I can't do that math for you either, but if you'll go to WalMart and see if they have the hth 6-way drop kit, it has all the basic tests, including CYA, that you'll need until you can order the bigger kit. Your best bet would be to just run a set of numbers and go from there.

If the pH of your fill water is less than 8.0, then draining/refilling with lower pH fill water will probably have dropped your pH. IF your fill water is high in pH, then it's probably going to take some acid to lower it.

Kudos to you on using methods that you know are working for you--and having more $$ to spend where you need it, rather than at the pool store.

Keep in mind that the higher CYA is not necessarily a bad thing--it can drastically slow your chlorine loss, and allow you to dose the pool less times per week.....you just have to maintain a higher baseline chlorine to compensate. At first that might seem like it uses more chlorine, but it requires no more chlorine to shock a pool from 5 ppm to 15 ppm, than it does to shock it from 10 ppm to 20 ppm..... I run my pool at 80-90 ppm CYA on purpose, and I'm comfortable with running it even higher than that...it's just that my chlorine loss is less at 90 ppm than at any other value I've tried. (See the 'best guess chlorine chart" link in my sig for more information on that)