Squeeze last bit of life out of cell?

[Saturn94]

I suspect that yours is probably 8.0 amps regardless of what the manual says.

Today the panel had a flashing Low Salt alarm with Instant Salt reading 2600. So I changed the cell setting from T15 to T9.

Set on T9 the diagnostics read 25.7 volts, 6.17 amps, instant salt 4300. Average Salt is reading 3500, likely because I didn’t reset it after changing the cell type setting. There are no alarms so far. Water temp is 83.

Is it likely to give a High Salt alarm once Average Salt goes up? Or is the High Salt alarm only triggered when amps exceed the high amp limit?

 

[JamesW]

I think that it's just 8.0 amps.

 

[Saturn94]

I think that it's just 8.0 amps.

Thanks.

I just noticed in the Diagnostic Manual regarding the Low Salt alarm, it says when flashing, which will occur at 2500-2600 ppm salt, chlorine is still being produced. If the alarm light is on steady, which will occur at 2300 ppm, then chlorine production is stopped.

So I guess I could opt to ignore the Low Salt flashing alarm? Any issue with this?

Thanks again.

 

[JamesW]

So I guess I could opt to ignore the Low Salt flashing alarm? Any issue with this?

You can do that. I would probably just leave it on T-9.

 

[Saturn94]

You can do that. I would probably just leave it on T-9.

I’ll leave it on T9 and see how it goes.

BTW, chlorine production has continued to be fine. As a matter of fact, I had to turn down the % as FC has been rising recently, likely due to less sun/lower angle of sun on the pool this time of year.

 

[Saturn94]

You can do that. I would probably just leave it on T-9.

Quick question.....as long as volts and amps are reading normal, is there any reason to adjust the actual salt level in the pool if the actual salt level is higher than recommended?

 

[JamesW]

Quick question.....as long as volts and amps are reading normal, is there any reason to adjust the actual salt level in the pool if the actual salt level is higher than recommended?

No reason to adjust the salinity as long as the volts and amps are good.

Watch the salinity vs. actual to detect when the cell is beginning a rapid decline.

Once the cell is in the final stage, the salinity reading on the box will get lower and lower while the actual stays the same.

 

[mas985]

Is it likely to give a High Salt alarm once Average Salt goes up? Or is the High Salt alarm only triggered when amps exceed the high amp limit?

High salt alarms only occur when you exceed the amp limit.

So I guess I could opt to ignore the Low Salt flashing alarm? Any issue with this?

That is what I did with my last two cells. I only have a choice of the T-15 and the T-5. Even though the cells degraded quite a bit, the T-5 setting generates alarms and shuts the cell down (> 5A) so I stuck with the T-15 setting. Anyway, changing the cell type really doesn't do much other than change the readout for salt and the amp limits. As the cell degrades, the cell efficiency will also decline so less CL is produced even with sufficient amps and the amount of CL generation has degraded so much, that you may not be able to generate enough CL within your run period.

 

[JamesW]

so less CL is produced even with sufficient amps

I would think that the amps would be proportional to the amount of chlorine generated unless the amps are doing something else?

 

[Saturn94]

No reason to adjust the salinity as long as the volts and amps are good.

Watch the salinity vs. actual to detect when the cell is beginning a rapid decline.

Once the cell is in the final stage, the salinity reading on the box will get lower and lower while the actual stays the same.

High salt alarms only occur when you exceed the amp limit.

That is what I did with my last two cells. I only have a choice of the T-15 and the T-5. Even though the cells degraded quite a bit, the T-5 setting generates alarms and shuts the cell down (> 5A) so I stuck with the T-15 setting. Anyway, changing the cell type really doesn't do much other than change the readout for salt and the amp limits. As the cell degrades, the cell efficiency will also decline so less CL is produced even with sufficient amps and the amount of CL generation has degraded so much, that you may not be able to generate enough CL within your run period.

Great info! Thanks!

 

[mas985]

I would think that the amps would be proportional to the amount of chlorine generated unless the amps are doing something else?

As I posted over in that other thread, the T-15 is only about 50%-60% current efficient. So the other "amps" go into producing side reactions, mostly oxygen as it has a lower standard reduction potential than chlorine although a higher over potential. If all the current went into CL produce, the T-15 would be able produce 3.36 lbs/day at 8 amps. In reality, it produces the published value of 1.45 lbs/day at about 6.5 amps which is about 53% efficient.

The first three columns in the table below represent measured scenarios while the last is at 100% efficiency.

Parameter	T-15	T-15	T-15	T-15 Ideal
Published Production (lbs)	1.45​	1.45​	1.45​	1.45​
Production Time (hours)	24​	24​	24​	24​
Nominal Voltage (volts)	25​	25.9​	26.44​	25​
Current (amps)	7.24​	6.5​	4.72​	8​
Series Cells/Group	6​	6​	6​	6​
Parallel Cell Groups	2​	2​	2​	2​
Estimated Current Efficiency	52%​	53%​	57%​	100%​
1 mole of electrons (Ah)	26.8​	26.8​	26.8​	26.8​
CL2 Molar Mass (g/mole)	70.906​	70.906​	70.906​	70.906​
Volts per Cell	4.17​	4.32​	4.41​	4.17​
Effective Total Cell Current (amps)	43.44​	39​	28.32​	48​
Total e- Moles	38.90​	34.93​	25.36​	42.99​
Total CL2 Moles	19.45​	17.46​	12.68​	21.49​
Ideal CL2 Production (lbs)	3.04​	2.73​	1.98​	3.36​
Estimated CL2 Production (lbs)	1.58​	1.46​	1.13​	3.36​
Percent of Published	109%​	101%​	78%​	232%​

 

[Chuckiechan]

Ooh, I gotta use that the next time I'm in a thread trying to justify the use/purchase of an SWG. I'd pay $100 a year just for the toting, even if I had to pay for the chlorine above and beyond that. Pretty sweet deal. I should go out today and do something nice for my SWG...

Buy it a nice cold glass of muriatic acid!

 

[Saturn94]

High salt alarms only occur when you exceed the amp limit.

That is what I did with my last two cells. I only have a choice of the T-15 and the T-5. Even though the cells degraded quite a bit, the T-5 setting generates alarms and shuts the cell down (> 5A) so I stuck with the T-15 setting. Anyway, changing the cell type really doesn't do much other than change the readout for salt and the amp limits. As the cell degrades, the cell efficiency will also decline so less CL is produced even with sufficient amps and the amount of CL generation has degraded so much, that you may not be able to generate enough CL within your run period.

Out of curiosity I pulled out my records from 2015 when the cell was replaced last. The old cell was reading 2500 ppm salt and the actual level was 3000 ppm. Knowing what I know now, perhaps I replaced that cell prematurely?

I still have the old cell; it’s been sitting in a closet since 2015. Is there any reason this cell might not still work after sitting in the closet that long?

 

[JamesW]

I still have the old cell; it’s been sitting in a closet since 2015. Is there any reason this cell might not still work after sitting in the closet that long?

It might work. Worth a try.

 

[Saturn94]

UPDATE:

I’m happy to report the current T15 cell has worked fine the rest of this season using the T9 setting on the controller. Yay!

Next season I’ll see how much longer the current cell will last on the T9 setting. When it gives out, I’ll try the old T15 cell that’s been sitting in the closet since 2015 and see if it has more life left.

 

[Dirk]

Consider leaving one of your cells with some life in it in storage. That way you'll always have a backup should the active cell fail. Now that you know your active cell is working and has some life, switch to the older "closet cell" and wear that one out. Then switch back to cell "A" while you're waiting for the replacement to arrive. Then put the newer one online and store "A" in the closet. Rotate the 2nd newest near-end-of-life cell to the closet, and use up the oldest one before putting the newest one online.

Murphy's Law (Section 136, Paragraph 16) mandates your active cell will fail the day before you leave the house for a week-long vacation. You're backup cell will ensure your pool will be fine until you get back...

 

[Saturn94]

Consider leaving one of your cells with some life in it in storage. That way you'll always have a backup should the active cell fail. Now that you know your active cell is working and has some life, switch to the older "closet cell" and wear that one out. Then switch back to cell "A" while you're waiting for the replacement to arrive. Then put the newer one online and store "A" in the closet. Rotate the 2nd newest near-end-of-life cell to the closet, and use up the oldest one before putting the newest one online.

Murphy's Law (Section 136, Paragraph 16) mandates your active cell will fail the day before you leave the house for a week-long vacation. You're backup cell will ensure your pool will be fine until you get back...

Good idea.

 

[Saturn94]

UPDATE:

@JamesW

The pool is open and earlier this week I installed the oldest T15 salt cell I have (purchased 2008, replaced 2015). So far it is maintaining FC on the T9 setting. I’ll keep the “newer” T15 cell (purchased 2015) on standby to use when the oldest cell is depleted. Maybe with some luck I can make it through this season without having to buy a new cell.

Any faults in my plan I‘m not seeing?

 

[DeanP66]

Your average yearly chlorine cost just keeps shrinking and shrinking.

 

[JamesW]

UPDATE:

@JamesW

The pool is open and earlier this week I installed the oldest T15 salt cell I have (purchased 2008, replaced 2015). So far it is maintaining FC on the T9 setting. I’ll keep the “newer” T15 cell (purchased 2015) on standby to use when the oldest cell is depleted. Maybe with some luck I can make it through this season without having to buy a new cell.

Any faults in my plan I‘m not seeing?

I think that you have a pretty good plan.