Great meter, does PPM, PH, and EC and has a remote probe. Problem I have is the PH gives high readings sometimes. I'll put it in my reservoir, will say PH is 7 or whatever, I'll flip out, take it to the sink and rinse it, maybe drop it in 7 cal. fluid, then a few minutes later its giving correct readings. Usually when it acts up readings are half to a whole point too high. I make a point of rinsing the probe and putting the cap on after use. When I take the cap of its always wet. Whats going on???
I had the same exact thing happen with the same exact unit I determined it was my RO filter that was bad and the water was not ph stable anymore - if you arent using a RO then I dont know but read this and try what I have done if you have the time and see what happens I talked to a friend who said that this can happen but usually its only with crappy RO machines and I had a crappy one regular sink water didnt have this problem here is what I had happen, I noticed the measurement not right from what it was a few minutes ago so I tried some things I took 3 containers of RO water and used a oaktan PH2 meter and normal PH paper and my milwaukee 801 and compared them to make sure they were all saying the same thing I made 1 container 4.0 - 1 7.0 and 1 10.0 then I took 3 more and poured calibration solution into them - 4.01, 7.01 and 10.01 and calibrated all meters I tested the water and it said about 4.0 which it should have said - then I tested the 4.01 calibration and it was again 4.0 - I then tested the 4.0 and it was still 4.0 - then I tested the 7.0 and it said about 7.0 - then the 7.01 calibration and it was agin 7.0 - and the same with the 10.0 one then I tested the 4.0 water and it wasnt 4.0 anymore it was 3.1? - I confirmed this with the oaktan and ph paper it was indeed below 3.5 some how - the 4.01 calibration solution was still 4.0 to the meter so the meter was still accurate then the 7.0 water it wasnt 7.0 anymore it was 9.3? - yep thats what the oaktan and ph paper said and again the meter was tested in calibration solution and it was still accurate again with the 10.0 it was not 10.0 it was 6.5? WTF! the 10.01 calibration solution was still 10. and both meters confirmed this as well as the ph paper something fucked up was going on here and I dont understand it but one thing is for sure and thats that the water was changing its PH when it had nothing in it other then up or down to set the PH level - it was out of the RO which was a cheep lowes brand for under the sink and was probably way past its 2000 gal mark I never knew it was only 2000 gal I though it was 5000 like the other ones I used but when I did the same exact thing with non-RO water strait from the sink I had none of these problems
**interesting** Thanks for the detailed testing. I can't think of why RO water would do this. In my case the problem is with water (tap) with nutrients. But it sounds like all your meters are saying the same thing so its not your Milwaukee 801 meter.