SWG Generation Capacity

[sbcpool]

Is there somewhere I can get or calculate the total chlorine generation capacity of various SWGs? I have a single speed pump and I want to calculate how long I'd have to run my pump to generate approximately 250g of chlorine per day (+3ppm in 20,000 gallon pool). This is a factor in my decision to go the SWG route or the dosing pump route.

If this chart is accurate, the Pentair IC-60 would require about 6 hours of run time, and the CircuPool RJ60+ would require about 4h 15m.

 

[mknauss]

That chart is accurate.

Or you can use the Effects of Adding Chemicals section in the Poolmath app.

 

[sbcpool]

Thanks for the top on Poolmath. I don't install apps because there's no way to verify exactly what they're doing, but I did dig up the old Poolmath page.

 

[mguzzy]

I'm guessing that is the output when the controls are turned to 100%. You will find the dynamics of your Chlorine to be a little different on a SWG compared to liquid chlorine. There is a sanitizing effect of the water going through the cell itself. I have a Hayward TCell15 and have no problem keeping my 20K pool at about 3ppm. It runs about 5hrs a day, with knob set to 50%. most of the time

 

[ajw22]

I'm guessing that is the output when the controls are turned to 100%. You will find the dynamics of your Chlorine to be a little different on a SWG compared to liquid chlorine. There is a sanitizing effect of the water going through the cell itself. I have a Hayward TCell15 and have no problem keeping my 20K pool at about 3ppm. It runs about 5hrs a day, with knob set to 50%. most of the time

Pool FC levels depend on CYA level. See FC/CYA Levels

SWG pools can be kept at a lower FC level than LC chlorinated pools due to the continuous CL generation of the cell. You dont have a FC loss during the day. That effect only works when you run your pump and SWG for the majority of the daylight hours.

 

[mguzzy]

I was speaking of the effect that happens in the cell chamber, where there is a high level of chlorine during generation and all the water gets pumped through it. I have seen this discussed in other threads. This cannot be reproduced with a dispenser.

 

[sbcpool]

Thanks guys. My concern was having a single speed pump. Because of electricity prices and TOU rates I only run for about 3 hours at night, or during a pool party. If I go the SWG route I want that to be enough run time since electricity is expensive. Each additional hour of run time adds about $100 per year.

Having to run the pump even one additional hour changes the ROI model completely, adding at least $500 additional expense to the SWG's cost over the cell's lifetime.

 

[ajw22]

Get a VS pump with the SWG and your pump electrical costs will drop by 80-90%.

 

[sbcpool]

You're telling me a VS pump operates at less than 150 Watts? If not, it's not going to save 80-90%.

EDIT - Even if it does save 90%, you have to prorate the cost of the VS pump into the savings. It takes about six years to recover the cost of the pump from the electricity savings. Not worth the investment while the single-speed is still working, but definitely when it's time to replace it.

 

[ajw22]

From Best speed and run time for a variable speed pump

we have the Hayward TriStar VS pump, I believe it's 1.85 hp. Based on actual KW from 15 minute intervals on a smart meter, here's the results:

100% output, 1.59 KW, 3450 RPM, 0% KW reduction
90% output, 1.17 KW, 3100 RPM, 26% KW reduction
80% output, .83 KW, 2750 RPM, 48% KW reduction
70% output, .58 KW, 2425 RPM, 74% KW reduction
60% output - never chose this one
50% output - .24 KW, 1725 RPM, 85% KW reduction
40% output - .14 KW, 1375 RPM, 91% KW reduction

 

[mknauss]

In California, you can only now buy variable speed/multi speed motors (above 1.1 THP)

 

[sbcpool]

It's up to a 90% reduction for the same run time, but you have to extend the run time to get the same level of filtration. If I have to run for three hours at 100%, I have to run 7.5 hours at 40%. That works out to an 80% reduction. At my current electricity prices it will take almost 11 years to recover the cost of the pump.

 

[mguzzy]

It's up to a 90% reduction for the same run time, but you have to extend the run time to get the same level of filtration. If I have to run for three hours at 100%, I have to run 7.5 hours at 40%. That works out to an 80% reduction. At my current electricity prices it will take almost 11 years to recover the cost of the pump.

So it sounds like the best time to put in a SWG would be when its time to replace your pump. I can put a dollar amount on the time I've saved with an SWG and it paid for itself in a year. If I was retired and time was not money.. I would look at it differently from the pure cost perspective as you are doing now.