Chlorine explosion - Help

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C

Ck91

Member
Jul 16, 2021
18
Memphis, TN
Been about 2 weeks since i tested my pool here are my stats below with some additional details. Has maybe rained a few times at most over this span.

FC - 13
CC - 0
PH > 8 (2 drops acid demand lowered it to 7.6)
TA - 80
CH - 140
Cya <30, black dot never went away
Salt - 4200

Im starting to think something just went wrong with the chlorinator as my levels have been acceptable for months (3-5 FC) and I moved it from 100% to 50% output. I just dropped it to 25% for my next test to see what happens.

Any guess why chlorine exploded? Any other help to get this all balanced without affecting everything across the board would be great. TIA
 
Lower UV loss as the summer winds down. You do not show what model SWCG you have so cannot see what FC you are creating each day.
Get your CYA to 40 ppm. Do not mess with pH until the FC is below 10 ppm (pH test is invalid with FC above 10 ppm).
 
With a swg the CYA level should really be between 60-80 ppm. A low CYA can result in large FC swings due to UV exposure changes.
 
Ck91 said:
Breeze 540
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At 25%, running 24 hours per day, will add 2 ppm FC to your water. That should be sufficient at this time of year with a proper CYA. As Mark said, best is to raise the CYA up to normal SWCG levels.
 
Bringing this back up again after testing today. I got my CYA to about 50, #'s are generally the same, however my FC has gone up even more to about 15.5. Should i keep chasing cya or just shut off the SWG (at 25% currrently) at this point for a few days and see what happens?
 
Ck91 said:
Bringing this back up again after testing today. I got my CYA to about 50, #'s are generally the same, however my FC has gone up even more to about 15.5. Should i keep chasing cya or just shut off the SWG (at 25% currrently) at this point for a few days and see what happens?
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I'd shut it off and test the FC every day until it gets down into the 6-8ppm range. Chlorine demand definitely goes down as both the temperature, sun angle, and shade changes.

I plugged my SWCG into a WiFi plug so I could adjust it remotely after I test without having to go back out -- I leave the output dial at 100% and just vary the number of hours it runs with the app. In the peak of summer when I had the solar cover off during the day, I ran it for 7 hours a day to match the demand, I recently had to bump it down from 3 to 2 hours a day (solar cover is on during the day most days) because the FC level was rising beyond what I wanted otherwise.

You can do the same by adjusting the %age; if 25% is the lowest you may need to have it off some days this time of year until the water gets too cold to generate at all.
 
It's a challenge this time of year. I kept having to lower my SWG down until the output was at 20%. That was a good setting until I starting using my solar cover again. The FC jumped from 5 to 10 ppm in a week. So now I've got to decrease it again. I will probably start at 15%. That'll change again in a few weeks when I shut down the heat pump and the water starts cooling.
 

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Thanks for the info so far. After 2 days with the SWG off i have my FC down to 4. At this point do i just leave it off for the foreseeable future, do i put it back on to the lowest setting (25%) and keep monitoring? To me it seems putting it back on i will eventually have to shut it off again but I am a newbie :)
 
Ck91 said:
To me it seems putting it back on i will eventually have to shut it off again but I am a newbie :)
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Ok great !!! Let’s get ahead of this for next year. See what’s happening right now ? The seasonal demand wanes a bit and you overproduce and make ‘too much’ chlorine. A GREAT problem to have as its safe up to SLAM level (40% of your CYA). But it does shorten the SWG lifespan to run it (don’t worry we are talking hours from 10k hours), so you want to lower the output or runtime anytime you notice you are overproducing.

I’m a bit north of you but I got 4-6 weeks from each adjustment. Frequent testing will let you see it coming slowly. After you gain 1 or 2 PPM, lower the % or pump runtime to get back to just enough. Test frequently as you learn your system after adjusting it. You might do too much or too little and need a 2nd adjustment in a day or two.

Now. Next year you will do the exact *opposite*. You’ll start early with next to no UV demand and low production % / run time. It will quickly ramp up and you’ll be looking out for underproducing each time the demand goes up. So a few weeks later you’ll bump it up. And up and up and up again and then it’s mid season and it starts to go down little by little again.

Now is a GREAT time to learn or hone your skills and you’ll be a pro for next year.
 
Newdude said:
Ok great !!! Let’s get ahead of this for next year. See what’s happening right now ? The seasonal demand wanes a bit and you overproduce and make ‘too much’ chlorine. A GREAT problem to have as its safe up to SLAM level (40% of your CYA). But it does shorten the SWG lifespan to run it (don’t worry we are talking hours from 10k hours), so you want to lower the output or runtime anytime you notice you are overproducing.

I’m a bit north of you but I got 4-6 weeks from each adjustment. Frequent testing will let you see it coming slowly. After you gain 1 or 2 PPM, lower the % or pump runtime to get back to just enough. Test frequently as you learn your system after adjusting it. You might do too much or too little and need a 2nd adjustment in a day or two.

Now. Next year you will do the exact *opposite*. You’ll start early with next to no UV demand and low production % / run time. It will quickly ramp up and you’ll be looking out for underproducing each time the demand goes up. So a few weeks later you’ll bump it up. And up and up and up again and then it’s mid season and it starts to go down little by little again.

Now is a GREAT time to learn or hone your skills and you’ll be a pro for next year.
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Makes sense and definitely now is the time to really start learning. For these adjustments is it better to lower pump time (I currently run it 24/7) vs having the SWG off completely or does not matter?
 
It's all the same. Turn it off until the FC is in range (preferably a tad above range to allow wiggle room for **cough cough laziness cough** events to happen). Or lower the pump runtime. Or lower the SWG output %, which is nothing but its own runtime during the times the pump is running,
 
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