Hayward T-15 on its way out….

[Lake Placid]

Edit: 2016 Vintage Hayward T-15 at a customers throwing low salt error in spite of actual salinity testing 3300 ppm.

Cell diagnostic data:

2600 2600
84 84
27.0 25.8
4.39 5.66
65P 64P
-1800 -2600
AL-0
R1.59

Obviously the cell is on the way out but it’s still producing. I’ve been resetting the instant salinity to allow the cell to run for a while before it re-averages the wrong salinity and throws a low salt error. Memory serves @ogdento had a thread (that I can’t find for the life of me) where he set the cell type as a different unit to buy some time. I was thinking I may try the same to limp the cell through the end of the season for the customer (he already knows it’s on the way out). Is it as simple as telling the controller a t-9 is installed for instance, and would this help given the current readings above? All input is helpful. Thanks

 

[proavia]

I think Mark @mas985 has a post recently outlining what he did to extend the life of his cell.
EDIT: Here it is

Failing T-15 SWG Cell Experiment

I am currently on my 3rd T-15 SWG cell for an 18 year old pool. The 1st cell lasted about 9 years and the 2nd about 4 years and just passed year 4 on the 3rd cell. I thought it might be useful to document this cell's behavior as it is going through the last stages of useful life. As time goes...

www.troublefreepool.com

Basically change the controller from a T-15 cell to a T-9 cell and check the salinity.
As I recall, you can also go to a smaller cell size when needed as the cell continues to degrade.
Customer needs to plan on replacing the cell - but this may buy them some time.

 

[Lake Placid]

I think Mark @mas985 has a post recently outlining what he did to extend the life of his cell.
EDIT: Here it is

Failing T-15 SWG Cell Experiment

I am currently on my 3rd T-15 SWG cell for an 18 year old pool. The 1st cell lasted about 9 years and the 2nd about 4 years and just passed year 4 on the 3rd cell. I thought it might be useful to document this cell's behavior as it is going through the last stages of useful life. As time goes...

www.troublefreepool.com

Basically change the controller from a T-15 cell to a T-9 cell and check the salinity.
As I recall, you can also go to a smaller cell size when needed as the cell continues to degrade.
Customer needs to plan on replacing the cell - but this may buy them some time.

That’s it! Thank you for finding it. My googlefoo was failing. @mas985 - Mark any additional recommendations to stretch this thing for the customer?

 

[mas985]

The only thing that the PO might experience is the cell will tend to accumulate scale faster because side reactions seem to increase at end of life. I found that I needed more frequent acid soaks to bring the cell "back to life".

 

[mas985]

Forgot to mention that the production rate decreases as well so higher percentage settings and perhaps longer run time will probably be necessary.

 

[Lake Placid]

The only thing that the PO might experience is the cell will tend to accumulate scale faster because side reactions seem to increase at end of life. I found that I needed more frequent acid soaks to bring the cell "back to life".

Forgot to mention that the production rate decreases as well so higher percentage settings and perhaps longer run time will probably be necessary.

Thanks. I’m only looking to stretch this thing about 10 weeks until closing, so I’m not over concerned about scaling as it’s been scale free for the 18 months I’ve had the account. Do you think in that timeframe I need to check it weekly for scaling?

 

[mas985]

Keep an eye on Amps and FC levels. A dip could indicate scale and/or corrosion but it is not always directly visible. After an acid soak, I noticed a distinct jump in current and FC levels.

 

[JamesW]

Do you think in that timeframe I need to check it weekly for scaling?

Depends on the CSI.

 

[mas985]

During the experiments I ran on my two failing cells, CSI was well below -0.3 and scaling still occurred. It was most likely due to the side reactions of the cell with the catalyst degraded. But I would still try to keep the CSI on the lower end of the range since it could have been much worse.

Plus oxidation of the plates reduced conductivity and productivity even further that only an acid soak would rectify.

 

[Lake Placid]

Got it. Generally I run CSI slightly negative but not as low as -0.3. Generally it floats around -.15 or slightly upwards. I’ll work to keep it lower as closing approaches.

 

[PoolStored]

During the experiments I ran on my two failing cells, CSI was well below -0.3 and scaling still occurred. It was most likely due to the side reactions of the cell with the catalyst degraded. But I would still try to keep the CSI on the lower end of the range since it could have been much worse.

Plus oxidation of the plates reduced conductivity and productivity even further that only an acid soak would rectify.

Have you ever tried borates, to reduce pH in the cell, avoiding scaling? That is the only thing that I can wrap my mind around why you have to run your CSI below -.2 or -.3 (I've seen conflicting posts).

 

[mas985]

I think the main reason for different experiences with CSI vs scale may be due to different ages of the cell. I have been running my new cell for about a month now and have not seen any scale at all. The mean CSI has been -0.28 during this time. My plan is to keep better track of when scale shows up so I can correlate that with CL production rates and CSI.

The scaling that I saw got worse the closer to cell failure. This is possibly due to the catalyst wearing away and the cell experiencing more side reactions. Plus, as I showed in the other thread, the plates get really rough, like 100 grit sand paper, and scale seems to stick more to the surface and accumulate.

I am sure that borates would help some but I am not sure it would be that significant given the state of the failing cell.

 

[mas985]

One other factor I forgot to mention is CH level. Historically, the CH level in my pool has very pretty high. Median levels have been over 500 ppm. Last year in December I replaced the pool water because CH was over 700 ppm. The city has recently turned off some wells so when I filled the pool, it was with much lower CH fill water and now the pool has a CH level of around 225 ppm. After the water change, I noticed less scaling on the failing cell but it was still scaling and it still needed fairly frequent cleanings the closer to final failure.

So while CSI is a factor in scaling, I think that absolute level of CH also has an impact when the cell is failing. Again, perhaps due to side reactions.