# SWG Run Time Calculator

#### flipr

Re: Formula for SWG / Pump Runtime?

I was just going to post a thread asking if my math was right, as I'm trying to determine the same thing. My Pentair IC40 is standalone, and my choices are only 20%, 40%, 60%, 80%, or short-term 100% for 24 hours.

I converted output to ounces/hour, then gallons of pool *8#/gal *16 to get to ounces, figured how many 'millions parts' of water I had, then factored *4 to get to my 'needed' 4ppm daily increase to offset sun and bather load. Divided by my percentage production per hour to get a starting point.

Like others, I had been told about 8 hours a day at 40% should work fine, until I got a mild algae bloom and had a 2 week slam.

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Thank you. A ballpark is what I was looking for. It would at least shorten the trial and error. Ones i got the formula working, it instantly helped me realize I why it "was not keeping up". It just was not running enough. Mmn The

Probably need to document a process to calculate the daily FC PPM loss.
I'm coming off a slam, so I've been losing 3-3.5/day due to sun, when I had the SWG unplugged. Much harder when SWG is running and hitting a moving target.

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nm
Excellent work.

#### JoyfulNoise

TFP Expert
Platinum Supporter
Re: Formula for SWG / Pump Runtime?

Hopefully you all are using Pool Math to convert ounces of chlorine gas into FC when you calculate ppm (use the "Effects of Adding Chemicals" section).

Remember that an SWG is rated in pounds of chlorine gas (Cl2) per day. But 1 mol of chlorine gas, when dissolved in water, splits in half and converts into 1 mol of hypochlorous acid (HOCl) and 1 mol of chloride ion (Cl-). So if your just using a ratio of ounces of chlorine gas to ounces of pool water, your calculations are going to be off by a factor of 2. Using Pool Math simplifies the calculations by converting ounces of chlorine gas into FC in water and so takes into account the detailed chemistry.

#### flipr

Re: Formula for SWG / Pump Runtime?

Hopefully you all are using Pool Math to convert ounces of chlorine gas into FC when you calculate ppm (use the "Effects of Adding Chemicals" section).

Remember that an SWG is rated in pounds of chlorine gas (Cl2) per day. But 1 mol of chlorine gas, when dissolved in water, splits in half and converts into 1 mol of hypochlorous acid (HOCl) and 1 mol of chloride ion (Cl-). So if your just using a ratio of ounces of chlorine gas to ounces of pool water, your calculations are going to be off by a factor of 2. Using Pool Math simplifies the calculations by converting ounces of chlorine gas into FC in water and so takes into account the detailed chemistry.
Thanks for your comment, my manual just said 1.4#/day of 'pure chlorine', wasn't even thinking about a conversion for gas to solution. Since it was expressed in pounds, I was trying to equate to ppm.
Appreciate the catch.

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

Hopefully you all are using Pool Math to convert ounces of chlorine gas into FC when you calculate ppm (use the "Effects of Adding Chemicals" section).

Remember that an SWG is rated in pounds of chlorine gas (Cl2) per day. But 1 mol of chlorine gas, when dissolved in water, splits in half and converts into 1 mol of hypochlorous acid (HOCl) and 1 mol of chloride ion (Cl-). So if your just using a ratio of ounces of chlorine gas to ounces of pool water, your calculations are going to be off by a factor of 2. Using Pool Math simplifies the calculations by converting ounces of chlorine gas into FC in water and so takes into account the detailed chemistry.
The calculation in the tool does the conversion. If you enter 16oz in Pool Math for 12,000 gallons for chlorine gas, it will result in raising the FC by 10, so will the calculator. In the calculator, I used lbs and then divide by 16 to convert to oz as is used in Pool Math. I did this since the SWGs document the free chlorine they provide in pounds and thus makes it easier for the user. Feel free to test it out though, that is why it is "Beta".

#### JoyfulNoise

TFP Expert
Platinum Supporter
Re: Formula for SWG / Pump Runtime?

Ack, my mistake

The output is listed as equivalent pounds of chlorine gas from the cell (same as units of FC) and I neglected to take into account a chloride ion on one side of the electrochemical equation, my bad. Serves me right for trying to look things up on a mobile phone.

No worries then, the beta version seems to check out. Always good to double-check these things.

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

Ack, my mistake

Always good to double-check these things.
Agreed. I work in software with alot smarter colleagues than me and they make mistakes too. That is why we have numerous colleagues in QA department and hundreds of thousands of automated tests.

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By the way, thanks for checking on it!!!!

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

Updated calculator to include SWG Run Time Chart. This chart shows all run times using the SWG Output and FC Demand of 1 to 5.

#### flipr

Re: Formula for SWG / Pump Runtime?

Matt, my results don't make sense. Says at 40% to run for 13.7, then the chart says 100% for 13.7 hours. I thought the chart would show all the various options, but it doesn't show all the choices.
So I'm not sure what I get in the chart, as it seems to contradict the initial calculation

My 2 cents

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

Flipr, thanks for noticing the issue. It has been fixed. The Calculator was working fine but the new Chart was definitely not right. I reset the formula for that.

#### kcindc

Gold Supporter
TFP Guide
Re: Formula for SWG / Pump Runtime?

I can't seem to find the link to the beta version. Is it in your signature? If so, the link points to this thread. If not, I'm an idiot and can't find it

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

I can't seem to find the link to the beta version. Is it in your signature? If so, the link points to this thread. If not, I'm an idiot and can't find it

#### isriam

##### Well-known member
Re: Formula for SWG / Pump Runtime?

this is awesome. i hope it gets promoted to pool tool.

#### espejo

Re: Formula for SWG / Pump Runtime?

Second the vote as a pool tool. Thanks MGMoore7. I use the tool and it has been a great and simple check.

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

Second the vote as a pool tool. Thanks MGMoore7. I use the tool and it has been a great and simple check.

#### kcindc

Gold Supporter
TFP Guide
Re: Formula for SWG / Pump Runtime?

Finally got around to using the tool and it seems to make sense for me and my current run time. Thank you!

#### Vickery

Gold Supporter
Silver Supporter
Re: Formula for SWG / Pump Runtime?

I appreciate the work that has gone into this spreadsheet. The soft spot that I detect is that at least the CircuPool and from what i have read, most others, produce at a 100% rate while functioning. The reduction of output depends on the cycle time that the unit is on. There is no variable in the actual output, just the time that it cycles on and off. The CircuPool is based upon a 200 minute cycle, a 50% output means that it is on for 100 minutes out of every 200 minutes that it is on. Reducing the "output" of the unit simply changes the "on" time that the internal timer will cycle. I inquired as to whether the unit is regulated by switching or pulse wave modulation or what method to control the percentage of output. The response was that it is either on or off, 50% means that it is producing chlorine for 100 minutes out of every 200. And that to determine the correct setting requires monitoring and adjusting. The unit works, i can keep my pool sparkling. But the idea that the swcg can be "adjusted for output" without knowing the time sequence and percentage of production will be frustrating.

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

I appreciate the work that has gone into this spreadsheet. The soft spot that I detect is that at least the CircuPool and from what i have read, most others, produce at a 100% rate while functioning. The reduction of output depends on the cycle time that the unit is on. There is no variable in the actual output, just the time that it cycles on and off. The CircuPool is based upon a 200 minute cycle, a 50% output means that it is on for 100 minutes out of every 200 minutes that it is on. Reducing the "output" of the unit simply changes the "on" time that the internal timer will cycle. I inquired as to whether the unit is regulated by switching or pulse wave modulation or what method to control the percentage of output. The response was that it is either on or off, 50% means that it is producing chlorine for 100 minutes out of every 200. And that to determine the correct setting requires monitoring and adjusting. The unit works, i can keep my pool sparkling. But the idea that the swcg can be "adjusted for output" without knowing the time sequence and percentage of production will be frustrating.
It is my understanding that they all work this way but the total cycle might be different. For example, Pentair is based on 1 hour. If I set the Pentair to 100% and the pump/SWG to run for 8.5 hours, then it will only run for 50% of that hour. In your case, you are going to need to run it knowing the cycle of the CircuPool and adjust.

#### mgmoore7

Bronze Supporter
Re: Formula for SWG / Pump Runtime?

UPDATE 8/25/2016: I have completed a number of updates and integrated a suggestion from BestJoeyEver to be able to calculate the SWG % based on the desired pump run time. Here is a quick summary of the updates:
-Changed table to increment by 5% vs 10%
-Added calculation for SWG% based on desired pump run time

#### ndenunz

##### Active member
Re: Formula for SWG / Pump Runtime?

I, too, can not find the link. The first post has been updated several times. Where exactly is it?

Gold Supporter