I have been using TFP for a couple of years now and have not had a green pool for a long time .
All I do is use a Taylor 100 kit and test for chlorine and PH every morning and add bleach acid as needed. Very occasionally I do a full test but all it tells me is what I already know!
However something funny happened the other day.
I looked at the PH and it was high around 8-8.2+. So I shook the tester violently and the PH went to 7.2.
I tried this a few times over the next few days and the same happened. But not today it showed 7.6 and stayed there after vigorous shaking so I am completely flummoxed!
I am sure all is ok just wondered if anyone else had had this happen and whether a vigorous shake rather than a couple of flicks of the wrist is really needed?