Is my SWG dying?

[LordNorth]

Have had the pool open for several weeks, and the water is absolutely beautiful. Clear and sparkling.

My test numbers:
Water Temp: 75
Salt 2900 (a little low, but should not be significant)
CYA 60
pH 7.4
TA 50
FC 3

Previous years my SWG would easily keep me in the 4-6 FC range at 30%. This year I have it up to 45% and can't seem to get it above 3.

My generator is about 5 years old and has 32,000 hours on the cell. The plates are all clean and shiny.

Am I looking at a replacement cell, or is there something else that I might be missing? Any other tests that I should look at?

Thanks.
Chris

 

[Rancho Cost-a-Lotta]

You should perform and Overnight Chlorine Loss Test and make sure the reduced FC is not the result of unseen organics.

How long are you running the pump with SWG set at 45%?

 

[jedigrover]

Does the salt cell's controller give you a salt measurement? Is that the 2900 you quote above?
Have you tested your salt level independent of what the cell tells you?

In my experience, when a cell starts to go out, it will report low salt levels. If you don't independently check your salt level, then you will add salt and the cell continues to report low salt...you can wind up way over-salting the water this way.

If you see a big discrepancy between what the cell reports for salt level versus your independent test, and you see production falling off like this, then yes, the cell could be going bad. Some pool stores have a tester for the cell. Depends on the brand and whether they have that equipment. I suspect it's just looking at the volts & amps.

My Goldline/Hayward reports volts and amps. High Volts / Low Amps on a clean cell with proper concentration of salt usually means depleted cell. Check the troubleshooting guide in your manual.

 

[LordNorth]

You should perform and Overnight Chlorine Loss Test and make sure the reduced FC is not the result of unseen organics.

How long are you running the pump with SWG set at 45%?

I have a variable speed pump, so it runs 24/7.

I did a good SLAM to open, and like I said, the pool is beautiful to look at, but I am getting a lot of 'dirt' on the bottom of the pool, so maybe I'll have to look at that.

Thanks!
Chris

 

[LordNorth]

Does the salt cell's controller give you a salt measurement? Is that the 2900 you quote above?
Have you tested your salt level independent of what the cell tells you?

In my experience, when a cell starts to go out, it will report low salt levels. If you don't independently check your salt level, then you will add salt and the cell continues to report low salt...you can wind up way over-salting the water this way.

If you see a big discrepancy between what the cell reports for salt level versus your independent test, and you see production falling off like this, then yes, the cell could be going bad. Some pool stores have a tester for the cell. Depends on the brand and whether they have that equipment. I suspect it's just looking at the volts & amps.

My Goldline/Hayward reports volts and amps. High Volts / Low Amps on a clean cell with proper concentration of salt usually means depleted cell. Check the troubleshooting guide in your manual.

Thanks for the info. Yes, the controller gives me the reading. My system salt reporting has always been really good, so I haven't bothered to check it. Guess I will give that a try and see what I get.

I'll see if I can find the voltage/amperage readings.

Thanks!
Chris

 

[jedigrover]

I don't know specifics of the Pentair SWGs, just the Hayward like I have. On the Hayward, there isn't an actual extra salt sensor in the cell. Instead, they have tables in software to compute the salt reading based on Voltage, Amperage, and Temperature. So if the cell is going bad, then the salt reading is bad too.

A rule of thumb on the Haywards is to go to it and take an "instant salt" reading (what does it think right now, without any averaging of prior readings) and compare it to an independent measure of salt (like with the Taylor drop test or another meter that matches calibrated solution well). If the (clean) SWG's view of salt ppm is less than 75% of the real salt level, then the cell is failing.

Again, I don't know how the internals of the Pentair cell work & whether they use an independent probe or not.

 

[Rancho Cost-a-Lotta]

Do you the rated chlorine production rate of the SWG (in lbs per/day)?

I did some research on the RC42 SuperCell and it appears to be a replacement for the Autopilot PPC3. If that's correct, the SWG produces 1.56 lbs of chlorine gas per/day. Running it at 45%, 24 hours, will increase FC in your pool by 2.5 ppm. That's probably close to your daily loss.

You might try using liquid chlorine to bump FC up to target level and see if the SWG can keep up.

If you pass the OCLT, you could run an Overnight Chlorine Production Test to determine if the SWG is producing at it's rated capacity.

 

[LordNorth]

I don't know specifics of the Pentair SWGs, just the Hayward like I have. On the Hayward, there isn't an actual extra salt sensor in the cell. Instead, they have tables in software to compute the salt reading based on Voltage, Amperage, and Temperature. So if the cell is going bad, then the salt reading is bad too.

A rule of thumb on the Haywards is to go to it and take an "instant salt" reading (what does it think right now, without any averaging of prior readings) and compare it to an independent measure of salt (like with the Taylor drop test or another meter that matches calibrated solution well). If the (clean) SWG's view of salt ppm is less than 75% of the real salt level, then the cell is failing.

Again, I don't know how the internals of the Pentair cell work & whether they use an independent probe or not.

Checked the salt... Turned red right at 15 drops, so the salt indicator is dead-on.

Here is my amp/volt readout...

I am getting a CC of zero, so maybe I am just right on that edge of using exactly as much chlorine as I'm making each day. I bumped up to 75%, and I'm going to hit it with liquid chlorine to see if I can break out of it.

On the upside, despite this... this is what the water looks like... If you zoom, you can easily see the pebbles in the liner and the holes in the drain. Not cloudy in the least.


Thanks.
Chris

 

[LordNorth]

Do you the rated chlorine production rate of the SWG (in lbs per/day)?

I did some research on the RC42 SuperCell and it appears to be a replacement for the Autopilot PPC3. If that's correct, the SWG produces 1.56 lbs of chlorine gas per/day. Running it at 45%, 24 hours, will increase FC in your pool by 2.5 ppm. That's probably close to your daily loss.

You might try using liquid chlorine to bump FC up to target level and see if the SWG can keep up.

If you pass the OCLT, you could run an Overnight Chlorine Production Test to determine if the SWG is producing at it's rated capacity.

Thanks for the suggestion. I'm wondering if maybe I'm right on the edge and you are right that it burning off the same amount of chlorine I'm producing. The CC is reading 0 though, so I just don't know.

I'm going to bump it up to 75% and try the liquid chlorine idea and see what I end up with. Fortunately, the water is clear so it can't be TOO awful.

Chris

 

[Rancho Cost-a-Lotta]

Thanks for the suggestion. I'm wondering if maybe I'm right on the edge and you are right that it burning off the same amount of chlorine I'm producing. The CC is reading 0 though, so I just don't know.

I'm going to bump it up to 75% and try the liquid chlorine idea and see what I end up with. Fortunately, the water is clear so it can't be TOO awful.

CC is combined chlorine. A result of 0.0 is perfect. Anything over 1.0 ppm indicates a potential problem.

If your FC has been stable day-to-day, 2.5 ppm may be your number this time of year. Just bump FC up to target level with LC and test to confirm the SWG is keeping up.

Good pics of the pool. You know your pool is TFP clear when you see whether the drain screws are standard or phillips.

 

[LordNorth]

CC is combined chlorine. A result of 0.0 is perfect. Anything over 1.0 ppm indicates a potential problem.

If your FC has been stable day-to-day, 2.5 ppm may be your number this time of year. Just bump FC up to target level with LC and test to confirm the SWG is keeping up.

Good pics of the pool. You know your pool is TFP clear when you see whether the drain screws are standard or phillips.

Thanks for the suggestions. I'm still kind of concerned that it isn't keeping a high enough output, but as I said, maybe if I knock the edge off the little bit of gunk that I might have going on that it'll be able to bring it back down to a more typical setting.

Thanks.
Chris

 

[Rancho Cost-a-Lotta]

maybe if I knock the edge off the little bit of gunk

Back to Plan B. Do the OCLT