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Thread: Combined chlorine and ammonia problem

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    Combined chlorine and ammonia problem

    We recently opened our pool and are having a problem with combined chlorine and ammonia. I have a 33,000 gal vinyl in ground pool (fc 0.5, cc 5, pH 7.2, TA 140, CH 160, CYA 0). I can't get the FC level to budge above 0.5-1.0 and the combined chlorine is reading 5+. Based on discussions on this site I decided to check the ammonia level which reads about 6.0-8.0 (I admit to letting the pool go over the winter and opening it late). To get rid of ammonia it has been suggested to shock to 10x the ammonia reading, so in my case 60-80 ppm. In a 33,000 gal that's a lot of chlorine!

    A coworker told me that non-chlorine shock (specifically potassium peroxymonosulfate) can be used to destroy ammonia. Is this true? If so, are there any drawbacks? It might be preferable because my understanding is that it will start destroying some ammonia without having to shock to the 60-80 ppm breakpoint and it would be safe to swim shortly after application (which is important since company is coming for the holiday weekend.

    I apologize if this doesn't make any sense as I'm still trying to get my head around the chemistry. Any help and input is appreciated.

    Thanks,
    Sean M.
    12K IG gunite, Pentair Intelliflo pump and 1 hp Pentair booster pump, Posi-Clear Sta-rite cartridge filter, IntelliChlor SWG and EasyTouch system.

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    Re: Combined chlorine and ammonia problem

    Do you have any organic material in your pool? I'm not talking algae, but foreign material such as leaves.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Mod Squad Bama Rambler's Avatar
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    Re: Combined chlorine and ammonia problem

    The breakpoint myth is just that, a myth. While it takes that amount of chlorine to break it down you don't have to try and add it all at once.

    Without any CYA in there you need to add enough chlorine to get to 10 ppm FC and test and add what's needed to get back to 10 as often as every hour. The only reason to wait an hour is to allow the water to mix. You will need to have lots of chlorine on hand to make this go as quickly as possible.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Combined chlorine and ammonia problem

    Agreed, it's going to suck chlorine for a while! You might be surprised how much chlorine you are adding each hour.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: Combined chlorine and ammonia problem

    Quote Originally Posted by RobbieH
    Do you have any organic material in your pool? I'm not talking algae, but foreign material such as leaves.
    No, the pool is clean and the water looks pretty clear although you can tell it's a little milky when looking at the deep end.

    Thanks,
    Sean M.
    12K IG gunite, Pentair Intelliflo pump and 1 hp Pentair booster pump, Posi-Clear Sta-rite cartridge filter, IntelliChlor SWG and EasyTouch system.

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    Re: Combined chlorine and ammonia problem

    Sounds like you just need to follow the shock process as outlined here:
    pool-school/shocking_your_pool

    Don't let a friend or a pool store talk you into a bag of shock as a total solution.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
    If TFP has helped you, please click to SUPPORT TFP!

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    JasonLion's Avatar
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    Re: Combined chlorine and ammonia problem

    Non-chlorine shock will work just fine, but it will end up costing more than the chlorine required to do the same job will cost. The amount of chlorine required is 8 to 10 times the ammonia level, but remember that you can also lose chlorine to sunlight, so you might need more than that if you do it during the day.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Combined chlorine and ammonia problem

    What happens if I'm not able to retreat every hour? Last night I put in enough bleach to raise FC to 10 ppm (~ 6 gals of 6% bleach, I think). An hour later I retested the FC and it was still at 0.5 - 1 (pump running the entire time) so I put in more bleach then had to go to bed. Working during the week I won't be about to re-treat every hour for hours at a time so are my 2 doses an evening helping or just making things worse?
    12K IG gunite, Pentair Intelliflo pump and 1 hp Pentair booster pump, Posi-Clear Sta-rite cartridge filter, IntelliChlor SWG and EasyTouch system.

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    Mod Squad Bama Rambler's Avatar
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    Re: Combined chlorine and ammonia problem

    When converting ammonia nothing really bad happens if you don't keep at it. It's not like algae, that starts back growing as soon as the level drops, it just takes longer to get it all oxidized but the end result is the same. Do it as often as you can. We all understand the need to have a real life to go along with the pool life.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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