Chlorine demand in winter

Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
Hi again, guys!!

So, we have a 15k gallon quartz plaster pool in Oklahoma. We’re keeping our pool open all winter...we have an attached spa we use frequently. I don’t think our salt water generator has ran in 1.5-2 months since our water temps have been so much colder since then.

That being said, I’ve been checking my chlorine levels several times per week with a Taylor test kit, and our chlorine levels have been maintaining around 5-6 ppm all winter so far. I have not added a drop of liquid bleach to our pool yet, based upon these results. Our pool looks fantastic, too. 🤷🏼‍♀️ Is this normal? I’m afraid to go ahead and add the liquid chlorine anyway, as I feel like our levels are about right. Our CYA is currently about 60. Thoughts? TIA!!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
34,741
Laughlin, NV
Hard to believe there has been NO chlorine loss over that time period. You are adding some chlorine somehow.

Do you have your SWCG disabled or is it just off due to 'Cold Water'? If still Enabled, the SWCG is adding chlorine during your SPA use as the water is warmer.
 

Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
Hard to believe there has been NO chlorine loss over that time period. You are adding some chlorine somehow.

Do you have your SWCG disabled or is it just off due to 'Cold Water'? If still Enabled, the SWCG is adding chlorine during your SPA use as the water is warmer.
No, we didn’t turn the SWG off. It just says “cold water.” I didn’t even think of that scenario. That’s a good point. 🤔 Maybe we’re using the spa just enough to keep a small amount of chlorine being generated via the SWG. That sounds like a good little side effect of using the spa every now and again. Do you think that’s ok? It won’t hurt the SWG, will it?

Honestly, I keep the pool completely vacuumed out and skimmed almost every day, too, which probably doesn’t allow for hardly any chlorine demand, either.
 
Last edited:

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
34,498
Sebring, Florida
Unless your pool is completely indoors, you are using chlorine. Please read "The "ABC's of Pool Water Chemistry" up in Pool School......chlorine is a consumable item.....both from UV light from the sun and organics in your pool water.

Your testing methods are inadequate or in error. What test kit are you using?
 

JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,192
Prosper, TX (DFW)
Wake - I'm a little warmer than you, but I will say that mine has not used much chlorine at all this winter too. I stocked up on 4 gallons of liquid chlorine and had some pucks left over in a floater. My CYA was a bit low so I put 3 pucks in a floater in November about the same time the SWCG turned off, which are still in the floater and kept my FC elevated.

The only other chlorine addition I did was I dumped 1/4 gallon of 10% liquid chlorine left over from last winter the week before Christmas since I was planning on heating the pool and having kids swim. That got me up to 13.0 on the FC and I have remained at 10+ for the last 2 weeks. We started the heater Christmas day, but turned it off a few hours later and had to cancel our swim plans for that week. Both pool and spa are set to 5% output, so even if it generated some during the spa usage, it was very minimal.

I'm totally fine with not having to add, but like you, surprised a bit at how little I have used. I assume the cloudy winter days have really helped as well.
 
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Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
Usually in SPA mode, the SWG is reduced to 5%...what is yours set to during SPA mode?
I have an IntelliCenter. It just shows (in the app) 15% of chlorine generation (that was what I had it set to at the end of summer/beginning of fall while the weather was cooling off and chlorine consumption was falling off). I haven’t changed it since then. I think Mknauss was right...when the water became warm enough (in spa mode), it kicked the salt generator back on out of cold water mode and generated a couple hours worth of chlorine...probably just enough to keep me from adding it yet. That’s the only thing I can figure. That being said, I checked my chlorine level again the other day and it was around 3-4 ppm. Since my CYA is around 60, I poured some bleach in to get my chlorine level right around 5 (midrange). This is the first time I’ve had to manually add bleach all season.
 

Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
Unless your pool is completely indoors, you are using chlorine. Please read "The "ABC's of Pool Water Chemistry" up in Pool School......chlorine is a consumable item.....both from UV light from the sun and organics in your pool water.

Your testing methods are inadequate or in error. What test kit are you using?
I think Mknauss was correct when he said our salt generator is likely producing just enough chlorine while we’ve been using the spa. We’ve used it several times this winter. And the salt generator must be kicking on while the water is warmer running through there. I’ve read the ABCs of pool chemistry several times. I’m pretty well-versed in that. Plus, we’ve had a pretty cloudy and cold winter so far here in Oklahoma, so I’m sure the chlorine demand is low. I also keep the pool very clean. I vacuum and net it out several times a week. And make sure the skimmer baskets stay cleaned out. I know it’s impossible to keep all “organics” out, but I must say I do a pretty good job! 🤣

I use a Taylor “Complete Poolcare DPD Test Kit.”
 

Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
Wake - I'm a little warmer than you, but I will say that mine has not used much chlorine at all this winter too. I stocked up on 4 gallons of liquid chlorine and had some pucks left over in a floater. My CYA was a bit low so I put 3 pucks in a floater in November about the same time the SWCG turned off, which are still in the floater and kept my FC elevated.

The only other chlorine addition I did was I dumped 1/4 gallon of 10% liquid chlorine left over from last winter the week before Christmas since I was planning on heating the pool and having kids swim. That got me up to 13.0 on the FC and I have remained at 10+ for the last 2 weeks. We started the heater Christmas day, but turned it off a few hours later and had to cancel our swim plans for that week. Both pool and spa are set to 5% output, so even if it generated some during the spa usage, it was very minimal.

I'm totally fine with not having to add, but like you, surprised a bit at how little I have used. I assume the cloudy winter days have really helped as well.
Yes!! I’m surprised, too. I do keep the pool cleaned out really well. And we’ve had a lot of cold and cloudy days. So, I guess that’s why. Our demand is just really low. I FINALLY the other day put some bleach in the pool. Our chlorine got down to 3-4. With a CYA of around 60, I decided to add some bleach to keep the chlorine in midrange, around 5 ppm. At any rate, I will say our pool looks clear and great! I’m happy for much, much lower chemical usage over these colder months!
 

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JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,192
Prosper, TX (DFW)
It would be wise to consider getting a proper FC/CC test kit. The FAS-DPD. What you have can only test FC in the single digits and by color matching, which is not accurate.
A perfect example of this is my chlorine test from a second ago. While the picture seems a little more dramatic than what my eyes see in real life, there is no way I could tell my real FC reading from this since orange is not on the chart. I have to use the FAS-DPD to know that my FC is actually 11.0.

IMG_7078.jpg
 
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Wake9909

Silver Supporter
Mar 28, 2020
32
Broken Arrow, OK
I see. My test reads within the color ranges, as I
Never let my free chlorine get over 7.5(ish). I use a test kit that reads up to 10 ppm, though. That being said, I went ahead and bought the FAS-DPD test that Mknauss suggested. 👍🏻
 

setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
3,804
Stuart/FL
Pool Size
12800
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-30 Plus
Wake,

You'll need the test Marty recommended if you ever need to do a SLAM anyway. It's also very accurate and easy to read.

Chris
 
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