A local pool supply store is selling 1LB bags of 65% cal-hypo granules or 1Gal jugs of 6% chlorinating liquid for $1 each plus tax. Last season I bought 12 of each and used cal-hypo for the first time. According to Poolmath, 1LB of 65% cal-hypo raises FC by 4.3, CH by 3 and salt by 4.4 in my 18,000 gallon pool. One gallon of 6% chlorinating liquid raises FC by 3.4 and salt by 5.6 and adds no CH. Our fill water adds very little CH and our level is often 30PPM or so.
Since CH does not really matter in a vinyl lined pool, as long as I stay within the TFP recommended range of 0-300PPM, I see using cal-hypo over chlorinating liquid a better option. I'm not saying to use it as my primary method of chlorinating but rather as a supplement to my SWG when I have a heavy bather load or to perform a SLAM (if needed). Also, the cal-hypo is stabilized and wont degrade as quickly as the liquid. It is also more environmentally friendly with a lot less plastic than the gallon bottles.
Is my logic sound?