I am in the process of analyzing SWG's and most, if not all the websites indicated that they can generate enough chlorine in a day to keep your 40k pool sanitized. My question is, what chlorine level are they using and how long is the pump require to run to acheive this level? Is their day an 8 hours or 24 hours? If it takes 24 hours to keep the pool properly sanitized you would need to factor in the electric usage into the economics equation (assuming is does not take 24 hours to cycle your water one time). Most of these sites indicated that their system produces an equivalent number of dry lbs. of chlorine per day (2 to 1.45 lbs. per day). I am currently using BBB (10.5% hypo) to keep my pool sanitary and am working in fluid oz. Is there some way I can convert their dry chlorine lbs. into oz. of 10.5% Hypo so as to compare apples to apples? I run my pump enough hours to cycle the water in my pool one time.