush the pool with pump running. But typically chlorine disperses pretty well as it is hydrophillic.
 

Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Vigorously brush the pool with pump running. But typically chlorine disperses pretty well as it is hydrophillic.
Okay so I figured out what's going on after I goofed up some more.

I left the pool alone for 5 hours and checked the levels, back to FC 5.5. I picked up 16 gallons of chlorine which is way overkill but adding 8 + 7 gallons got me to 5.5 and I said well I'm going to go for it and see if I can break this Chlorine wall. I poured all 16 gallons at once. I checked the pool and FC is 62. 😮 So that's a lot.

What happened?

I check the chlorine levels by the skimmer side of the deep end and I pour chlorine by the return jet deep end. I read that after 1 hour chlorine levels are dispersed around the pool. Not true for my pool, maybe it's because I have a deep end. So I scrubbed the walls and ran the pool cleaner now the pool is thoroughly mixed and wow, I have a lot of FC now. It's going to rain all next week so no pool time anyways. SLAM level for me is 30 so I'm above slam levels and will keep it slammed for days at this FC level and kill everything! I might run out of r-871 reagent though.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,355
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Other concern is effecting the liner color/pattern. Very high FC can fade it.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
3,122
Spring Valley, NY
It doesn't really work that way. Any FC over the slam ratio is pure waste. Here at TFP we teach a process and doesn't mean more is better.
By the way when you added CYA was it granular or liquid and did you add enough to create 70? To save on reagent use 5ml of pool water and each droplet =1. Not the most accurate but for the beginning of slam it'll be close enough.
 
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Sonton2003

Member
Jun 8, 2020
20
Cincinnati, OH
Pool Size
27500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
It doesn't really work that way. Any FC over the slam ratio is pure waste. Here at TFP we teach a process and doesn't mean more is better.
By the way when you added CYA was it granular or liquid and did you add enough to create 70? To save on reagent use 5ml of pool water and each droplet =1. Not the most accurate but for the beginning of slam it'll be close enough.
I added granular CYA.

I've been letting the FC come down on it's own checking it 3x a day.

FC has gone from 65 (8/14/21) >62>57>53>51 (8/18/21) as of this morning. (overnight loss of 2)
CC is 1 or less. I can't get that accurate since I'm conserving reagent using 5mm of pool water instead of 10mm.
The pool is crystal clear, wow i've never seen it this clear. I'll keep letting it come down to 30 and do an accurate overnight loss test.
Long term goal is to keep the pool FC at 6 at this CYA level.

Thanks for all the help but it's important to note for other people that bleach won't just mix on it's own in a few hours. I needed the pool robot to really get it mixed right, it might be because I have a deep pool.
 
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