Quote Originally Posted by cheshamjim
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I have no way of knowing how far above 5 ppm it might be, since my test kits (DPD #1 and OTO) only read to 5 ppm. I'm wondering if I could dilute my water sample with a measured amount of tap water to get a reading that shows on the color comparator, them multiply by the dilution amount.
You can diliute and in fact it is a standard procedure with both OTO and DPD testing (DPD bleaches out at high levels of chlorine) but I would not go over a 4:1 dilution. With each dilution you lose accuracy. Easiest way is to use a shot glass or some similar measure and dilute with distilled water.....
for a 1(pool water):1(distilled water) dilutiion multiply reading by 2
for a 1(pool water):2(distilled water_ dilution multiply reading by 3
for a 1:3 multiply by 4
for a 1:4 multiply by 5

for how high you need to go with your chlorine it is somewhat dependant on your cya levels ....see this post for details on how high to bring your chlorine up to shock effectively and get rid of the CC.
http://www.poolforum.com/pf2/showthread.php?t=365