I have a new ic40 installed july of this year. The low salt light is on and the salt level says 2600. I also have the taylor salt test that I bought at the same time as the tf-100, it shows 3600. I searched on here but I think the concensus was the newer ones cant be calibrated?
I looked inside and it's clean, I don't want to add more salt unless needed. Any input as to what I should do?

Did it work correctly at some point (I assume it did)?

Has the water changed much since the unit last ran?

It was working, and it still is, just has the low salt warning. I just thought the taylor test was more accurate than the swg sensor.

There is no way to calibrate the newer units. They will keep working untill the salt level drops to 2300 ppm. Pentair had no recomendation other than add more salt, or lower the pool temp to 81 deg get a more accurate reading. Evidentally at higher water temps the salt sensor reads lower than actual, at colder temps it reads higher. They also said to power down and restart the unit. I did that and added another bag of salt so my level will be approx 3800 ppm now, up from the 3600 ppm it was. I don't want the salt level any higher so I'm going to ignore the low salt light if this does'nt fix it.

Seems you have hit the easy points. I seem to recall my IC40 giving a strange reading when I had my 3050 running at a very low speed (maybe even 750 or whatever the minimum is). You might try spinning it up a bit and see if that makes a diff. Otherwise I'm pretty clueless as to other issues.

The min rpm I have used is 1650, now with the solar or the waterfall the rpms are 2000 or 2200.

As of this morning all lights are green. The swg shows 2800 ppm, my Taylor test shows 3800 ppm. Sure would be nice if they had a more accurate sensor, then I could keep a lower salt level. The calibration would be nice but I suspect they removed it because they had uninformed people screwing things up.

Did you try the calibration steps I explained in this thread? I have an IC40 and it works on mine:
http://www.troublefreepool.com/ic-40-with-the-red-low-salt-light-always-on-t32180.html

I didn't, what year was your unit installed? I asked the pentair guy on the phone if the new units can be calibrated and his answer was "no". He said the older models could be. Not sure if there is a difference in the calibration sequence since mine is controlled by the easy touch.

Version 2.01, MFG Date of: 11/06/09 and installed a little over a year ago.

Where did you find the version & mfg date?

Underneath the cell...

A couple days ago the ic40 was reading low salt again 2700 ppm, taylor test showed 3800 ppm, next day ic40 shows 3900 ppm.... what?, one day later it was back to 2650 ppm, now this morning it's showing 3650ppm. Pool temp has ranged from 82 / 85 deg. Seems kind of erratic as far as the salt sensor goes. Still producing chlorine good though.

I have an Aquarite so this may not apply, but I see something similar if the generator doesn't run for a while. The salt concentration right on the front of the unit is really a 24-hour average, and for some reason when the generator is on but not running, it will assume that the salt is 0 during that time. On my unit you can get an "instant salt" reading which is always in the ballpark, even if the average is off. I just encountered this last week when a rat ate my flow sensor cord - the unit was on but not generating, with a no-flow message. When I fixed the cord, the normal salt reading was 1100, but the instant reading was 3300. It stabilized over the next day. Sorry for the rambling; I hope that helps.

Interesting, thank you.

After a few phone calls they have a service call scheduled. As of today the swg shows 2600ppm, the taylor test 3600ppm. Per the pentair people there is no way to calibrate the new units. Hope the new unit works correctly.

1) When using SWG, Keep you eye on your other chemicals, PH, TA, CH, Temp, Etc.
2) Keep note on your SI Index.

Based on the water passing in the cell will determined the voltage that is pulled off those blades.
The cell use that voltage based on the water temp to find out the salt readings. (This is why they tell you to clean the cell too)
If the voltage pull is wrong then the readings will also be wrong.

Its not that the cell is showing readings jumping around. Its your water chem thats jumping around due to the water temp changing or something else.

Always look at the SI!! What is your SI?

I have a felling if they replace the cell it will not solve your issue

The swg had stopped producing since the salt level was "very low" according to it but taylor still showed 3600 ppm. Before it stopped I did an acid wash with 3-1 muratic acid although there was almost no scale. It did bubble for approx 1 min and then I let it sit for another 15 min. Just did a full water balance test 11-6-11.

Fc 10
cc0
tc 10
ph 7.6
ta 80
ch 300
salt 3600
cya 55
temp 70

This puts the csi at -.33 unless I made an error.

I turned off the swg and the cl level was at 2ppm, I added cl manually, a little more since the water is too cold to swim. I think the balance is nearly perfect. If the salt sensor can't deal with this, they need to redesign it.

How's that warranty call moving along? This is definitely atypical; you're correct that it should work just fine in these circumstances.

They are finally coming out in the next few days.
It did take a liitle more effort on my part, I called approx 5 times, and faxed info 3 times. The first responce was "add more salt", the next, after nearly the same questions by another rep was "send proof of purchase", warranty card was faxed. That wasn't good enough so I found my contract and faxed that, no responce, faxed again. Finally after not being able to get the same person, another helped and got the appointment set up for this week, not sure when yet. Hopefully this one reads the salt level correctly.

I can tell you with my experience with Pentair, they are slow to respond. I emailed them through their site and didn't get a response for about a week. They have come through both times I needed warranty repair completed - just slow. Fortunately, for me the one time they were very slow, it wasn't a real important problem.