Ph plus turned pool green

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Ph plus turned pool green

Postby Richardb » Sat 18 Jun, 2022 11:58

I never use chemicals in my pool. Simply keep the surfaces clean, use 1 or 2 slow release chlorine tablets in the skimmers. Perfect clean water you could drink.
But just to ensure all was well I checked the ph and it was below 6.8. So I added some ph plus, about 250g. Just to ensure there would be no skin irritation issues for visitors.
Instantly, green clouds formed in the water as the ph was added. The green cloud spread throughout the pool.
SO I checked the ph and still below 6.8. Must be due to low ph? I added 5kg of ph plus. Result -even greener. Baffled.
Reluctant to add more ph chemical, I added Chlorine shock about 1kg . The green turned to a brown soup.
Running the pump 24/24 for now with fingers crossed. I wish I had never used any chemicals at all.

Any ideas what has happened?

Pool is 5m x 10m = about 75m3.

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Re: Ph plus turned pool green

Postby Denniswiseman » Mon 20 Jun, 2022 06:50

The fact you only use stablised chlorine tabs indicate you probably have excessive CYA a chemical that you apparently don't use

Excessive CYA renders your chlorine ineffective and you have to use more to get the same sanitation
For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm
To reduce your CYA you have to do a partial drain and refill
Continuous use of Trichlor/Dichlor will raise your CYA which means you have to raise your chlorine level as well

Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit

Use these common products to balance your pool
Liquid chlorine (sodium hypochlorite or plain bleach) Liquid chlorine only adds salt
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Soda ash will raise pH and TA
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Re: Ph plus turned pool green

Postby Teapot1 » Mon 20 Jun, 2022 11:57

And the colour especially green to brown sounds like metals in the water. At a low pH the metals stay in solution but raising the pH and adding an oxidising agent drops the metsls out of solution.
Adding chlorine tablets IS using chemicals and more than you realise. Little blue flecks in the tablets are copper sulphate. They also contain CYA as Dennis has said but also aluminium in the form of flocculent.
The need to add pH+ is a guide to something not right so what are your other water test parameters?
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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