I have a question about some liquid shock I just bought, 4 gallons of 12.5 liquid shock for $2.50. I added 1 gallon to my 8000 gal pool to bring it to about 16 PPM which is just about right for my CYA of 40 - 50. I only semed to raise my CL to about 3 PPM. I figure I've either got something really nasty in my pool or the shock is really old. Does anyone now how I could test the shock to see how much chlorine is really in it? I was thinking about something along the line of diluting it with distilled water to a certain point and then testing that but I don't know how much to dilute it and what it should read. Anyone know how to check this?