Hayward system shows normal readings but chlorine not being generated

[philipaby]

Hello,
I have a 20000 gallon pool that's been running on a salt system for a few years now. The last time I replaced the T-15 cell was 4 years ago. Earlier this year I had the pool acid washed and refilled, added salt etc to get it going. Somewhere along the way, a rabbit/squirrel chewed a small part of the wire from the cell to the display. I fixed that portion and everything was back to normal for a few months.
Recently my pool tech noticed that the chlorine levels were really low recently about 0.5 ppm. He comes by once a week to check and maintain. Oddly enough the display shows values in the normal range (as listed below). That's been the case for a while now. But the chlorine always showed really low.
Yesterday he checked the pool salt with a strip and it read 6600! He thinks the cell might be bad (he had inspected it for cleaning and it was clear) and we will need to replace. So looking to replace the cell and add water to the pool to bring salt levels to normal.

• 2900
• 77
• 26
• 5.6
• 70
• 3000
• Product name
• r - 1.59
• t-15

Anything else that you might see that we are missing? Also while diluting the pool he suggested that I add tablets to the skimmer to maintain chlorine until he comes Tuesday. But I've seen folks state that adding liquid chlorine is the way to go. Any help or advice would be much appreciated!

Thanks in advance!
Regards
Aby

20K Pool and Spa
Hayward Salt system
V-Green Evo Variable Speed pump

 

[ajw22]

First thing you need to do is get a good test kit - Taylor K-2006C or TFT Test Kits with the salt test.

Then you need to drain your pool at least 50% to get your salt level into the 3,000's.

Draining - Further Reading

www.troublefreepool.com

After 4 years of use in Texas there is a good chance your dell is depleted and needs replacing.

We never recommend putting tablets in the skimmer. The acid in the tablets will destroy your equipment. If you must use tablets, put them in a floater.

Liquid chlorine gets the chlorine level up faster then tablets.

Liquid Chlorine - Further Reading

www.troublefreepool.com

 

[JamesW]

• 2900
• 77
• 26
• 5.6
• 70
• 3000
• Product name
• r - 1.59
• t-15

77 degree pool water in Texas today?

 

[JamesW]

You can change the cell type to T-9 to get some extra life from the cell.

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.

Cell Diagnostics.​

Pressing the diagnostic button sequentially will display:

• Default salt display
• Pool temp
• Cell Voltage - When not generating, the voltage is about 30 to 32 volts dc. When generating, the voltage drops about 1 volt per amp of current.
• Cell current
• Desired output (% of the knob)
• Instant salinity
• Product name
• Software revision (r.XX)
• Cell type

 

[JamesW]

Taylor K-1766 Salt Test Kit

tftestkits.net

TF-Pro Salt

tftestkits.net

 

[philipaby]

Thanks JamesW & ajw22 for your responses. Like you both said and based on the formula, this cell definitely needs replacing. Thanks for the article on liquid chlorine. I'd never had to do the chlorine maintenance myself hence this bit is new to me. I'll do accordingly.

Yes, I did think it was interesting that the temp was 77 on the display, but I just checked again and it's showing the same thing. Don't know if that's something else wrong because of the cell being bad.

Regards
Aby

 

[JamesW]

What is the actual water temperature?

The temperature affects the accuracy of the salinity reading.

 

[philipaby]

Hi JamesW,
Apologies for the delay in responding. Was out for a bit and then a hurricane just came through Houston and the eye passed through our side so we were out of power etc for a while.

I did check the temperature separately and it was showing 87 at 7 pm.

Right now as you said, I'm using liquid chlorine to keep the levels at par and hopefully we can replace the cell on Friday. Will keep you posted on how it goes.

Thank you!
Aby

 

[philipaby]

Hi JamesW,

This is going to be embarrassing on a couple of fronts. As mentioned before, pool tech (Ted) told me he saw 6600 ppm for salt readings on the water. And he asked me to use my salt strips just to be sure and I noticed the strips saying something in that range (6K +). So I drained about 6-7000 gallons out to reduce the salt ppm and did the test again from my end. Noticed the strips were now showing 4.8. Here's where I wanted to kick myself. The strip has a 1-10 number range and I assumed that 1 would be 1000 ppm, 2 would be 2000 ppm and so on. When I looked on the back of the bottle, looks like it's scale was different i.e. 4.8 reading meant 1600 ppm!! So looks like I ended up draining and filling for nothing! Felt like an idiot myself.
So Ted comes by and replaces the salt cell (which we suspected was not working to begin with) and does the salt test and he says that it's still showing 4000 ppm! At this point, both of us figured we'd go and get a reading from the pool store to see what was going on. Pool store says that the salt level was 1500 ppm just like the strips. So Ted (who uses a Taylor kit) is thinking there might be something going on with his salt tests.

Anyway, replaced the cell, I add a few bags of salt to get it to 2800 ppm and looks like chlorine is finally being generated! Even the pool temp is now showing 86 which is more in line with reality! I did the test with reagents and chlorine is above the 3 ppm mark. I can also see bubbles coming out of the jets. Hopefully I can get this stabilized and then I can see whether the few areas where small specks of blacks algae stop spreading. I did the whole scrub with metal brush and then chlorine tablet directly on it etc but this pool never had enough chlorine the past 2 months. Will see where this goes.

Either way, thanks for helping me out with the SWG issue. I hope this one keeps working long enough. Also lesson learned in that I do my own tests once a month or so just as a second pair of eyes and make sure it matches with what Ted sees every week.

Regards
Aby