SWG failure and high salinity

[yaximik]

My Aqua Logic system shows "salinity too low" (zero), so SWG (Goldline T-Cell 15) is obviously off. However, when I tried to test salinity with the K-1766 Tailor kit, salinity apparently was so high that after 30 drops I still could not reach the color change, which means it is higher than 6000 ppm.

Why then the system shows salinity too low? Does the T-cell measure salinity? This would mean either the cell went bad or it just shut off because of high salinity - which is correct?

Is there a separate unit in the system that measures salinity? Then this unit could be bad and may be I do not need to replace a $600 T-cell.

I get the pool with the house, so I do not know how old the cell is, the pool was built in 2006. The T-cell inside shows just little yellow-orange coloration.

Any advice?

 

[Teald024]

If the SWG is reading very low compared to the actual as testing levels, then it is an indication that the cell is either full of scale or is going bad. Look inside the cell, are the plates covered in white crust? That would be the scale. If it isn't covered in scale then it may be bad. Check the date code. The serial should start with something like 3E15 or 3E16. 3 is number of years of the warranty. E means cell. Then the next two are the year of manufacture. That will tell you when it was manufactured and how old it is. You would be very lucky if you have the original cell from 2006 (~12 years old)

The cell measures how conductive the water is by measuring the voltage across the plates inside. There is no separate thing and nothing else to replace, assuming it's not the controller.

As a side note, how did salt get to 6000 ppm, that's almost twice the recommended salt levels?

Until the SGW is fixed / replaced, you will need to dose with liquid chlorine to keep your pool sanitary.

 

[yaximik]

Thanks a lot for useful info. I just purchased the house, so I inherited all previous owner's achievements. I try to get a second opinion on salinity level, may be from local pool service folks, but looks like I need to drain the pool and refill it to start fresh. It may be not only salt, the TDS may be too high as well.

 

[JamesW]

As the cell fails, the salinity reads low on the board, so many people rely on the board reading and keep adding salt. This causes the actual salinity to keep rising until the cell fails completely.

Check the cell's serial number for age.

Double check salinity with a k-1766 test kit.

 

[Teald024]

If you haven’t done so yet, you should get a good test kit on order (TF-100 or Taylor K-2006C). With the TFP method, the TDS doesn’t matter. You only need to test for FC, CC, pH, TA, CH and CYA. In you case, salt also but you have that kit already K-1766.

 

[JamesW]

Do the salt test again, but go until you get a color change.

Maybe dilute a pool water sample with half distilled water and half pool water. Mix well then test for salinity and double the result.

 

[yaximik]

The data code is 5E0604-2074540. Wow, although the cell was with 5 yr warranty it is indeed 12 years old! Is it possible that the cell works that long? Goldline T Cell-15 TurboCell, I see it is available online, but maximum I can find now is 3 year warranty.

 

[JamesW]

They can work that long, but it's unusual. 5 to 7 years is typical.

They stopped the 5 year warranty and changed to 3 years.

The TCELL940 is a "Long Life" T-15 and has a 4 year warranty.

 

[yaximik]

I have retested salinity with K-1766 using dilution factors 2 and 3. The color conversion points were now achievable at 23 drops and 16 drops, respectively, which gives salinity of 9200 ppm and 9600 ppm, or 0.92% and 0.96%. Wow, that is like medical normal saline! So, I have to drain 3/4 of the pool and refill with fresh water to get to about 2400 ppm. Good thing that in Oregon water is not expensive, it's ~15 ccf for my 15000 gal pool. Pool service service folks advised me against draining 3/4 at once to avert possible pool popping out, and instead drain and refill about 1 ft in depth at a time. With no mixing after each refill I hope I can take advantage of the slight difference in water density to achieve faster withdrawal of salt and stay close to 15 ccf of fresh water. Otherwise it will take more water and time to arrive at the target salinity level. My calculations show that with mixing after draining and replacing 1 ft at a time salinity decreases to 0.78 of the starting value each time, so it needs to be done 5.5 times to reach target 0.24% using ~25 ccf. I am having fun this weekend...

I looked up what options are available for new Hayward Goldline T Cell-15 and on Amazon I see two essentially identical bundles (cell+stand), same 3 yr warranty, for ~$470 from Pool Supply Warehouse (through Amazon) and and ~$446 from Amazon. Any advice on choice of merchant or merchandise?

 

[JamesW]

If you get the salinity below about 4,000, it should work as long as the water temperature is below about 74 degrees.

The higher the water temperature, the lower you need to get the salinity.

In any case, you shouldn't need to go below 3,200 ppm.