Pinpoint vs Aqua-medic

I having both pinpoint orp n aqua-medic mv computer. My problem is when tested with 230mV liquid, both showing almost the same readings. When dip into the sump tank, the readings are world of difference. Which one is correct?

mV230
Pinpoint - 205
Aqua-medic - 210

Sump
Pinpoint - 350
Aqua-medic - 215

I have also had problems like this with a pinpoint and my cure had to do with cleaning/dipping the probe in a water/vinagar solution for a time to clean off calcium deposits etc.... GOOD LUCK!

Originally Posted by aqua doctor

I have also had problems like this with a pinpoint and my cure had to do with cleaning/dipping the probe in a water/vinagar solution for a time to clean off calcium deposits etc.... GOOD LUCK!

But I thot vinegar will damage the probe

Originally Posted by Bern

But I thot vinegar will damage the probe

No it won't as it is one of the best cleaning agent.

Originally Posted by aqua doctor

I have also had problems like this with a pinpoint and my cure had to do with cleaning/dipping the probe in a water/vinagar solution for a time to clean off calcium deposits etc.... GOOD LUCK!

Hmm I shall try. Thanks. Got myself another AM probe. Same problem!