Richard Evans

OK newbie here with a problem. I have ran a hot tub for a few years. Last week I brought a new one along with a Apera PH20 digital PH meter which is well regarded. After calibrating the unit with PH 7 and PH 4 solutions with no problems I believe it is working fine. However, when i use it I get a PH of 8.1. I have 3 brands of test strips which show 6.8, 7.2, 7.4!!!! So the test trips say OK or low while the calibrated meter shows it is high. Which do I believe?????