PWM SWGs (Circupool 4th gens) and CYA

[cmc0619]

From here, @chem geek said a long time ago the following:
Salt Water chlorine Generation (SWG) pools seem to require a higher level of CYA, about 70-80 ppm, to operate efficiently. The theory is that the CYA is slow to "store" the chlorine as it is being generated so without enough CYA there is a build-up of chlorine that degrades the performance of the salt cell. I would prefer that the SWG manufacturers offer a larger lower-power (per length) cell that would work efficiently at lower CYA concentrations.

Given this research from Rattus Suffocatus in reference to the CircuPool EDGEs
"
"The CircuPool EDGE-40 electronic chlorine generator is an advanced, fourth-generation salt pool system.......The CircuPool EDGE-40 salt system features streamlined modern design and the latest technology to provide worry-free operation - you'll always know its working thanks to its exclusive edge status lighting. Its digital switch-mode power supply automatically accepts 110V or 220V, making it easy to connect to your existing pump timer or controls. "

Digital switch mode supply by definition means a variable pulse width modulated supply. So with a constant draw like you see the cell is on all the time at a lower power level.
"

Does this mean that I don't need to run this particular brand of SWG at the typical SWGs levels? How would I test this?

 

[Jimrahbe]

cmc,

What gives you the idea that high FC " degrades the performance of the salt cell." That is just not true at all..

Lower CYA will allow the sun to burn off more FC and require you to keep a higher target FC..

This has nothing to do with the power supply driving the SWCG. SWCGs operate off of DC volts..

I guess I don't fully understand the problem.

Thanks,

Jim R.

 

[cmc0619]

Those aren't my words. They're from ChemGeeks post. I'm not talking about keeping an unmeasurable CYA just a CYA level that's more in line with non-SWG pools.

The power supply driving the EDGE uses PWM on the DC side to modulate the DC power to the cell. It doesn't operate like a normal SWG. It runs constantly at lower power. Just like what Chemgeek said he'd prefer to see in his post. So I'm wondering if that means the guidelines should be amended for this particular type of SWG

 

[Flying Tivo]

You should still use the same guidelines. It doesnt matter how the swg is driven by the power supply, its about how much Chlorine the SWG produces.

 

[Jimrahbe]

C,

Some Australian cells do that.. Their % of output changes the actual amount of chlorine made.. Where the American cells always produce the same amount of chlorine, but the % of output controls how long the cell runs each hour.

But.. sorry to be dense, but I still can't grasp the problem.. If your pool uses 3 ppm of FC per day, then it seems like either type of cell still has to produce 3 ppm of FC? Seems to me, in the big picture you are still going to use the same amount of power to generate the same amount of FC.

Thanks,

Jim R.

 

[cmc0619]

C,

Some Australian cells do that.. Their % of output changes the actual amount of chlorine made.. Where the American cells always produce the same amount of chlorine, but the % of output controls how long the cell runs each hour.

But.. sorry to be dense, but I still can't grasp the problem.. If your pool uses 3 ppm of FC per day, then it seems like either type of cell still has to produce 3 ppm of FC? Seems to me, in the big picture you are still going to use the same amount of power to generate the same amount of FC.

Thanks,

Jim R.

I'm not looking to solve a problem per se which is why I posted this in the Deep End. I'm just curious why I would keep my CYA levels at SWG recommended levels when Chemgeek made the statement (and I'm partially inferring here), that since I have a lower power slower infusion of Chlorine into my water stream I should be fine running at levels as if I were still pouring sodium hypochlorite into my pool the old fashioned way.

But to your point, if it's simply a matter of X amount of Chlorine in = Y amount of bad stuff gets sanitized, then why a different recommended CYA level for an SWG in the first place? The correct answer to that, I assume, is Chemgeeks statement above. He's like the godfather of TFP principals back in the early days right? Seems like a pretty good source of info so I'm taking what he says as gospel. Given that assumption. And given that my SWG doesn't operate like a more common unit, can I also take his statement that a PWM powered unit would be just as effective with a lower level of CYA.

 

[Jimrahbe]

C,

I did not notice your post was in the Deep End forum.. I am not near tall enough to stand in the deep end...

One thing I do know, that if you try to run a SWCG with a CYA of say 40, you will have to run the output at near 90 or 100% to keep up.

Good luck with your quest...

Jim R.

 

[cmc0619]

I did not notice your post was in the Deep End forum.. I am not near tall enough to stand in the deep end...

One thing I do know, that if you try to run a SWCG with a CYA of say 40, you will have to run the output at near 90 or 100% to keep up.

Actually, you've been very helpful! This is part of the info I was looking for. I will keep an eye on my FC and the power settings over time.

 

[mgtfp]

I am running one those Australian SWGs, and I seem to be fine with lower CYA levels without having to run the cell non-stop on full power. 8-10 hours on like 70-80% seem to be fine even around 50 ppm CYA where I live. But we didn't have too much sun this summer. There also was a lot of smoke haze in the air due to the bush fires. That was crazy, feels like half the country burnt down, but in Melbourne, just a few 100 km away from massive fires, it remained quite cool and wet. But we did get a lot of smoke.

And I run my SWG for big parts during times where I don't get direct sun on the pool. I tend to stay more in the non-SWG target FC range to have enough buffer while not running the cell during the sunny hours and when we actually use the pool and create chlorine demand.

There could also be an influence by running an old (very old) single speed pump (certainty don't want to run this 24/7). So, I always have high flow when running the cell, which means that my freshly generated chlorine might get diluted faster into my pool volume, making it less susceptible to UV attack.

But this was my first summer following TFP. Let's wait for next summer and collect more data.

Going with Jim's example of a chlorine demand of 3ppm per day, you need to consider that a non-SWG will have a similar demand. And they have no problem with a lower CYA. So there might be a valid point of a gentler SWG chlorine generation being more similar to a standard pool situation.

And I do remember Chemgeek's post that cmc0619 was referring to where he explained that higher CYA is required in an SWG pool so that the high FC from the cell doesn't get lost again straight away. So, a gentler FC generation might be beneficial. I'll have to reread the post, might not remember it correctly.

But then we might also lose the benefit of higher FC concentrations within the cell that allow for a lower target FC compared to non-SWG pools.

I am not trying to give any recommendations here for others, just thinking out loud and describing what seems to work for me. And the OP caught my attention since I was having similar thoughts about why I seem to be fine with standard pool CYA levels. I actually wasn't aware that US SWGs seem to follow a different mode of operation to Aussie ones. That might be a clue. Curious about other experiences from Oz.

Cheers,
mgtfp

 

[markayash]

The edge does work different, it’s on all the time and produces more chlorine as you increase power. My smart plug measures watts As I ask for more production watts go from around 40 to 210 and never shuts off.
Not saying it’s better or worse just different.
I have the Edge40

 

[cmc0619]

I am running one those Australian SWGs, and I seem to be fine with lower CYA levels without having to run the cell non-stop on full power. 8-10 hours on like 70-80% seem to be fine even around 50 ppm CYA where I live. But we didn't have too much sun this summer. There also was a lot of smoke haze in the air due to the bush fires. That was crazy, feels like half the country burnt down, but in Melbourne, just a few 100 km away from massive fires, it remained quite cool and wet. But we did get a lot of smoke.

And I run my SWG for big parts during times where I don't get direct sun on the pool. I tend to stay more in the non-SWG target FC range to have enough buffer while not running the cell during the sunny hours and when we actually use the pool and create chlorine demand.

There could also be an influence by running an old (very old) single speed pump (certainty don't want to run this 24/7). So, I always have high flow when running the cell, which means that my freshly generated chlorine might get diluted faster into my pool volume, making it less susceptible to UV attack.

But this was my first summer following TFP. Let's wait for next summer and collect more data.

Going with Jim's example of a chlorine demand of 3ppm per day, you need to consider that a non-SWG will have a similar demand. And they have no problem with a lower CYA. So there might be a valid point of a gentler SWG chlorine generation being more similar to a standard pool situation.

And I do remember Chemgeek's post that cmc0619 was referring to where he explained that higher CYA is required in an SWG pool so that the high FC from the cell doesn't get lost again straight away. So, a gentler FC generation might be beneficial. I'll have to reread the post, might not remember it correctly.

But then we might also lose the benefit of higher FC concentrations within the cell that allow for a lower target FC compared to non-SWG pools.

I am not trying to give any recommendations here for others, just thinking out loud and describing what seems to work for me. And the OP caught my attention since I was having similar thoughts about why I seem to be fine with standard pool CYA levels. I actually wasn't aware that US SWGs seem to follow a different mode of operation to Aussie ones. That might be a clue. Curious about other experiences from Oz.

Cheers,
Markus

Thank you for the data point! I provide a link to @chem geek's original post in the first post and quote him. You remember it correctly. I'm hoping the EDGE is the gentle FC generation he speaks of. My pool is surrounded by 50 ft tall oaks. The way the sun travels, I only get direct sunlight from about 2pm to sunset so keeping my FC at 40 is kind of what I'm trying to do. I feel like it makes testing less problematic because I can keep my FC levels < 10ppm

So that's another thing to consider I hadn't thought of. Should I be targeting the non-SWG target FC because, you're right, our SWGs don't have that super high FC concentration in the cell.

I appreciate your comments!

 

[cmc0619]

The edge does work different, it’s on all the time and produces more chlorine as you increase power. My smart plug measures watts As I ask for more production watts go from around 40 to 210 and never shuts off.
Not saying it’s better or worse just different.
I have the Edge40

EDGE40 here too. I just looked again, it was your thread on the EDGE40 that got me wondering about this. Good find!

 

[mguzzy]

This sounds like an easy (and fun) experiment to do.. I did this one summer with my SWG. I added CYA in incremental batches and watched what happened to my FC. Yeah, I was bored. Anyway it really did seem to have better retention when I went above 60 -70 range and then leveled off. I didn't take it it any higher than 80... then the seasonal rains diluted it all for me and I have a better idea of what CYA level works best for my SWG.

 

[markayash]

EDGE40 here too. I just looked again, it was your thread on the EDGE40 that got me wondering about this. Good find!

I actually emailed Circupool and asked if it worked different because it seemed to draw more or less power and was basically told “ don’t worry about it, it works”
In their defense I probably got a help desk type person but you think they would enjoy talking shop.

 

[mgtfp]

This sounds like an easy (and fun) experiment to do.. I did this one summer with my SWG. I added CYA in incremental batches and watched what happened to my FC. Yeah, I was bored. Anyway it really did seem to have better retention when I went above 60 -70 range and then leveled off. I didn't take it it any higher than 80... then the seasonal rains diluted it all for me and I have a better idea of what CYA level works best for my SWG.

I will certainly do this experiment next summer. This summer was more about getting the TFP method running, starting proper testing and data logging. Being at home since late summer certainly helped in understanding more about pool chemistry and doing more testing to understand how the chemical levels change over the course of a day or a week. Next summer, I will try to be more precise, measure the influence of sunshine duration , CYA levels etc. We'll see.

 

[mguzzy]

I was wondering how your response ended up in the other thread...
The mysteries of modern electrons never cease to amaze me.

(You can leave it here and there! woo hoo!)

 

[cmc0619]

I actually emailed Circupool and asked if it worked different because it seemed to draw more or less power and was basically told “ don’t worry about it, it works”
In their defense I probably got a help desk type person but you think they would enjoy talking shop.

Sadly, I've found that people who truly enjoy what they do are far and few. Luckily, as network engineers, we don't have that problem!

 

[mgtfp]

... Yep, and then, after copying it to the correct thread, I first edited the wrong one again with my note to an admin to delete the post in the other thread. Hope it's all in the right place now. Switched to my laptop now, much easier than on the phone.

 

[cmc0619]

This sounds like an easy (and fun) experiment to do.. I did this one summer with my SWG. I added CYA in incremental batches and watched what happened to my FC. Yeah, I was bored. Anyway it really did seem to have better retention when I went above 60 -70 range and then leveled off. I didn't take it it any higher than 80... then the seasonal rains diluted it all for me and I have a better idea of what CYA level works best for my SWG.

Well I'm definately bored!

And just for anyone who comes along this thread and thinks I'm trying to change the methods of TFP as a whole, I'm certainly not and wouldn't dare. I'm just curious about this corner case for the few of us (well, and all of Austrailia) with the PWM SWGs and how it might be different for us, if at all.

 

[mgtfp]

Well I'm definately bored!

And just for anyone who comes along this thread and thinks I'm trying to change the methods of TFP as a whole, I'm certainly not and wouldn't dare. I'm just curious about this corner case for the few of us (well, and all of Austrailia) with the PWM SWGs and how it might be different for us, if at all.

Certainly a good opportunity now to run some extended testing with all this time spent at home. I'll have to wait for the next Aussie summer, when I might not be at home as much anymore. And I fully agree with you, I certainly don't want to change anything in the TFP method, it is great as it is. But it can't hurt to collect some data to understand better which process window works best under our boundary conditions (duration of sunshine, tree environment, type of SWG, pump flow, etc).