Dunno what an "AquaChem Professional" kit is -- the AquaChem site (http://www.aquachem.com) only lists 'guess-strips' and a 3-way kit, which is really a 2-way OTO / phenol red kit. I'm assuming you have that, with an OTO chlorine test?

If so, you will NOT get a valid phenol red test of pH levels, when your chlorine is at OTO orange levels (ie, > 15 ppm). You'll need to let the chlorine drop before 5 ppm, before you can test pH.