You'll find that almost none of us on this forum will use test strips for anything but ballparks, because they are considered to be very unreliable. As for your CYA level, I would not trust any level that is obtained by any other way than with chemical reagent testing. If you do indeed have a CYA of 100, then you're going to have a hard time keeping algae out of the pool unless you run a chlorine level of around 10 (minimum) all summer. I do run my CYA at 80 - 90, but I am very consistent with keeping my chlorine levels up. I live in Louisiana and my pool is in full sun all day, so that's the only way I can keep chlorine in the pool. My suggestion is that you drain and refill, at least small amounts, as often as possible to bring the CYA down a bit. I wouldn't even leave mine at 100.

Janet