Replace aging TCELL940 with TCELLS340 ?

tech135797531

Well-known member
Jun 14, 2019
53
FL
My TCELL940 (paired up with an Omni PL system) seems to be slowing down after nearly 5 years of operation. It was fine last season (operating at 20-25% trough the NE FL summer/fall) and kept the pool at 5ppm running at 5% with a pool cover Dec-Feb. But now that I've uncovered the pool, it looks like I need to keep it around 50% to maintain and that's with air temps in the 60-70s, salt at 3400, CYA at 60. I've cleaned it 3 days ago but it was pretty darn clean. So I'm assuming that we're approaching eol.

Anyway, should I try to get another 940 or should I switch over to the new S340? It's still unclear to me what the S3 line does differently than the old generation other than the fact that it looks "fancier" which I could care less about. Any suggestions? Thank you!

PS - out of curiosity, what happens to a salt cell if the salt level is slightly too high (eg 3600 which would be 200 over the recommended threshold)? It's not the case here but I've been in that situation before after adding a bunch of liquid chlorine which turned into salt after being used. The cell was still producing, but does it produce less?
 
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What is the actual salinity (using a salinity test kit) versus the instant salinity reported by your system?
 
What is the actual salinity (using a salinity test kit) versus the instant salinity reported by your system?
Hey there! Using the K-1766 (which granted, shows an expiration date on the bottles of 9/23) I'm getting 2800 (14 drops), so Im on the lower end. The salt cell shows 3350. Which one do I trust? Probably the k-1766 even if a bit expired. I guess I can add half a bag of salt to see if it makes a difference?!

Either way, my question stands, what's the difference between the 940 and the s340?

Thank you for your help!
 
No, do not add salt if the OmniPL is happy with the salt level.

What is the diagnostic information for the chlorinator?
 
Either way, my question stands, what's the difference between the 940 and the s340?

There is not functional difference.

It is believed that the S3 cells have a chip to indicate the cell is genuine Hayward that the newer Hayward systems check to ban use of generic cells.
 
I'm getting 2800 (14 drops), so I'm on the lower end. The salt cell shows 3350.
3,350/2,800 = 1.196

Your cell is producing at about 1.2 times expected performance.

At 120% performance, the cell is fine.

To get the performance of the cell, divide the instant salinity by the actual salinity.

If the ratio is less than 75%, it's time for a new cell.

For example, 2,000 (instant salinity) ÷ 3,600 (measured salinity with a test kit)=56%.

Check the cell and clean it if necessary.

If that doesn't work, it's time for a new cell.

Are you sure that the correct Cell Type is selected in the configuration menu?

Try an OCLT.
 
Hey guys, I already did the OCLT 3 nights straight and I lose about 0.5ppm. Today it was a cloudy rainy day so with the cell at 40% the pool stayed steady. Salt is, as I mentioned 2800 by my test, 3350 instant salt according to the cell. CYA is 60 and the FC is exactly where it needs to be. And no one is swimming by the way these days. Like I said, I cleaned the cell with muriatic acid (2:1 water:acid ration) 3 days ago but it was already clean.

The cell is and has always been recognized as a T-Cell-15. Cell voltage is 31V in standby and 26V when running with the current being 5.8A. So really nothing has changed since Nov-Dec other than the fact that I need to keep it at 40% to keep up on a cloudy day like today, higher on a sunny day. That's why I was thinking that the TCELL940 was starting to slow down after 4.5 years (installed August 2019). Anything else I could check or do I just need to get ready for a new SWG?
 

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That amperage is a little bit low.

Double check to make sure that the cell is configured as a T-15 in settings.

If the cell is configured as a T-15, the cell is fine as indicated by the percentage test.
What would be the right range for the amperage?

How many hours of runtime?

What is the water temperature?
Water is 67-70 these days. I run the pump 8am to 8pm


Omni PL’s will give you the option to choose the exact cell. It should say 940 or 340. Make sure to have the cell unplugged before choosing the correct one.
I understand and I'm sure it does. But It's been set as T15 since the day I installed and has worked fine. So this can't be the issue



Again, nothing has changed since it was working fine in December, it's just that now I need a more than double %: CYA is 60, FC is 5, Omni PL configuration is unchanged, OCLT passes with flying colors, pump runtime is unchanged and I just cleaned the cell. I just assumed that it was the 940 slowly dying. I'll add half of bag of salt so that the K-1766 can read 3000 instead if 2800. In the meantime I'll start looking for an old stock 940 or an S340 although I was really hoping to figure this out without the expense. Thanks guys!
 
You were using a cover & now you’re not so the sun is also a big factor. Since you’ve passed oclt you may want to ensure your cya is a solid 70ppm & see if that doesn’t help. Here’s approx what your current settings should be producing under optimal conditions.
IMG_9399.png
3ish ppm fc consumption on a high uv florida day is not terribly uncommon with a lowish cya.
You can also do an overnight chlorine gain test to see if you are getting close to optimal production when compared to
PoolMath effects of adding estimates for your cell.
The gain test is like the oclt only opposite.
You have eliminated algae as the cause by passing oclt. The ocgt also removes the sun from the equation.
The swcg is on & you test after dark & before dawn to see what your fc gain is.
 
Your cell is producing at about 1.2 times expected performance.

At 120% performance, the cell is fine.

So, your assessment of the cell underperforming is not accurate or the actual salinity is not accurate or the cell size is not set correctly.

Did you actually check the cell setting or are you assuming it is correct?

Check the actual salinity 3 different independent ways to verify.

I never trust any single salinity test.
 
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