Hi. My name is Brian and Iím an Excel addict. When I got my SWG I decided to start tracking pump run times, SWG %, chlorine levels, etc. The intent was to just figure out the ideal operating times for my setup. However, I keep adding more and more data points to the equation and have found some interesting tidbits that I thought I would share. (In case anyone else is equally obsessive about this stuff as me.) Some of this could be off base, but I THINK Iím pretty close.
Iím at about 60 CYA right now and still easing my way up to a SWG recommended 70. Iím keeping steady at about 4-5 FC with a pH between 7.5 and 7.7. My SWG produces (by the specs) 20 g of chlorine gas per hour. My pool is in full sun, and 3-5 feet deep so Iíve found about 8 hours a day @ 100% SWG is producing enough chlorine to keep me right even. That equates to about the same as a 2ppm FC loss per day due to sunlight.
Based on my SWG cell amperage draw and my electric costs Iím spending about $0.17 per day in electricity for chlorine generation. The equivalent bleach would be about 55 oz of 8.25% and cost about $1.60 per day.
From those numbers and my estimated season length (June through Oct, thank you heat pump), Iím spending about $21.25 per year on chlorine generation vs an even $200 in bleach. Iím adding ľ of the cost of a replacement cell in my yearly SWG expense, assuming I can get 4 years out of it. (Wildly speculative I know) That makes my total yearly cost for SWG $83.75, vs $200 in bleach. At that savings level it will take me over 6.5 years to make up for the upfront expense of my SWG. (About $760) If we were to factor in the notion that Iím running my pump longer each day to generate enough chlorine, that ROI gets pushed out even further as the pump is drawing the most electricity and pushes my cost up as well. My pump running for 8 hours costs me $1.38 a day.
We could get into other complicating factorsÖgoing to the store and bringing home 60 bottles of bleach throughout the summer vs. the convenience factor, automatic, ďsteady dosingĒ of chlorine, reducing SLAM occasions, etc. So there are lots of what ifs that we could account for and Iím sure spend endless hours and beers debating over. Letís not.
One key lesson Iíve seen if looking at costs is on the pump run time. It all comes down to minimizing that part of the equation. Find your minimum pump run time first, THEN only increase pump run times if not generating enough chlorine at 100% during those hours. If your chlorine is going up on you, donít just back down the SWG%, back down your pump run time. Of course, unless you are already at the minimum.
Anyway, I hope others find this interesting and useful. Iím trying to ďclean upĒ my spreadsheet and then would be able to make it available for others interested in the same. In the meantime, since all threads are worthless without picturesÖ Here is just a shot of my pool enjoying its daily dose of chlorine.