The germicidal bleach is supposed to have extra things in it for E. coli and some other bacterias. You're the first person I know that has used it, though. I have read that it is a great product -just expensive.

The main thing with bleach is to make sure it's plain, unscented, not the splashless kind, and that the percent chlorine is listed in the ingredients. With both bleach and "pool shock", the main thing is to also look at the date code so you know it's fresh. The code will be something like 15169. This means it was bottled on the 169th day of 2015. Chlorine loses strength over time so this is very important. Also, don't buy anything sitting outside in the sun as sun and heat increases the rate of break-down.