Salt cell, an atypical technical question.

[epc002a]

I have a Hayward T9 salt cell that's at the end of it's useful life, it has been confirmed as failed, requiring replacement. Fortunately it's still under Hayward warranty and a claim has been filed with Hayward. Unfortunately Hayward is unable to provide any replacement cells for at least 3 months (supply chain issues...). In the meantime I've resorted to liquid chlorine.
My question is this: Would temporarily wiring up the salt cell to an external 24VDC power supply be able to squeeze a little more chlorine-producing life out of the cell, or would that risk adverse side water chemistry, for example metals electro-migration from having a dissipated ruthenium oxide coating? The Hayward PL-PS4 controller will currently not turn on power to the salt cell as it (incorrectly) measures the salt level (conductivity) as too low, even though it's 3400ppm. In a simple test, using an external 24VDC PSU will cause the cell to draw around 2.5 amps and produce chlorine.

 

[proavia]

Use of mismatch parts is not recommended. Chances are that the external power supply is not even rated for pool use. Use of non pool rated electrical items is dangerous. Don't place convenience above safety.

You will be using less liquid chlorine during winter as compared summer.

 

[Tcadwall0]

Not sure of the validity or applicability with your PL system... Hopefully others can chime in... I did see the following on a QA "In The Swim" blog:

I have a Hayward prologic system and T-9 cell 4 years old. My actual salt levels in the pool are 4100ppm. Verified by strips and store. But my display says low salt and shut the chlorinator off even with the high salt levels. I cleaned cell and still getting the same reading. Is there a way to calibrate the prologic system? Or is it a bad cell?

• 
  Davy Merino on August 26, 2020 at 11:19 am said:
  Hi Ivan, If you enter the Diagnostic menu, then press the right arrow & it will go through a set the numbers and you’ll see salt level dropping, when it gets to 4100 ppm, turn the breaker off to the Prologic, then back on again quick.

 

[ajw22]

I don't know how you will know how much chlorine is being generated to rely on the cell.

In addition connecting up an external power supply bypasses the flow switch which is an essential safety device.

I doubt the juice is worth the squeeze.

@JamesW

 

[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]

You can change the cell type to T-5 or T-3 to make it work longer.

 

[epc002a]

Use of mismatch parts is not recommended. Chances are that the external power supply is not even rated for pool use. Use of non pool rated electrical items is dangerous. Don't place convenience above safety.

You will be using less liquid chlorine during winter as compared summer.

The temp setup I'd use will be designed to be very safe, with multiple fail-safes., and used only until Hayward can honor the cell warranty.
"winter" is a relative term, here in S FL
Heater extends swim season, meaning chlorine demand will not decline very much.

 

[epc002a]

I don't know how you will know how much chlorine is being generated to rely on the cell.

In addition connecting up an external power supply bypasses the flow switch which is an essential safety device.

I doubt the juice is worth the squeeze.

@JamesW

I use a Taylor K-2006 to determine actual chlorine level, pretty much the same process to iteratively determine chlorine % setting on the controller throughout the year.
If I use an external PSU, I'd gate it via the flow switch(with optocoupler), plus I'd have it on a timer to get a target chlorine level.

 

[epc002a]

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.

In diag mode I can temporarily restart the salt gen. If I quickly do a save after a restart, the salt gen will start, but the ppm it measures quickly declines(as do amps), starting around 1000ppm and quickly dropping, when it gets to about 400 the salt gen turns off. Doesn't take long.

It's a T9 Hayward cell (original, not a "W").
I always use a Taylor K-1766, it confirms 3400ppm is the actual salt level.
(aquarite strips and pool store(which I'd never solely trust) also confirm around 3400)
As noted, the cell has been tested on a Hayward tester, it is confirmed as failed.

The T9 cell is almost 3 years old, and has been unequivocally determined to be failed, it's at the end of it's useful life. A T3 or T5 cell would be impractical for this size pool, and would have significantly shorter lifetimes for the chlorine demand. A T15 is a better match for this size pool, but if Hayward can actually honor their warranty with a replacement T9, I'll be using that for another few years, after which I'll switch to a T15.

serials 1st seven:
Pl-Ps-4: 3L18127 rev 4.46
T9: 3E18211

My main question here is for someone with metallurgical experience, whether powering a salt cell that has a dissipated ruthenium oxide coating will cause some undesirable metals electro-migration or not.

 

[JamesW]

when it gets to about 400 the salt gen turns off.

If it is going down to 400 ppm, then the cell has probably completely failed and using an external power supply would be pointless.

A T3 or T5 cell would be impractical for this size pool, and would have significantly shorter lifetimes for the chlorine demand.

I did not mean to change the actual cell to a T-3 or T-5.

I meant that you could change the cell type in the configuration menu to see if that would make it work longer.

That will work if the salinity reading is going down to 2,000, but not if it’s going all the way down to 400 ppm.

Try changing the cell type to T-3 and then see what the readings are.

 

[epc002a]

If it is going down to 400 ppm, then the cell has probably completely failed and using an external power supply would be pointless.

I did not mean to change the actual cell to a T-3 or T-5.

I meant that you could change the cell type in the configuration menu to see if that would make it work longer.

That will work if the salinity reading is going down to 2,000, but not if it’s going all the way down to 400 ppm.

Try changing the cell type to T-3 and then see what the readings are.

View attachment 380654

My apologies, I should've realized you meant to change cell type in the controller, not change the physical cell. I've now set it to a T3 cell type and did a diag reset, saving quickly at 3100ppm salt level. The cell starts at 3100ppm and 2.7 amps, and surprisingly, after an hour it only went down very little, to 3000ppm and 2.59 amps. So changing cell type appears to a quick and easy workaround vs using an external PSU (which as noted also pulls around 2.5 amps). Thank You!

Although I still am wondering if running like this with depleted ruthenium oxide will cause some undesirable metals electro-migration.

 

[JamesW]

The main concern would be if the plates were disintegrating and shedding titanium flakes.

You can look into the cell to see if you can see the edges of the plates, but they are difficult to see.

 

[epc002a]

The main concern would be if the plates were disintegrating and shedding titanium flakes.

You can look into the cell to see if you can see the edges of the plates, but they are difficult to see.

Several months ago I did the usual acid clean, at that time I was noticing reduced chlorine output, having to raise the controller CL % level. I assumed that was because it was summer and hot (actually the cell was failing). At that time I also saw some small black flakes in the used acid solution, I collected a few to examine closer, they would smear into a towel, not like a metal. I now think that may've been degrading ruthenium.

 

[JamesW]

If you look in the end, you see plastic screens, but the plates are behind the screens.



Below is my cell where you can see the plates.

The plates are titanium with a ruthenium oxide coating.

It is currently not working, but I am not sure what is wrong with it.

Hayward Aquarite SWG - Further Reading

www.troublefreepool.com

Here are the dimensions of the Hayward plates:

T-15 has 13 Titanium Plates, 150 x 63mm. Produces 1.47 lbs/day.

T-9 has 13 Titanium Plates, 101 x 63mm. Produces 0.98 lbs/day.

T-5 has 7 Titanium plate, 150 x 63mm. Produces 0.735 lbs/day.

T-3 has 7 Titanium Plates, 101 x 63mm. Produces 0.53 lbs/day.