Is there a rule on how long or what % to run the SWG to adjust levels?

Skenn81 · May 17, 2022

I have the Pool Math app but unlike back when I didn't have the SWG and was just running liquid chlorine I can't figure out how much I am supposed to run the thing. Right now the pump is going from 7 in the morning to 3 in the afternoon, SWG at 100%. After a week of this the CL levels in the pool are up to 8. Liquid was easy, add this exact amount to raise points by as much as I need and it did it's thing. This one I am always randomly either changing the time it runs or futzing with the % because I dont know what I am doing.

The PoolMath app says the generator makes 1 per hour at 100% but I am not sure what that means. I end up just changing the hours or the percentages blindly to try to adjust it. For example I went out there this morning and set it to run 2 less hours a day because I need the numbers to go down so reduced the run time not really having much reasoning to the amount other than 2 hours seems like a good start.

Am I missing something here?

Newdude · May 17, 2022

Hey Skenn !!!! Let's start over from scratch.

Your IC30 with 16k gallons will make 7.5 FC per 24 hours on. The unit is either on or off. 24 hours at 50% is the same as 12 hours at 100%. Or any maths in between that are equal. 8 hours at 100% is 1/3 of the day, or 2.5 FC

It's not the peak season yet so you are running 8 hours instead of 12 and overproducing a little. It will likely fix itself very soon. Whenever you are given the choice of being under/over, choose to overproduce a little because you have leeway all the way up to SLAM FC. If the FC starts climbing more than a couple over target range, then reduce the runtime or % by a little and reevaluate the next day. That part takes some trial and error to become one with your system, but you'll get there.

I was too lazy to fiddle with it all the time. I let it run hot. If I caught the FC in the teens, I'd turn it off for a day or two and let it start building again.

Bperry · May 17, 2022

I’ve got mine setup so that if it starts getting too high, I punch the % down a notch and give it a few days. If it’s still going up, I bump it down again until I see it starting to decrease over time. Then when it gets close to my minimum comfort level I bump it up again. Don’t go chasing exact numbers for FC, just keep it above the minimum and somewhere close to the target. If it goes over or under that by 1-2ppm, no big deal.

ajw22 · May 17, 2022

Skenn81 said:
The PoolMath app says the generator makes 1 per hour at 100% but I am not sure what that means.

Let's talk about what that means.

The 1 is lb of chlorine per DAY if run at 100% for 24 hours. We really don't directly care about that number as much as we do how much parts per million (PPM) of chlorineit adds to your pool.

Your iChlor 30 will generate 0.3 ppm of FC per HOUR if run at 100% in your pool.

A typical pool in Florida needs 3 - 4 ppm of chlorine per day.

You can adjust the % generation or the hours your SWG runs to get the 3 to 4 ppm per day you need.

Running 100% for 10 hours ia about your minimum run time to give you 3 ppm of FC. Or 40% for 24 hours. Or anywhere in between those settings.

What is your CYA level?

poolurker5 · May 17, 2022

I was scratching my head on adjusting the Universal 40 (I oversized the swg 4x as I am running on a newish single speed pump), then I found out the swg duty cycle is a percentage of 3 hour increments. i am now running fine by splitting up my runtime into 3x of 2-hour chunks (on a mechanical intermatic) so I can spread out my skimming and have minimal pump time, with plenty of leeway in further adjustments. I try to keep fc at 7.

TexEdmond · May 17, 2022

Skenn81 said:
I have the Pool Math app but unlike back when I didn't have the SWG and was just running liquid chlorine I can't figure out how much I am supposed to run the thing. Right now the pump is going from 7 in the morning to 3 in the afternoon, SWG at 100%. After a week of this the CL levels in the pool are up to 8. Liquid was easy, add this exact amount to raise points by as much as I need and it did it's thing. This one I am always randomly either changing the time it runs or futzing with the % because I dont know what I am doing.

The PoolMath app says the generator makes 1 per hour at 100% but I am not sure what that means. I end up just changing the hours or the percentages blindly to try to adjust it. For example I went out there this morning and set it to run 2 less hours a day because I need the numbers to go down so reduced the run time not really having much reasoning to the amount other than 2 hours seems like a good start.

Am I missing something here?

If you're running the SWG at 100%, there's only one variable to change: runtime. I see you have a variable speed pump, but do you also have the ability to schedule a lower pump RPM for most of the day and then kick that up for skimming? Many folks here just run their VSP 24/7 so they've got constant water flowing across the SWG, and can run the percentage much lower.

Try looking at this calculator: SWG Run Time Calculator

I found it helps to look at the percentage runtime from a slightly different perspective in order for it to click in my brain. I'm also one of those who choose to run 3-4ppm higher than the minimum for my CYA level... since the chlorine is "free" there's no need for me to raise my blood pressure by driving so close to the cliff... Anything up to SLAM levels is safe to swim, so like has already been said, if it gets up above 10PPM that means I'm not able to do a regular pH test, so I'll turn it off and let the numbers drift back down. It's not as immediately obvious as manually glugging bleach into the pool, ya gotta just sortof feel it out.

Skenn81 · May 18, 2022

I forgot to turn on notifications for this post so have missed out.

CYA is at 70, so that sets the FC at 5 according to the chart.

For runtimes and RPMs, yes, I have the pump set to run for 2 hours high RPM to move the cleaner around and the rest of it has it turned down to 1300rpms, which was the lowest I was able to set it to be able to have the SWG flow sensor remain green.

Your iChlor 30 will generate 0.3 ppm of FC per HOUR if run at 100% in your pool.

A typical pool in Florida needs 3 - 4 ppm of chlorine per day.

Okay, so needing 3-4 ppm of CL a day, how does that relate to my target being a 5? Does the 3-4 keep it at 5 or does this add on to what's in there? I don't quite understand the relationship. It's because I have been doing liquid for so long I cant figure this out. Producing .3ppm of FC an hour, is there any relation to this number to what I used to do of pour in 24oz of bleach from a measuring cup kind of thing?

Your IC30 with 16k gallons will make 7.5 FC per 24 hours on.

Where did you get that total day figure? When you say it makes 7.5 FC per 24 hours, does that mean if the pool was at 0 at the end of the day it would be at 7.5, and then for example, if I lost 3 ppm and it was at 4.5, the next 24 hours it would be at 11.5, and go from there?

So it.s adding 7.5 into the pool and the pool is losing x ppm a day because of sun and everything else, so its end of day value + 7.5ppm for each 24 hour cycle?

It's not the peak season yet so you are running 8 hours instead of 12 and overproducing a little.

True, I also did not have the SWG last summer, it was installed at the end of the season after the pool was replastered, I did liquid all summer long before the pool was drained, I am still living like I was when adding liquid so this is my year to readjust to the new way of doing things.

Try looking at this calculator: SWG Run Time Calculator

Do I need a dropbox account to download that?

Newdude · May 18, 2022

Skenn81 said:
CYA is at 70, so that sets the FC at 5 according to the chart.

Correct.

Skenn81 said:
Okay, so needing 3-4 ppm of CL a day, how does that relate to my target being a 5?

Welp. Here is where it gets tricky and we will hatch a plan for how you run. We will use the chart in ways it makes sense for you, and stray a bit where it doesn't. You have 3 options.

1) produce only at night for possibly cheaper electric costs for the pump. (If applicable) This makes a daytime swing closer to a LC pool and you will plan similar to how you used to do it. Predose tomorrow's loss overnight, to remain above minimum tomorrow evening when you start producing again. You will aim to start each day 3-4 ppm above the reccomended 5.

2) run 24/7 and swing half as much as a LC pool because you are adding a chunk of the FC lost during the day, and only have to make up the difference overnight. Split the difference and aim to start the day 1-2 over the 5. You will have some wiggle room if you happen to fall to 4 at any point and it will be a 5 again in a few hours.

3) produce only during the day and be producing as you lose, more or less keeping the 5 as a constant. It might swing 4-6 at times, but you are covered either way.

ajw22 · May 18, 2022

Skenn81 said:
I forgot to turn on notifications for this post so have missed outOkay, so needing 3-4 ppm of CL a day, how does that relate to my target being a 5? Does the 3-4 keep it at 5 or does this add on to what's in there?

The suns UV rays consume 3-4 ppm of FC per day. If you add 3-4 ppm of chlorine using liquid chlorine or using the SWG your FC should stay round 5.

If you don't add any FC every day your FC will NOT stay at 5.

Skenn81 said:
Producing .3ppm of FC an hour, is there any relation to this number to what I used to do of pour in 24oz of bleach from a measuring cup kind of thing?

6 oz of 10% bleach is 0.3 ppm. So running your SWG for an hour is the same as adding 6 oz of bleach.

Since you know your pool would need 24 oz of bleash, that would be four 6 oz doses.

Your SWG is doesing in the same way and will require 4 hours. When you say it makes 7.5 FC per 24 hours, does that mean

if the pool was at 0 at the end of the day it would be at 7.5, and then for example, if I lost 3 ppm and it was at 4.5, the next 24 hours it would be at 11.5, and go from there?

Yes.

Skenn81 said:
So it.s adding 7.5 into the pool and the pool is losing x ppm a day because of sun and everything else, so its end of day value + 7.5ppm for each 24 hour cycle?

Yes.

Skenn81 · May 18, 2022

I am starting to understand how it all works...

Okay so with those two responses, .3 an hour so thats 10 hours is 3 on the test scale, what everyone said of Florida pools use / need 3 to 4 ppm a day, so that's where the 10 to I guess 13 hours are needed of runtime. So if I want 5 I somehow get it to 5 and then it will lose 3 a day so I need 10 hours at .3 an hour to make up for that loss?

In the app it says "24 Hour SWG Output: 1"

What is that 1 mean if here we are talking about .3 an hour? That's back to the 7.5 that was mentioned.

When checking the FC level when running an SWG, when are you supposed to do that? Do I check when it's running or when it's done? I havent been checking when it's running because I thought there would be a higher chance of a false reading if it's pumping out fresh CL into the pool when collecting my sample.

Bperry · May 18, 2022

Skenn81 said:
I am starting to understand how it all works...

Okay so with those two responses, .3 an hour so thats 10 hours is 3 on the test scale, what everyone said of Florida pools use / need 3 to 4 ppm a day, so that's where the 10 to I guess 13 hours are needed of runtime. So if I want 5 I somehow get it to 5 and then it will lose 3 a day so I need 10 hours at .3 an hour to make up for that loss?

In the app it says "24 Hour SWG Output: 1"

What is that 1 mean if here we are talking about .3 an hour? That's back to the 7.5 that was mentioned.

When checking the FC level when running an SWG, when are you supposed to do that? Do I check when it's running or when it's done? I havent been checking when it's running because I thought there would be a higher chance of a false reading if it's pumping out fresh CL into the pool when collecting my sample.

It’s just my opinion, but you’re thinking too hard. Just turn the thing on and test a while later. If the FC gets too high, turn it down a bit. If it starts getting too low, turn it up. Once you start doing math and all that it stops becoming “trouble free”.

Same thing with liquid chlorine, just add a gurgle or two if the FC is low. Once you start measuring it out in ounces it’s too much hassle. Unless you like all that stuff and enjoy it, then it’s ok.

Newdude · May 18, 2022

Skenn81 said:
Okay so with those two responses, .3 an hour so thats 10 hours is 3 on the test scale, what everyone said of Florida pools use / need 3 to 4 ppm a day, so that's where the 10 to I guess 13 hours are needed of runtime.

Correct. And it fluctuates from low in the early/late season to peaking in the middle of the summer. You adjust every couple of weeks to match the ever changing UV loss, just like with LC.

Skenn81 said:
In the app it says "24 Hour SWG Output: 1"

1 lb of chlorone gas produced per 24 hours on. That goes into poolmath to calculate how many FC that makes a day for your sized pool. Pool math really is the best friend that doesnt care how many times you cheat off her.

Skenn81 said:
What is that 1 mean if here we are talking about .3 an hour? That's back to the 7.5 that was mentioned.

1/24 of 1 lb per day creates .3 FC per hour for your pool. You only need to do the calc once. Now just use .3 FC per hour.

Skenn81 said:
When checking the FC level when running an SWG, when are you supposed to do that?

Once a day, however you prefer. Some like AM to be sure they are ahead today. Other like PM to know they made it through the day ok and will be prepared for tomorrow. Tahmayto Tahmahto. It's all good.

Skenn81 said:
Do I check when it's running or when it's done?

Up to you. Pick a spot away from a return and that water will be about as mixed as it's gonna get.

Skenn81 said:
I havent been checking when it's running because I thought there would be a higher chance of a false reading if it's pumping out fresh CL into the pool when collecting my sample.

Only if you're doing it near a return.

Skenn81 · May 19, 2022

Once you start measuring it out in ounces it’s too much hassle. Unless you like all that stuff and enjoy it, then it’s ok.

You should see how many spreadsheets I have.. this is what makes it fun for me.

Newdude said:
1/24 of 1 lb per day creates .3 FC per hour for your pool. You only need to do the calc once. Now just use .3 FC per hour.

How did you figure this part out / where can I go to see it? I want to try a few other pool measurements then and see how it all works.

That .3 is the part that has me much less confused now. .3 an hour going at 100% means I can understand what I would need to do. Too high? Reduce by .3 an hour or by %, and same with when I need to raise it up. If its off by 1 or 2 points then it would be 3 to 6 hours of run time?

Essentially you run it much longer to get it up to where you need to go, like from 0 to 5 the first few days, and then maintain at .3 an hour with a 3 to 4 loss per day and then extra for actually using the pool. So the 12 hours a day gives me 3.6 like mentioned and that would be in the middle of the the typical 3 to 4 loss from the sun in Florida.

I think this is starting to come together now. Not having that .3 number really threw me into the confusion.

Newdude · May 19, 2022

Skenn81 said:
How did you figure this part out / where can I go to see it? I want to try a few other pool measurements then and see how it all works.

Click on the magnifying glass on the FC page and it pulls up the output of many SWGs for reference. Yours says 1 lb of chlorone gas per 24 hours. Put that into the correct box as your add and it will make 7.2 FC per day at 100% or .3 an hour. (I didn't do my own calc for you, assuming they did up top)

Skenn81 said:
That .3 is the part that has me much less confused now. .3 an hour going at 100% means I can understand what I would need to do. Too high? Reduce by .3 an hour or by %, and same with when I need to raise it up. If its off by 1 or 2 points then it would be 3 to 6 hours of run time?

Correct. You really can't measure .3 FC, or even .5FC reliably. Just use the whole #s when adjusting run time. Let's say you wanted 1 less FC, then cut 3 hours of 100% runtime. Or any maths between runtime and % to get the same result. Cut 6 hours at 50%, for example, for the same 1FC. Or add just the same if you're looking to increase.

Skenn81 said:
Essentially you run it much longer to get it up to where you need to go, like from 0 to 5 the first few days,

Yes. But that leaves you short for several days so you spike it with LC to start, and 15 mins later, maintain the level you wanted.

In your case with a large unit, it would take less tha a day at 7.2 FC per day, but still. Alot can happen while you are low.

Anytime the adjustment needs a spike, use LC. If you are 1 FC low, but still plenty clear from minimum, then it's OK to let the unit handle it.

Skenn81 said:
and then maintain at .3 an hour with a 3 to 4 loss per day and then extra for actually using the pool. So the 12 hours a day gives me 3.6 like mentioned and that would be in the middle of the the typical 3 to 4 loss from the sun in Florida.

Bingo. You test regularly to see if this part of the season is increasing the UV loss as it warms up, or decreasing the daily demand for the back half of the season. Day to day you won't notice any change. Week to week you'll see it eventually. Always overshoot a little when learning. This time of year you underproduce when you miss an adjustment, and get in trouble quick. The back half of the season gives you too much production anytime you miss the adjustment time. That's a great time to 'mess up' as no harm is done.

Skenn81 · May 19, 2022

Ah ha. In the Pool Math app I entered current CL of 0 and 7.2 for the target and there it is, says to run for about 24 hours to do that. Divide the 7.2 by the 24 and there is the .3.

Math makes it all clear! The numbers have been in front of me the whole time, lacking the understanding on how to interpret them led to this confusion. So now I think I get it, adjust up or down based on the .3 and I should be good to go.

Thanks to everyone for explaining all of this.

Newdude · May 19, 2022

Skenn81 said:
Ah ha. In the Pool Math app I entered current CL of 0 and 7.2 for the target and there it is, says to run for about 24 hours to do that. Divide the 7.2 by the 24 and there is the .3

It's a bunch to process at first just like the ABCs. It's equally as stupid simple, but it takes a minute.

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Is there a rule on how long or what % to run the SWG to adjust levels?

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