Trouble determining accurate salt level for Pentair IC-40

finethreads

Bronze Supporter
Feb 14, 2014
44
Santa Rosa Beach, FL
Good morning, I have a one year old pool with all Pentair equipment. Due to cold water I shut down the IC-40 over the winter and just added liquid chlorine as needed.

Now as I start it up I am experiencing pretty wide variations in salt water ppm depending on how I test. My current water temperature is 69 degrees. Prior to testing I cleaned the salt cell per Pentair's instructions.

My Taylor kit is currently showing 5800 ppm. The IC-40 is showing 4350 ppm, but a couple of days ago was showing in the 3800's. I dropped a water sample off at the local pool store and their test showed 3300 ppm. I'm losing confidence in my ability to determine the actual salt ppm. Should I just go with the results of the Taylor Test kit? Thanks!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,889
Tucson, AZ
Good morning, I have a one year old pool with all Pentair equipment. Due to cold water I shut down the IC-40 over the winter and just added liquid chlorine as needed.

Now as I start it up I am experiencing pretty wide variations in salt water ppm depending on how I test. My current water temperature is 69 degrees. Prior to testing I cleaned the salt cell per Pentair's instructions.

My Taylor kit is currently showing 5800 ppm. The IC-40 is showing 4350 ppm, but a couple of days ago was showing in the 3800's. I dropped a water sample off at the local pool store and their test showed 3300 ppm. I'm losing confidence in my ability to determine the actual salt ppm. Should I just go with the results of the Taylor Test kit? Thanks!
I would retest with the Taylor kit but it will be the most accurate as it directly measures chloride (Cl-) concentration. All other tests (electrical testing or strips) use a proxy to measure salt content, either electrical resistance or fluid permeation or buoyancy. The Taylor test kit is a true chemical determination of the chloride concentration. If your water is truly at 5800ppm, then it is likely from the bleach and acid you were adding to the water as well as any fill water if it's from a municipal source (municipal supplies can have 50-200ppm chloride content).

Your IC-40 varies because it measures the conductivity only once per 12 hour period and usually right at startup when the water is coldest. There is not "instant read" on the IC units unless you cycle the cell power. But here's the key - you need to satisfy the salt cell. So I would only lower your waters chloride content by doing a partial drain and refill until the salt cell is happy (say 3600ppm) even if your true chloride content is higher.

Also, don't sweat it too much; the SWGs are designed to operate over a very wide range of salt concentration and you will not damage a cell by being high or too low. If you truly go low, the cell protects itself and shuts off. If you go too high, the cell actually continues to generate chlorine because the rate limiting step on the high end is not concentration of chloride but available electrical power and the power supply is clamped at a certain voltage and current.

Hope that helps.

Matt

- - - Updated - - -

Oh, and forget pool store testing. As you will learn form reading around here, we do not put much faith in pool stores to properly and/or accurately test your water.
 

pooldv

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Aug 10, 2012
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FL panhandle
Mine doesn't seem to really start acting right until the water is consistently above 70. I have had my salt well above 4500ppm due to adding salt when the water was cold and getting low salt error lights. Good news is that the IC40 doesn't give a high salt error until 4500 ppm. Other good news is it keeps making chlorine even above 4500 ppm. I didn't have to add salt for over a year. :)

As Matt says, if the SWG is happy and making chlorine then everybody is happy. Just be careful about adding salt when you get a low salt error in the IC40 when the water is below 70ish.
 

finethreads

Bronze Supporter
Feb 14, 2014
44
Santa Rosa Beach, FL
Okay, I am now at temperatures consistently above 70 degrees. My IC-40 is still showing erratic salt levels. Over the last two weeks I have had readings ranging from 2500 to 4100. The temperature of the pool is currently at 73 degrees. Here are my salt readings as of this morning:

SWG - 3350
Taylor Kit - 5200

I'm getting ready to leave for the summer (4 months) and am trying to anticipate a potential pool problems in advance. Thanks!
 

finethreads

Bronze Supporter
Feb 14, 2014
44
Santa Rosa Beach, FL
Yes, I inspected and cleaned it about 2 months ago. Upon inspection the cell looked perfectly clean with no calcium buildup. The muriatic acid wash (per pentair instructions) resulted in no noticeable bubbling. Should I take another look at it?
 

JamesW

TFP Expert
Mar 2, 2011
13,370
Possibly a failed or failing temperature sensor. What is the cell mfg date and version number (on bottom of cell)?

Also, check chlorinator diagnostics in your automation.
 

pooldv

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Yes, I inspected and cleaned it about 2 months ago. Upon inspection the cell looked perfectly clean with no calcium buildup. The muriatic acid wash (per pentair instructions) resulted in no noticeable bubbling. Should I take another look at it?
no, it should be fine then.
 

JamesW

TFP Expert
Mar 2, 2011
13,370
The IntelliChlor can be a little erratic with salt readings. As long as the diagnostics show ok, it's probably ok.
 

pooldv

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Agreed, I am a little leery of the salt reporting from my SWG also. I usually add a bag and wait a couple of days to see before adding another.
 

JoyfulNoise

TFP Expert
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May 23, 2015
14,889
Tucson, AZ
The IntelliChlor can be a little erratic with salt readings. As long as the diagnostics show ok, it's probably ok.
Agreed, I am a little leery of the salt reporting from my SWG also. I usually add a bag and wait a couple of days to see before adding another.
I don't know guys, I hate to argue about it but my IC40 salt readings are never "erratic" in any way. They go up pretty smoothly from when the cold water cutoff deactivates and all the way up to standard swim season pool temps then back down again when it gets cold. Plus, I'm not sure how one can see them being "erratic" in any way as the salt readout is only refreshed once every 12 hours, i.e., it's not an instant read salinity measurement. We've discussed in a previous thread about it potentially not having very good temperature compensation but that would just manifest as a salinity output that varies with water temp.

I think the OP should simply call Pentair support and see if they can diagnose it.
 

pooldv

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Good points Matt. My feelings and comments about my SWG, temp, and salt are very unscientific and reactionary. I have added too much salt (above 4500 ppm once) a couple of times because it said low salt and the temp was well above the 50-whatever cutoff and probably in the upper 60s. Now, my water is in the mid 70s and says low salt and I am leery and skeptical about adding more. So, I add a bag, wait 2 or 3 days and add another.

All of that aside, I am very happy with the 4 year performance of my SWG during the swim season. And I just shut it off below 70 and use bleach.

Thanks for the sanity check.
 

finethreads

Bronze Supporter
Feb 14, 2014
44
Santa Rosa Beach, FL
Thanks again for all the helpful advice. I did call Pentair a couple of months ago. The tech explained that it was most likely the cold water (60's at the time) that was causing the varied readings. I will call them tomorrow and let you know the results.
 

finethreads

Bronze Supporter
Feb 14, 2014
44
Santa Rosa Beach, FL
Just got off the phone with Pentair. Very helpful as usual. The tech advised me to wait until pool water reached warmer levels, after which he said the IC40 salt readings should stabilize and be more accurate. I am at 73 degrees. Taylor salt test readings show 5100 ppm. The IC40 shows 3400. I will wait until I get up to 77 and see where the readings are. The tech said to call back if the readings are still way off at warmer temperatures.
 

bdavis466

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Aug 4, 2014
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Your results are too far from eachother even factoring in water temp. I see about a 600ppm difference between the Taylor test and cell when the water is cold.

Are you certain you are doing the test correctly?
 

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