Hayward Tcell940 - Low Salt

[g0yanx77]

Hello fellow pool enthusiasts! Long story short...our 20x40 pool was installed a few months ago. An AquaRite 900 and Tcell940 were installed at that time, and the system always reads low salt when the correct cell type (T-15) is configured. My installer changed the cell type to T-9, and stated that the change was needed due to our automatic pool cover. Something's not right.

I bought a Taylor K-1766 test kit, and the measured salinity was 3600ppm today. I also cleaned the cell today...it was terribly scaled, but was clean when I was done. Instant salinity when configured with a T-15 cell type is ~2200. Serial number on the Tcell940 is 4E21, so I believe that indicates it was manufactured this year?

I'd really appreciate any help I can get. The system does run if T-9 is selected as the cell type, but chlorine levels are always very low even with the pump running 24x7.

 

[JamesW]

For AquaRite, move the switch from auto to off and check all of the readings.

Move the switch back to auto and recheck the readings.

Move the switch to off for a minute and then back to auto and recheck the readings.

Switching the unit off and then back on makes the unit reverse polarity.

Report all readings.

What are the first seven characters of the cell and box serial numbers?

What is the actual salinity and how are you measuring it?

What is the T-cell size?

Is the T-cell size set correctly in settings?

To get the performance percentage of the cell in each polarity, divide the instant salinity reading in each polarity by the actual salinity reading.

For example, if the instant reading is 3,300 ppm and the actual salinity reading is 3,300 ppm, then the salt cell is working at 100%.

However, if the actual salinity was 3,800 ppm, then the performance percentage is 86.8%.

Anything over 75% is acceptable.

At75%, or lower, in either polarity, it's time to consider replacing the cell.

The instant salinity in both polarities should be about the same (+/- about 200 ppm).

You need to be really sure about the actual salinity reading.

You need to use a K-1766 salt test kit or a calibrated meter.

K-1766 Taylor Salt Test

Note that ProLogic, AquaLogic and AquaPlus use the Hayward T Cell.

However, the procedure to get the diagnostic readings is different.

Here is the procedure for ProLogic, AquaLogic and AquaPlus:

Go to the diagnostic screen, note the readings and then press the + button to reverse the polarity.

When the new numbers appear, see what they are.

Then, press + again and note the new readings.

 

[JamesW]

What are all of the chemistry readings?

You need to check the salinity two new good ways to make sure that you know exactly what it is with high certainty.

Does the cell say 940 on the label?

 

[g0yanx77]

Thanks, James!

Cell says 940 on the label. Serial is 4E21125. I will get the serial off of the controller tomorrow and update this post. I will also get readings after resetting, per your instructions above.

Salinity was measured with K-1766 today - 18 drops = ~3600ppm. Cell efficiency quick math shows 2200/3600 = 61%.

As for chemistry...appears I need to invest in a decent Taylor setup. All I have at the moment is AquaCheck strips, except for the K-1766 for sodium chloride.

pH as measured by strip was sky high, and I've been trying to bring that down a bit by gradually adding muriatic acid.

 

[JamesW]

A lot of scale can cause the cell to underperform.

Never rely on a single salinity test, especially when there is some reason to believe that it might be inaccurate.

You need to verify the actual salinity two new and different ways.

Get a good test kit and get your CSI under control as soon as possible.

 

[g0yanx77]

Appreciate all of the help!

Diagnostics readings from this morning:

Tcell940 serial = 4E21125-201648
AquaRite 940 serial = 4A21125-103132

Controller set to OFF position
2600
87
33.6
0.00
95P
-0
AL-0
r 1.59
t-15

Controller switched to AUTO from Off:
2600
87
27.8
5.71
95P
-2200
AL-0
r 1.59
t-15

Controller moved to Off for one minute, then back to AUTO:
2600
87
27.6
5.76
95P
-2200
AL-0
r 1.59
t-15

Question - is it possible that high pH/Alkalinity can scale over a salt cell extremely quickly (as in 1-2 months)? I cleaned it yesterday, and the acid solution bubbled for a good 30 minutes. Worthwhile to clean it again?

 

[JamesW]

Question - is it possible that high pH/Alkalinity can scale over a salt cell extremely quickly (as in 1-2 months)?

It can scale in days with a high CSI.

Keep the CSI between -0.3 and 0.0.

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If the cell is clean, the actual salinity is probably about 2,200.

A lot of scale can cause the cell to underperform.

Never rely on a single salinity test, especially when there is some reason to believe that it might be inaccurate.

You need to verify the actual salinity two new and different ways.

Get a good test kit and get your CSI under control as soon as possible.

 

[g0yanx77]

Thanks again, James. I'd like another salinity test, since the Taylor K-1766 shows 3600 and the Hayward controller says 2200. What would you recommend for a new salinity test?

I did order a Taylor K2006 complete test kit, so I'll work on the CSI.

 

[JamesW]

What are the chemistry readings now?

Try a different K-1766 and a calibrated meter.