Should I switch from T-15 to T-9 cell?

[DukeNelson]

Evidence suggests my 4-season-old Aqua Rite T-15 cell is no longer producing chlorine. Water is balanced, cell is clean and there are no bad indicator lights so I am assuming the cell has reached end of life. I am considering a replacement cell.

My estimate of pool volume is 24k gallons. A T-9 cell should cover this size (up to 25k) but the original contractor chose and installed the T-15. I'm not sure why.

Can I save the money and use a T-9 with the existing control unit? Would I have to replace the unit, or make some firmware update (as was hinted on some internet site I found). Or should I stick with what worked for 4 years and pay the premium for another T-15 cell (and replace it with no control unit changes).

Thanks.

 

[Bama Rambler]

I'd stick with the T-15. But before you do that post a full set of test results and how you got them. Also post the cell voltage and amperage. There may be something else going on.

 

[PoolGuyNJ]

As to why the T-15 over the T-9 cell, cells can be On for only so long. The smaller unit will need to be On far more than the larger cell. ergo the larger cell will last longer and the difference in cost isn't enough to Not do. It just makes sense,

Scott

 

[Poolschoolgrad]

"Evidence suggests"
What evidence would that be?

Proper water balance for a Salt system is essential for optimum performance.
pool-school/water_balance_saltwater_generator

A lower than recommended CYA level can allow sunlight to consume chlorine quicker than the unit can produce it.

To test the cell:
Sequentially press the diagnostic button and post the following:
1. Temp
2. Cell voltage
3. Cell current
4. output %
5. salinity
6 produt name
7. Software revision level

Cell voltage should be 22 to 25 volts when generating otherwise 30-35v
Cell current is normally between 4.5 and 7.8


For a t-9 to work on that size pool would probably require 24/7 pump run times. In areas with high electricity rates, you could pay for a new t-15 cell every 3 years for the amount of extra electricity you will need for the additional pump run time for the smaller t-9 cell. The T-cell-15 is the correct choice.
If funds are the issue, then consider the GLX-CELL-15 which is the same cell as the t-cell-15 but with only a 1 year warranty.

PSG

 

[DukeNelson]

Thanks for the quick replies. I'll accept the advice that sticking with a T-15 is the way to go. That leaves the question of whether my existing T-15 is defective or not. The readings in order are

1. 2900 (Salinity)
2. 92 (temp)
3. 29 (voltage)
4. 5.27 (current)
5. 99P (output%)
6. -2800 (Instant salinity)
7. AL-O product
8. r 1.40 revision

No red/yellow/blinking lights - just the two green lights showing that it is generating.

As far as chemistry is concerned

- PH is in range.
- Chlorine is negligible even after running the pump for 36 hours.
- Cyanuric acid has been a concern. It shows low on test strips, even though a pool shop test a few weeks ago showed 60 ppm.

Most of the week, a clear bubble solar is on the pool. In previous years we used a blue/silver cover. As the clear one allows more sunlight I wonder if it contributes to more chlorine loss.

Thanks for your advice.

 

[Bama Rambler]

You need a good test kit!

We love and need numbers!
pH =
FC =
CC =
TA =
CH =
CYA =
Salt = (from a test, not the cell)

Take a sample to the pool store and get them to test it for you. That's better than nothing.
Add some bleach in there to get to 5 ppm. That'll take about 1½ large jugs. The sooner the better.

 

[JasonLion]

Your diagnostic numbers don't suggest any problems with the cell wearing out. It is getting older, so I wouldn't expect it to last forever, but just at the moment is seems fine, as far as the diagnostic numbers can tell us. Most likely you have some problem with water chemistry, so posting a full set of water test results is the next thing to try.

 

[DukeNelson]

Numbers provided as requested - admittedly one month ago from the pool store (Leslie). (Since then we have used a floating chlorinator with a few tabs prior to using the pool but as soon as we stop using it and try the Aquarite we see no noticeable chlorine using the test strips)

pH = 7.4 (OK)
FC = 0
CC = 0 (I assume this is the Total Available chlorine, abbreviated by Leslie's as TAC)
TA = 90
CH = 210
CYA = 60
Salt = (from a test, not the cell)

Phosphates were High at 300 and after that test have put in Phosfree as directed by the store.
Probably time for a new store test I'm sure you'll say

 

[Bama Rambler]

Probably time for a new store test I'm sure you'll say

No, that's not what we'll say! What we'll say is that it's time for you to get your own good test kit! That's, what we'll say. So, why haven't you gotten one yet??

A month old test is all but useless and from a pool store doesn't make it any better. Go ahead and order a TF-100, but in the mean time take a sample back to the pool store and let them test it and post the numbers. That'll have to do till you can get a test kit.

 

[dschlic1]

From personal experience is is possible to have a SWCG operating correctly and still have 0 FC!

 

[Aquatica]

get a T15...a T9 will struggle..it is best to have more and turn down the %. there is also a replacement for the T15..a little cheaper but see-through and not good for outside use as chlorine production won't be as effective as UV rays will break it down. but good replacement for the T15 for inside a pump house. its made by CompuPool.

 

[DukeNelson]

Hi - original poster back again...

From personal experience is is possible to have a SWCG operating correctly and still have 0 FC!

This seems to be the case with mine. Following advice above I revisited my pool chemistry, and concluded the problem was low stabiliser in the pool chemistry. Along the way I learnt a few things.

- Using test strips from last year (but within their use-by date) the Stabiliser indicator had become inaccurate. Comparing side-by-side strips from old and new kit, the other indicators had matching colors by the CYA indicator evidently ages badly.

- On the local pool store's (Leslie) water analysis chart a "30" for Cyanuric acid scores an "OK" (bottom of their OK range) but is insufficient in our pool to conserve the chlorine produced. Indeed the manual for the Goldline says (I think from memory) 60 ppm is needed but I may be mistaken.

- The same store's salt reading from an in-store test was lower than that our salt test strips and our SWCG control panel. Had we added the extra salt they proposed I suspect our SWCG would have gone off the high end of the scale and stopped producing.

- A visit by a technician proved fruitless because (a) he was not issued with a dummy to replace the SWCG. (I have since bought my own, which will come in handy, and (b) as I wasn't there to point out the floating "backup" chlorinator with tabs he tested the water and concluded the SWCG was producing the chlorine.

- When I do eventually replace my SWCG I will stick with a T-15 based on advice above. (This was the original subject of my post)

Thank you all for your help.