[Spar]

update: should have checked it again this morning before posting this.

It now reads fine, however once I calibrate it to 7.01 fluid it does not read correctly on 4.01. The controllers don't have both the high/low and 7.0 options like the Pinpoint reader. 4.01 reads at 4.35 or near.

Think I should trust the unit?

 

[CrownMan]

I had a similar problem with my pinpoint ph monitors and found out that I was picking up electrical interference from my light ballasts. I couldn't calibrate it with both 7.0 and 4.0 fluids either but when I plugged the ph monitor into a circuit in another room, it calibrated fine. Don't know if this is what's happening in your case or not. I ended up buying a Milwaukee controller and have not had one problem with it.

 

[Spar]

I had a similar problem with my pinpoint ph monitors and found out that I was picking up electrical interference from my light ballasts. I couldn't calibrate it with both 7.0 and 4.0 fluids either but when I plugged the ph monitor into a circuit in another room, it calibrated fine. Don't know if this is what's happening in your case or not. I ended up buying a Milwaukee controller and have not had one problem with it.

Figured it out. The slope is for the 10/4 fluids, and the Calib is for the 7. Lesson learned on needing to read the instructions first

I used to get interference on my Pinpoint monitor (not the controller) when I bought the AC adapter, but when using batteries no longer got the interference.