High ORP levels with low Chlorine

[UrielM]

Hi
I am new owner of Plaster pool with SWG .
My problem is that while my ORP levels are high (>850mV) , my chlorine levels are low (TC and FC) , and since maximal system threshold is 850mV my only way to generate chlorine is by running the turbo mode which generates chlorine regardless of the ORP sensor.
I must say that my pool gets direct sunlight most of the day , and chlorine drops rapidly. till yesterday I never used CYA ( since I was told by the support guy that unnecessary for SWG pools)
I contacted the SWG support and ORP sensor was replaced this week , but no changes were seen.
Pool water is crystal clear and nice.
I was wondering, why I have such high ORP while Chlorine dissolves completely?
What can I do to reduce ORP levels without affecting other properties, so system will be able to operate within the proper range ?
Thanks

 

[ajw22]

Welcome to TFP.

ORP chlorine control systems do not work well. ORP is a poor proxy for chlorine levels.

There is no reason for ORP control when using a SWG. A pool with SWG needs weekly chlorine testing and occasional SWG % adjustments.

ORP information question

Disclaimer: I do not use ORP to control anything. It's strictly for my information. So, I bought this Wi-Fi Ph/ORP tester from aliexpress mostly because I'm interested in anything related to home automation. And later replaced probes with atlas scientific (consumer) ones. It seems to show Ph...

www.troublefreepool.com

The ORP probe is sensitive to all kids of redox chemical reactions as well as pH and sunlight conditions. The one thing you would want an ORP probe to be sensitive to is the hypochlorous acid (HOCl) concentration as that is the primary oxidizer and sanitizer in water. However, cyanuric acid is a chlorine buffer meaning it captures most of the chlorine and holds it in reserve. That results in very low levels of HOCl which is fine for sanitation and oxidation but is often too low for an ORP probe to be useful. So it’s basically a signal to noise problem - lots of useless noise with very very small signal embedded into it.

Outdoor pools absolutely need CYA and an SWG tends to need higher levels than a manually chlorinated pool. If you didn’t use CYA with your SWG, then you’d have to run it at 100% output all the time which would reduce its lifespan greatly.

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[UrielM]

Thanks for your answer
So I am wondering, should I disable the ORP close - loop and generate chlorine on regular basis?,

 

[ajw22]

So I am wondering, should I disable the ORP close - loop and generate chlorine on regular basis?,

Yes, set your SWG to generate the daily FC your pool needs.

Best to add stabilizer/CYA to protect the chlorine from loss due to the sun UV.

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

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