What am I doing wrong? Chlorine isn't going up.

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A

aumfc

Well-known member
Apr 16, 2023
59
Pelham, AL
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
Hey Everyone,

The pool was finished about 2 years ago. I keep the pumps going year round, so no closing or opening. Just adding liquid chlorine over the winter.

Last year right before it was warm enough to swim, chlorine levels looked good once I got more salt in the water. This year that hasn't happened.

1. What am I missing that I should be doing to get the chlorine up? I'm assuming I need to get it higher than 0.5 or 1. The SWG is set to 100% and the pump is going 24 hours a day.

A couple of less important questions:

2. We've had a lot of rain but my overflow drain isn't draining as fast as last year. It's barely a trickle and taking days to go down 1/8 of an inch. What can I do about this?

3. My Polaris EPIC 8640 vacuum seems to be flipping a lot and not sticking to the walls as well even though the basket is empty. Is it just getting old or is there something I can do about it?

Here are my logs from the Pool Math app. I missed logging a lot of the chlorine / pH tests and the additions related to those two, but hopefully it helps to see the numbers.

  • New pool opened in May 2023
  • 5/22/23 – 5.5 FC, 0 CC, 7.8 pH, 120 TA, 200 CH, 40 CYA, 3200 Salt
  • 7/2/23 - 3.0 FC, 0 CC, 8.2 pH, 100 TA, 275 CH, 20 CYA, 2400 Salt
    • Added 120lbs Salt
  • 3/5/24 – 3.0 FC, 7.8 pH
  • 3/23/24 – 0 FC, 0 CC, 8.2 pH, 90 TA, 250 CH, 20 CYA, 1600 Salt
    • Added 320lbs Salt
  • 3/24/24 – 3200 Salt
  • 3/29/24 – 4.0 FC, 8.2 pH
  • 4/14/24 - added 7 lbs dry stabilizer
  • 4/16/24 - 3 FC, 7.6 pH
  • 4/17/24 - 50 CYA
  • 4/18/24 - added 3.5 lbs dry stabilizer
  • 4/19/24 - 55 FYA
  • 6/8/24 - 2 FC, 7.5 pH
  • 7/17/24 – 1.5 FC, 0 CC, 7.3 pH, 110 TA, 375 CH, 60 CYA, 2800 Salt
  • 9/10/24 – 10 FC, 8 pH
  • 9/11/24 - 7.5 FC, 7.8 pH
  • 12/8/24 - 4.5 FC, 7.8 pH
  • 1/18/25 - 0.5 FC, 7.8 pH
  • 2/2/25 - 0.5 FC, 7.8 pH
  • 3/2/25 - 0.5 FC, 8.4 pH
  • 3/4/25 - 4 FC, 7.8 pH
  • 3/12/25 - 1 FC, 7.8 pH
  • 3/22/25 - 0.5 FC, 7.8 pH
  • 4/4/25 - 0.5 FC, 7.8 pH
  • 4/18/25 - 0 FC, 8.2 pH, 74 F
  • 4/19/25 - cleaned the filters
  • 4/20/25 - 1800 Salt
    • Added 240 lbs Salt
  • 4/21/25 - 2800 Salt
    • Added 80 lbs Salt
  • 4/22/25 - 2.0 FC, 7.8 pH, 3300 Salt
  • 4/26/26 - 0.5 FC, 0.5 CC, 8.2 pH, 60 TA, 450 CH, 30 CYA, 3000 Salt
 
a,

It appears to me that you are trying to keep your FC way too low and you now have algae, even if you can't see it yet..

Too things that effect your FC level...

1. Being burned off by the sun, because your CYA is too low

or

2. Being consumed by algae

In your case one of those two things is true...

The first thing that I would do is perform an Overnight Chlorine Loss Test to see if you have algae.. To do this test you need to get your FC up to about 6 ppm by adding liquid chlorine about half an hour before you start the OCLT..

Overnight Chlorine Loss Test

I would also check my CYA level..

I try to keep my FC at my Target or higher... I never ever try to keep my FC between the Minimum and my Target.

Thanks,

Jim R.
 
I mean, I'm not trying to keep it low. It being low is the problem I'm trying to fix. I don't know why it's not staying up like it did last year at this time.

I know the CYA needs to come up but I don't think that's the problem just now because the FC is low in the evening and in the morning, even though everything is running overnight. So, there must be some algae in the system.

I'll run the overnight to be sure, then raise my CYA a little. It may be less than 30 that's just the lowest I can test. Then SLAM.

Thanks.
 
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Reactions: Jimrahbe and PoolStored
Hey Everyone,

Here are my logs since starting the SLAM yesterday morning.

How does it look? Anything else I need to be doing or am I on track?

4/28 8:49a - added 3g Chlorine, 1 g Muriatic Acid, set SWG to 0%
4/28 10:59a - 13.5 FC
4/28 1:11p - 8.0 FC
-- Added 2g Chlorine
4/28 4:10p - 13.5 FC
4/28 6:43p - 11.0 FC

4/29 7:13a - 9.5 FC
-- Added 1.25g Chlorine
4/29 9:27a 13.0 FC
4/29 11:34a 11.5 FC
4/29 1:41p 9.5 FC
-- Added 1.5g Chlorine
4/29 3:57p 9.5 FC
-- Added .75g Chlorine
4/29 7:50p 10.0 FC

Thanks.
 
Keep on testing and adding chlorine. The algae is consuming it and you replenish it.

With CYA 30 your target FC is 12. Test 15 minutes after you add chlorine and confirm you got it up to 12 or more.
 
Tested this morning.

3/30/25 5:59a - 10.5 FC, 0.5 CC

Since there was no chlorine loss, water is clear, and CC is 0.5, that means it's done, right?

Thanks.
 
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