Quote Originally Posted by PoolDoc

One caution: phenol red is NOT stable with chlorine levels above 3 ppm. The phenol red from Taylor, used in the PS200 should be stabilized to 10 - 15 ppm chlorine, but above that will give various false readings.

Ben
Do I read this correctly? you said 3 ppm. I don't have that much because I run very low CYA (20) and the pool is mostly in shade, but most people here run over 5 ppm in chlorine. How then can they test the PH?
I will test the buffer tonight. I bought my PS kit last year (August) and have last years test soloution and also reordered refill for chlorine and PH last month. I will give it another try and will also compare with the pool company. Thanks all.
Amir