You can operate a pool at high CYA levels but you'll need to know how high.

Dilute the pool water with an equal measure of tap water and test the mix - if it's 100 or less, multiply by 2 for your CYA. If it's still over 100, Mix one part pool water with two parts tap water and measure the mix and multiply by 3.

pH readings may be a problem, I've read somewhere that if you let the phenol red test sit for a while it gets closer to the correct color. Theres also the option of electronic pH tester but if you go that route, you'll need to handle it gently and calibrate it regularly with a standard solution.