I wouldn't use any more cal-hypo. Your CH is getting too high. Just use bleach. (Plain, unscented generic Walmart 8.25% bleach is fine.)

If one scoop of the DPD powder turns the sample pink, no need to use a second scoop. Also, to make your testing reagents last longer, just use a 10mL sample of water and multiply the drop count by 0.5 instead of 0.2. Especially since you are going to have to run such high chlorine levels, you're going to go through the reagents fast. You can also use a 5mL sample, and multiply the drop count by 1. That would make them last even longer.