NO. I would suspect the indicator solution is not reading for some reason. I would clean the drop checker and put in new Ph indicator solution then check. OS.
I have the GLA Pearl also and really like it. I always carefully remove it and position on the outside end of the tank until I'm done with my WC. My solution is still reading OK after 4 months. But I'm going to replace it next week just to be safe. OS.
PJFISH,
Did you change out your indicator solution yet? Did it solve your yellow color problem?
OS.