Whats a more efficient way to run a SWG cell

mac4lyfe

LifeTime Supporter
Jun 8, 2007
212
Houston, Texas
#1
Recently added SWG and I'm wondering if it's more efficient (easier on the cell) to run the cell 24 hours a day at 50% or 12 hours/day at 100%? It seems to me that it would be the same but maybe someone else knows better.

Also with the superchlorinate function it also seems that even though it has a higher use that depending on how often you run it in that mode that if you run it for a shorter time period that it would use up the cell just the same. What I'm saying is that if superchlorinate runs at a higher rate it also has a higher FC output which means you could use it less per day and it should be fairly equal to running longer at a lower output.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#2
It doesn't matter, the cell lifetime is in hours turned on. You get the same hours turned on with 24 hours a day at 50% and 12 hours/day at 100%.

Superchlorinate is the same as changing the percentage to 100% for 24 hours (or however long your unit stays in that mode).
 

Matt

Well-known member
Jun 4, 2008
126
#3
Also, SWG's do not run at anything but 100%. They are either running and producing chlorine, or they are doing nothing. When you set it to 50%, it runs for half of the time. i.e. It might run 10 minutes, then go off 10 minutes, then on, then off, etc. I don't know the exact timing or how it decides. So either way, your SWG is running at 100% for the same amount of time, it's just a matter of when it does.

I run mine at 10-30% and it never has trouble keeping up. I suspect this is because I'm in New England and we don't get really hot direct sun. I keep my pump on 12 hours a day, so basically the SWG runs anywhere from 1.2 hours to 3.6 hours per day.
 

Strannik

TFP Expert
LifeTime Supporter
Jul 24, 2007
874
Brisbane, Australia
#4
Matt said:
Also, SWG's do not run at anything but 100%. They are either running and producing chlorine, or they are doing nothing. When you set it to 50%, it runs for half of the time. i.e. It might run 10 minutes, then go off 10 minutes, then on, then off, etc. I don't know the exact timing or how it decides. So either way, your SWG is running at 100% for the same amount of time, it's just a matter of when it does.
It depends on SWG. Our SM models run the way you describe it, however AC and RP actually run on reduced output rather than time proportion. Our commercial models also regulate the output, rather than run 100% full on.
 

stever

LifeTime Supporter
#5
To preserve the life of the cell -- seriously think about 'superchlorinating' or shocking the pool in the traditional 'add chemicals' way. This will also get the shock up to strength almost immediately instead of over 24 hours and should work better.
 

Matt

Well-known member
Jun 4, 2008
126
#6
Thanks for that info, all the ones I looked at were 100/0 and did it by altering when they ran.

I wonder if there is any advantage to either. The time based versions would run for less time, but at greater power.
 

Strannik

TFP Expert
LifeTime Supporter
Jul 24, 2007
874
Brisbane, Australia
#7
I'd say it's more beneficial to run constantly on lower power, because the most damaging time to the anode is when it's switched on. And with our large commercial systems it's definitely better to run them 24/7 at lower output, because it provides constant sanitation, which is important when you have 1000 of people swimming in your pool.
 

Matt

Well-known member
Jun 4, 2008
126
#8
Yeah, definitely agree on the point that constant sanitation is important. I run my pump during the day, so my SWG runs then too, since that is when I'm most likely to be losing chlorine. This way it helps maintain a steady state (ideally) with the amount of chlorine lost to the sun being roughly equal to that that is being produced by the SWG.
 

mac4lyfe

LifeTime Supporter
Jun 8, 2007
212
Houston, Texas
#9
Man, too many choices and I'm not sure which is best. What do you guys suggest I do?I normally run my pump 6 - 8 hours a day which recircs the pool at least once. Since I've added the SWG, I've run the pump 24/7 and put the Hayward Swimpure plus on 50% which seems to keep my FC level fairly constant. Should I maybe go to 12 hours of pump time and bump the SWG to 100%? Is 100% and Superchlorinate the same thing for my unit?

BTW: I'm in Houston where we get much sun. Should I run the SWG during the day while the sun is brightest or run at night and make up the FC loss during the day?

Also Strannik if you say that the switching on and off of the unit does the most damage to the cell then I would think that I shouldn't use any setting but 100% or Superchlorinate if my unit shuts off and on at lower %. I know too many questions but I'm trying to get a better understanding.
 

Matt

Well-known member
Jun 4, 2008
126
#10
What's your cyanuric acid level at? I'm surprised you have to push the SWG that hard, but maybe it's because you are in Houston, and I'm in New England...

Also I run my pump 12 hours/day usually. I like to have it running when people are in the pool.

I think it's better to run it during the day so that your sanitizer levels don't drop during the day. If you run it only at night, they'll drop during the day, possibly too low. If it's off at night, your sanitizer levels shouldn't drop much because there is no sun.
 
G
#11
Residential units are made to cycle on and off. Some, like the PoolPilot also offer different power levels (but this unit still cycles on and off). A general recommendation is 8-12 hours pump run time and output (and power level if available) adjusted to maintain FC at 3-5 ppm. This is assuming that your CYA is within the recommended range (usually 60-80 ppm). Don't fall into the trap of trying to run a salt pool with too low a CYA. It has many negative effects. You can read the sticky on water balance for SWGs for more info on that topic.
 

mac4lyfe

LifeTime Supporter
Jun 8, 2007
212
Houston, Texas
#12
My CYA is at 75ppm so no problem there. I'm still running the pump and SWG 24/7 until I can figure out a good balance. My FC seems to be around 5ppm in early morning and dips to 3.5 at sunset. This is with daily swimmer load. When I superchlorinated one evening it bumped up to 7 ppm that morning.

The SWG obviously can't keep up with my FC loss during the day at 50%. Do you think I should superchlorinate during the day so that there's no FC loss.?

Also how much PH drift should I see? Or better question, how long will it take for my PH to rise (currently at 7.5) since I'm running a SWG? Does it take several days or a few weeks for the PH to drift up higner?
My Alkalinity - 100ppm
CH - 285
Phospate - 300ppb
Salt - 3200ppm
Copper, Iron, TDS all 0
 

SeanB

TFP Expert
Platinum Supporter
LifeTime Supporter
#13
I run my pump / swg almost entirely at night. That way the full strength of the chlorine is being used to sanitize the water rather than being consumed by the sun.

I run it just a couple of hours in the early morning along with the pool cleaner to get any debris that may have fallen in over night. Otherwise, I run the pump anytime people are swimming and after dusk for the other 8 hours.
 

Matt

Well-known member
Jun 4, 2008
126
#14
I find that I have to continually adjust my SWG. I have an ecomatic, and the settings allow me to set any percentage between 0 and 100 on a dial. I have found so far this year that 10-30% works well, depending on sun levels. This maintains my level around 6 ppm usually. The key though is that I need to keep changing it. Sometimes it creeps up one day, so when I test it, I turn it down lower for the next day to bring it back to where I want. Then again, I suppose in Houston you have only one kind of weather... very hot and sunny. New England is not like that...

The higher you run the SWG, the more pH creep you are likely to see. Also, if you try to force it to a lower pH, it will creep up faster, while if you keep it closer to the middle or higher end, it won't creep up as much. With good TA (70-80) and a borate buffer, some people find they get almost no pH creep.

Personally, I get lots, and just dump lots of acid in to drop the pH low again, but that is probably not the optimum way to maintain your pool. Acid is cheap though, so I don't really mind. Every pool is different though. There's no easy way to describe how much your pH will change. However, I can say that running the SWG more will increase the pH more.

If I were you I'd try to find the approximate value that will make the output of the SWG equal the loss from sunlight and bather load during an average day, and run it there during daylight hours. I prefer to keep my sanitizer levels stable. However, Sean's suggestion is also valid, in that his will allow for a lower total production of chlorine (due to it having longer to work before the sun hits), less wear on the SWG, and less pH creep... but at the expense of declining sanitizer levels during the day. It's up to you to decide what is more important to you.
 

Strannik

TFP Expert
LifeTime Supporter
Jul 24, 2007
874
Brisbane, Australia
#15
waterbear said:
Residential units are made to cycle on and off.
As i said, not all of them :)
Our AC and RP Series actually adjust the voltage applied to the cell, rather than run at 100% all the time.

Bottom line - the lifetime of the cell comes down to the quality and type of anode material used. It is usually rated in Amps/sq. m, so if the manufacturer used higher rated anode material it will last longer. N ow since no manufacturer I know of publishes those figures, you really have no way of knowing if maximum setting of SWG equals to maximum rating of the anode material.

For example:

Cell A and cell B both have maximum rating of 25A.
However anode material in cell A is rated for 300A/sq. m. and anode material in cell B is rated for 600A/sq.m.

Clearly that cell B will last longer if both are operated at 100%.

This is why we offer to our clients optional upgrade to commercial grade anode material on residential cells.

The difference in quality of anode material between manufacturers is quite dramatic. I might post a graph of comparison of our anode material with others a bit later (i won't name the manufacturers for obvious reasons).
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#17
You want to adjust the percentage so that the FC level in the early evening is appropriate for your CYA level. With a SWG and CYA at 75, you want FC to be at least 3 at all times. So your levels are fine. Personally I would turn it up just a little to have more margin for unusual events, but that isn't required if you are paying attention.

The fact that the FC level is higher in the morning and lower in the evening is normal. If you run your pump only during the day you can actually save a little chlorine/electricity, but it isn't a big deal. If you have time of day electric rates it is well worth it to only run your pump at night.

A SWG in an outdoor pool is fairly stable, you can have the percentage a little too high or a little too low and everything will still be fine. If you enjoy adjusting the percentage every day based on todays FC level then go for it, but it really isn't required or worth much besides entertainment value. The improvement you can get out of fine tuning the percentage vs the FC level or the pump run time vs the percentage is tiny and not worth worrying about.

There are far more important reasons to adjust your pump run time then minor optimizations of the SWG efficiency or cell life time. The pump needs to be run enough to keep the pool clean. Any longer than that and you are wasting significant amounts of electricity. Both of those factors are far more important than anything to do with the SWG. The only exception is if the SWG is already at 100% and you aren't getting enough chlorine and you know it isn't algae. Then you will need to increase the pump run time to be able to get more chlorine from the SWG. Other than that don't worry about it.