Intellichem ORP setting making chlorine super high

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Olga

Olga

0
Mar 24, 2016
30
Phoenix
The company that built our pool seems lost on how to set up the Pentair Intellichem system. The pH keeps shooting up and every day the Pentair alarms go off and the techs stop by and dump lots of acid into the pool. Think Groundhog Day. They dumped so much yesterday that we went well below 7 pH. So I decided I ought to try to figure it out, starting by testing the water myself. The readings from the test kit were so out of wack that I took a water sample to the pool store for testing. Indeed the Chlorine is super high at 10. TA low at 70, CH low at 150, and Phosphates high at 200.

They had the ORP setting at the recommended level, but at that level the SWG was cranking out more chlorine continuously. The ORP set level is now lowered to 590 and the chlorine generator is idle. My question is, what in the water could be fooling the ORP sensor, when set at the recommended level, to think that there's not enough chlorine and demanding more chlorine?
 
CYA is the biggest offender of interference for ORP sensors. What is your level? There are several other things in the water that can also throw off the reading for ORP.

It sounds like your pH sensor is fouled or may need to be recalibrated. Your TA is fine where it is, not need to touch it.

The IntelliChem is a great device when it works as intended, but it requires frequent recalibration, and routine manual testing (more so than conventional pools) to make certain that it is actually doing what it is supposed to be doing.
 
jblizzle said:
:wave: Welcome to TFP!!!

What kind of test kit are you using? We do not put much faith in pool store testing around here. ;)
Click to expand...

Thanks!

Taylor K-2005. I tested with the kit first, but the values were so far off I wanted confirmation. The pool company, as it turned out, repeated the same process, looked like they were using the same test kit, and got the same result.
 
bdavis466 said:
CYA is the biggest offender of interference for ORP sensors. What is your level? There are several other things in the water that can also throw off the reading for ORP.

It sounds like your pH sensor is fouled or may need to be recalibrated. Your TA is fine where it is, not need to touch it.

The IntelliChem is a great device when it works as intended, but it requires frequent recalibration, and routine manual testing (more so than conventional pools) to make certain that it is actually doing what it is supposed to be doing.
Click to expand...

Ah, the CYA, that could be it. It was 99. I was surprised it would be so high in a new pool. I thought that accumulated over a long time using chlorine tabs. Is it possible the pool company added it and put in too much? Then the only fix is to drain some water, ---expletive here---.

Here's a great article on CYA I just dug up after your tip that it may be the problem.
http://www.ppoa.org/pdfs/PrP_Cyanurics - Benefactor or Bomb.pdf
If all the chlorine is bound up with CYA, the 680 target ORP level would be nearly impossible to reach, so the system keeps cranking out chlorine trying to get there, which explains the crazy high chlorine. That pdf has a nice chart for ORP and CYA interaction. In fact they state exactly
"If ORP won’t rise when you pump the sanitizer into the pool,these systems won’t meet set-point and wont turn off. Any claimto the contrary is simply false. (Try it in a bucket someday..!) Allcontrollers will function OK at low levels of CYA (if you lie to thecircuit by up-calibrating to compensate for the lost ORP) andnone of them works at high CYA. Period."

I did test run two tests, probe test and meter test, and both passed. I'll look at the manual to see what I can do about calibration. I don't want to monkey with it too much yet because the pool experts who built it are still in charge setting it up.
 
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A CYA of 99 is code word for "so high we have no idea". The test only goes up to about 100ppm, unless you follow a dilution method.

You are very close to having one of the recommended test kits, the K-2006. Luckily you only have to add the VERY important FAS-DPD Chlorine Test and you will have a much better ability to test the FC and CC levels.
 
How long did you use them? Your cya is very high for using pucks for such a short while.

For ORP to be relatively accurate with little interference, a cya of 30-40 is about as high as you can go. Trouble with this is that you'll go through a bunch of chlorine (lost to uv light) and will be taxing the SWG to keep up. Since you have the intellichem already, I'd suggest abandoning the ORP and running the SWG on a time based run cycle and using the intellichem for pH monitoring and acid injection only.

You'll also need to lower your cya to a measurable level... 80 would be great.
 
After several partial drainings and water replacements we got the CYA down to just under 30, the recommended level shown on the Intellichem box cover. The Intellichem seems to be operating just fine so far, keeping chlorine and ORP in line. Thank you for pointing me in the direction of too high CYA, which was indeed the issue.
 

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