Salt Cell Running at Low Water Temps

[cznkane]

I'm fully aware of the lower water temps having an impact on production. My question is: does having the salt cell operating (and not producing much) at lower temps cause any unnecessary wear and tear / build up or is it only a matter of a lack of production?

 

[reggiehammond]

No - no issue.

My water temps at up to 65-70ºF here... Already producing.

 

[cznkane]

No - no issue.

My water temps at up to 65-70ºF here... Already producing.

Great, thank you. Temps have been all over the place here and I just wanted to know if I need to keep going out there and turning it off and on. I see you're a little north of me so I'm sure you've had the same water temps going up and down.

 

[reggiehammond]

Great, thank you. Temps have been all over the place here and I just wanted to know if I need to keep going out there and turning it off and on. I see you're a little north of me so I'm sure you've had the same water temps going up and down.

Last few years, mine has kicked on around last week of February. If not careful, you can have a good algae bloom going by Spring Break as temps really skyrocket with longer days and warmer temps. My kids will be in the pool by March 30, though a bit chilly for any sane adult.

 

[Newdude]

If production suffers its kinda a moot point. The UV loss will be next to nothing also if it's that cool out.

 

[cznkane]

If production suffers its kinda a moot point. The UV loss will be next to nothing also if it's that cool out.

Yup...but I think you miss the question. It isn't at all about production. It is about the health of the cell.

 

[Dirk]

@JoyfulNoise?
Cells produce for a finite number of hours. If the plates are producing less chlorine due to cold water, do they wear out less? Or do they wear out based on number of hours they are energized, regardless of chlorine produced?

 

[Newdude]

Yup...but I think you miss the question

Oh I got it. And it was already answered.

I was making the related point for future readers who find this. After learning cool water doesn't hurt the cell, they'll likely wonder what they should be doing instead and the answer is they don't have to watch FC like a hawk when it's too cold for the cell. Supplemental liquid chlorine might last a week or more betwern adds at that point

 

[JoyfulNoise]

I'm fully aware of the lower water temps having an impact on production. My question is: does having the salt cell operating (and not producing much) at lower temps cause any unnecessary wear and tear / build up or is it only a matter of a lack of production?

@JoyfulNoise?
Cells produce for a finite number of hours. If the plates are producing less chlorine due to cold water, do they wear out less? Or do they wear out based on number of hours they are energized, regardless of chlorine produced?

You rang ..

Short answer - energizing the cell, no matter what it produces, wears out the plates. The coating on the cell plates has a finite lifetime no matter what.

Slightly longer answer - when the water is cold, chlorine gas production from brine becomes less and less efficient. Oxygen gas generation increases. The catalyst material (ruthenium metal) is still doing work, it's just not doing the work you'd like it to do ... kind of like me on my days off, I'm doing work, and we all come with an expiration date, I'm just not doing the work everyone else thinks I should be doing

 

[cznkane]

@JoyfulNoise?
Cells produce for a finite number of hours. If the plates are producing less chlorine due to cold water, do they wear out less? Or do they wear out based on number of hours they are energized, regardless of chlorine produced?

Bingo! That is the exact question

 

[cznkane]

You rang ..

Short answer - energizing the cell, no matter what it produces, wears out the plates. The coating on the cell plates has a finite lifetime no matter what.

Slightly longer answer - when the water is cold, chlorine gas production from brine becomes less and less efficient. Oxygen gas generation increases. The catalyst material (ruthenium metal) is still doing work, it's just not doing the work you'd like it to do ... kind of like me on my days off, I'm doing work, and we all come with an expiration date, I'm just not doing the work everyone else thinks I should be doing

Excellent info, that's exactly what I was after, I'll keep cutting the power to it if the water temp is sub 60*

 

[cznkane]

Oh I got it. And it was already answered.

I was making the related point for future readers who find this. After learning cool water doesn't hurt the cell, they'll likely wonder what they should be doing instead and the answer is they don't have to watch FC like a hawk when it's too cold for the cell. Supplemental liquid chlorine might last a week or more betwern adds at that point

Ah! Gotcha and good thinking, appreciate it

 

[cznkane]

 

[Newdude]

Personally, when it's on the fence, it would bother me more to wonder and have to find out if I was needed each day. I'd go out to the pool and learn that the SWG didn't produce, or didn't produce enough and I'd have to go get bleach from the garage. Next time I'd bring the bleach, *not need it* and have to go put it back.

One way or the other, I prefer getting into a groove and sticking with it.

 

[Dirk]

One way or the other, I prefer getting into a groove and sticking with it.

I think then, I've been doing it exactly right.

I could push my SWG into lower temps, to eek out a week or three of additional "SWG service," but it seems to me I'd be burning up my precious SWG lifetime hours for less than optimum chlorine output. Further, because the chlorine output might vary from day to day, as the borderline temperature varies day to day, I couldn't rely on the pool maintaining a consistent FC each day. So...

When my pool water first hits about 54°F, I shut off the SWG. I then test and dose liquid chlorine once a week. And I have to do that for about three months in the winter, so 12 times. And that is not much of a chore.

It assures me my pool's FC is stable throughout the winter, it increases by some amount my SWG's lifespan, and more importantly doesn't waste that lifespan.

Put another way, and to answer the OP's original question, running your SWG when the water temp is less than ideal doesn't "cause any unnecessary wear and tear / build up," but you are in fact burning lifespan at a lower ROI on the cost of the SWG cell. I'll have to leave it to someone else to determine if the actual expense of running an SWG inefficiently in winter costs more or less than the cost of liquid chlorine.

 

[Newdude]

but it seems to me I'd be burning up my precious SWG lifetime hours for less than optimum chlorine output.

It's both entirely true and also peanuts. I'm down to 4 % or less @ 24/7 runtime at that point, but let's use 4% (or any equivalent maths). It's one hour of production a day, and there may be 2 weeks that it can't make up It's mind, so 14 hours total were used. But it was only some inefficient in the cool water so maybe i lost 7 hours off the 10,000 hour lifespan.

My cell was $1800 so it costs $0.18 an hour to run. By saving 7 hours, I saved $1.26 over 2 weeks. Yes I preserved precious cell life, but no it meant nothing.

Said savings are then wiped out several times over with liquid chlorine costs. 14 hours is 4.1 FC at a cost of $2.52. 4.1 FC for me is 1.4 gallons of 10% or $8.70. I, or anyone, can afford to waste 7 hours at almost 1/4 the cost of LC.

However. The uncertainty of how much it worked today, if it worked, would drive me nuts so I'd pull the plug quick when it got cool to save my sanity, or whats left of it, not the cell life. People pinch WAY too many pennies with cell life IMO.

 

[JoyfulNoise]

Meh … I let it ride until the water gets too cold. There will be days where it flickers on and off with the sun but I just let it go. Then, after a few weeks of wondering if any chlorine is in the water, I do a test. It’s usually still pretty solid magenta. Then I ignore it some more. Then I remember to buy a gallon of 10% at the store and dump it in. Maybe a few weeks later I test again. Then the SWG kicks back on and I think “GREAT!! No more testing for chlorine … wait, when did I actually test for chlorine ”. Then at some point in April I start testing more regularly and my FC is somewhere between 50 and thermonuclear level cuz when the SWG runs in cool water with little UV loss, the FC goes through the roof …. Eventually I get it all leveled out sometime around May just when the kids start whining that they want to use the pool again ….

 

[jonpcar]

Short answer - energizing the cell, no matter what it produces, wears out the plates. The coating on the cell plates has a finite lifetime no matter what.

Slightly longer answer - when the water is cold, chlorine gas production from brine becomes less and less efficient. Oxygen gas generation increases. The catalyst material (ruthenium metal) is still doing work, it's just not doing the work you'd like it to do ... kind of like me on my days off, I'm doing work, and we all come with an expiration date, I'm just not doing the work everyone else thinks I should be doing

Matt, what can one expect for power usage of the SWG during the time ”it is actually producing chlorine” due to cold water? Would it be the same or less? I’m not asking to try and minimize my power cost…I’m asking if one could “determine” that the cell is producing less chlorine by monitoring its power usage when the cell is actually energized and actually ”running”.

I realize that the call will overall be using less power because the low temp sensor might not allow it to run. I’m asking specifically about power usage during the chlorine generation phase. Thanks.

i guess the first question I should have asked is this: Does the cell produce less chlorine in cold water because it is turned off by temp sensors (I am new to SWGs), or does it produce less because it doesn’t produce as much at low temps, or both?

 

[woodyp]

Let me get this straight....or as straight as I can understand it@

My cell worked just fine down to a hard limit of 50 degree water then stopped. Are y'all saying it is detrimental to cell life just to have power on to it even when not producing? I thought shutvdown was shut down.

 

[Newdude]

My cell worked just fine down to a hard limit of 50 degree water then stopped.

It probably lost efficiency when it was close to shutting off, which went unnoticed as UV demand was low. Put another way, the cell made half (?) as much as it should have, but you didn't even know.

So the discussion is about losing those few hours from the life of the cell. If it produced at full strength you could have run it less towards the end.

(IMO, that 'less' or whatever you lost is peanuts)