Higher water temp = Higher salt reading? Intellichlor IC40

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3

3to1Glide

0
Jun 30, 2015
5
Chandler, AZ
First Post - Love troublefreepool! I am on pool number 2 using your methods with fantastic results.

For reference, the pool in question is in Chandler, AZ.
12,000 gal pebble tec play pool. SWG (Intellichlor IC40 ver 2.02 mfg date 10/25/10).

Troublefree says do the folllowing for SWGs, so when I refilled the pool at our new house in April, that's exactly what I did...(#s are what they are now)

--------------------------------
FC 4-6 ppm (6)
PH 7.5-7.8 (7.6)
TA 60-80 (70)
CH

  • 250-350 for plaster (310 pebble)

CYA 70-80 (60 - I need to add a bit more CYA...diluted water 2x during troubleshooting)
Salt 200-400 ppm ABOVE recommended optimum level (3400 - was 3600, but diluted water 2x during troiubleshooting)
Borates 30-50 ppm (optional) (yes - 40)
---------------------------

As the air temps and water temps have risen in AZ over the past 6 weeks I have been trying to troubleshoot why the "High Salt" light keeps coming on our Intellichlor IC40. The SWG is otherwise working perfectly. The pool temp is currently 92 deg. Air temps have been 105-115 for a few weeks now.


My question is pretty straightforward. Will the Intellichlor SWG read a higher salt level with warmer pool temperatures? If so, is there a good rule of thumb or chart I can reference?

I called Pentair and his answer was YES. The rep says the unit measures conductivity and that the IC40 is calibrated for 3400ppm at 77 deg water temp. Their rule of thumb is for every degree above 77, the unit 'sees' about 100 ppm higher salt level. So at 92 deg water temp, the unit thinks it's at 4900ppm salt, even though it's not actually that high.

He said as long as the unit is producing chlorine, the high salt light can be ignored and should go away when water temps cool.


Do the experts here agree, or have different advise/rules of thumb? I trust this site most when it comes to my pool!


For reference, this is what I've done while trying to wrap my head around this issue...

Over the last 6 weeks, I have diluted my water twice (about 6-8" each time). I have also on 2 other occasions ran the fresh water hose in the skimmer bucket with pump running (but swg off) for 30 min or so. All 4 times, the high salt light stopped flashing and behaved normally for anywhere from 2 days to almost 2 weeks. The Pentair rep said the light went off due to lower temp water being added, not necessarily from a lower salt ppm due to dilution.

My trouble shooting thought process involved...
1) maybe my math was wrong (I doubt it) and I did add to much salt when pool was refilled.
2) maybe it had something to do with faster evaporation or fill water that was salinated (tap water here has about 500ppm salt)
3) maybe the salt level sensor on the IC40 has gone or is going bad
4) maybe SWG is starting to fail completely (all other signs point to no, though)

Right now I'm at a crossroads - let light flash away or use my home warranty to have someone come out. Knowing that the unit is 5 years old, it would be nice to have it replaced. On the other hand, maybe nothing is wrong...

Any help would be greatly appreciated. Thank you in advance!
 
What test did you measure the salinity with?

A flashing high salinity light is just a warning and if the salinity is in range then you can ignore the warning. The IC40 does not have temperature compensation so it will read a higher salinity level when the water temp rises.
 
The 3400ppm was from the reader at Leslie's. The machine looks like a small funnel attached to an ammeter-like head that reads salt ppm as water pours through. They claim it's as accurate as it gets. I discount just about everything that store tells me, but that one piece of equipment seems to be legit. Should I be wary of it's results?

If the IC40 doesn't have a temp compensation, then all this makes a lot of sense, as the high salt light problem presented itself as the pool temperature rose. The one thing that bugs me is that after diluting the water, pool temps were just as warm within 24-48 hrs, but the high salt light stayed off for almost 2 weeks.

The only other clue is that the light seems to start flashing when either the pump is turned back on in the evening after running all day (occasionally I'll do this to run the water feature with guests over), or after a bunch of kids are in the water doing a lot of splashing and churning up the water more than normal.

I read that the various SWG's can read salt ppm and/or conductivity and/or TDS levels. It's just unclear to me exactly how the IC40 determines salt ppm to be within range.

I'm wondering aloud if having both dissolved salt and borates in the pool raises the base TDS level and could exacerbate the temp rise issue more on pool party days.

It seems that if it's a straight lack of water temp compensation at the unit, then problem solved.

It also seems it could have something to do with TDS levels based on how the problem presents.

And of course, it could be something wrong with the unit/sensor itself.
 
As long as the unit is producing chlorine, it's ok. There's nothing you can do about the temperature drift.

Does the IC40 sit out in the sun all day? If so, it can get warm and show a conductivity higher than the pool water temperature. If you can, try shading the unit with something reactive to reduce external heating.

I would not activate the home warranty idea. All that will do us result in a service call from some random pool company that the warranty company chooses. They will not just replace the unit but request that the service tech try to "fix" it. That just sounds like a problem waiting to happen.


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The good news is that the IC40 will continue to produce salt even when giving high salt warning. Even if you actually have high salt. I did my own personal tfp test just for the good of all of us and my IC40 produced chlorine with salt above 5000 ppm. Wasn't that nice of me! :-D
 
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The IC40 electrodes measure water conductivity, that's it. Therefore it's basically a TDS meter. Anything that conducts will cause the TDS to increase. Typically the manufacturers add in a little fudge factor so that the displayed "salt" value is slightly less than the actual TDS value. There's only so much you can do from an engineering standpoint as there is no electrical probe capable of simply measuring chloride. The manufacturers do their best to get the units to work over the widest possible ranges.

If you want peace of mind, but a Taylor K-1766 salt test and you'll know your salt level to within +/-200ppm. Then you can adjust your water salinity based on an actual chloride value. Then just ignore the high-salt light.


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Also, the IC40 does not show a continuos value. It measures the TDS at startup and then once every 12hours of operation time. The value on the display is the last recorded TDS value.


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It depends on how the borates were added. If you used the Borax/Muriatic acid method, then the neutralization of the pH rise from borax results, ultimately, in the creation of sodium chloride thus increasing the TDS by adding both boric acid and excess salt. If straight boric acid was used, then the TDS increase is lower since you don't create any excess sodium chloride.

In the end, I think the TDS rise from boric acid is only about 100ppm or so (i don't know the exact calculation off hand) but it is much smaller than your salt level contribution to TDS (~ 3500ppm).


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