Chlorine Demand

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
Denniswiseman
Pool Industry Leader
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My Pool: 10k inground fibreglass, Telescopic Cover, Hayward Powerline pump, Quality filter with glass media, 27kw output heat pump, K-2006C test kit
Location: United Kingdom

Re: Chlorine Demand

Postby Denniswiseman » Sun 07 Nov, 2021 03:09

With a CYA about 40 you need a slam FC level of 16
Turn off the SWCG and just use liquid chlorine
Continue untill the CC is 0.5 or less


blackadder
Pool Enthusiast
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My Pool: Inground concrete pool with pebblecrete finish. 10m x 5m and approx 50,000 litres.
Sand filter with salt water chlorinator.

Re: Chlorine Demand

Postby blackadder » Mon 08 Nov, 2021 01:30

I have had a suggestion that my pool may be suffering from mustard algae, and I would appreciate your thoughts on the likelihood of this before heading off on a tangent.
Teapot1
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My Pool: 12000 gallons vinyl liner,

Re: Chlorine Demand

Postby Teapot1 » Tue 09 Nov, 2021 10:45

I very much doubt it, this is often the last words of bafflement used in the pool world to separate those from yet more money. In almost every case I have attended mustard algae has turned out to be pollen or dust, not saying it can't happen but its really rare.

Not being there to test for myself but chemicals we add interact and mess with some tests. You won't for example have water with 0 TA, it just tests that way due to a chemical interfering the the reagent. With high levels of chlorine and peroxymonopersulfate (MPS), you can oxidise CYA out of the water. Also there is a bacteria that can eat the CYA and leave ammonia in its place. Ammonia has a massive chlorine demand and you end up feeding lots in to get the ammonia out but that may not be it in your case as you have a good level of chlorine. Remember when I said the MPS shows as combined chlorine? That feels like what you are experiencing so unless you get any other issues just keep going and wait for an overnight chlorine loss of 1ppm or better then you have Slammed enough.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.

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