Pinpoint monitor (PH concern continued)

[toolfan]

I am practically convinced my monitor is junk and I probably should trust my gut and move on...

Last week I calibrated my pinpoint PH monitor and had it dialed in perfectly. dropped the probe in the sump and the reading was 7.2! I recalibrated...got it dialed in and got an even lower reading of 6.7..placed the probe back into the solutions and it came back perfect. Now I am saying to myself..."there is no way I can be running a ph of 6.7! so I test manually with a Salifert test kit and it comes back at 8.0. the kit is a year old..so I go out and buy a brand new one...same result..it comes back 8.0. so I put the probe back into some fresh calibration fluid and it's off..not a HUGE amount mind you. the 7.0 came back 6.8 and the 10 came back 10.7ish. so it appears that over the course of a few days the monitor get way outta whack. what keeps hanging on to this issue is...when I calibrate the probe...place it in the tank..it gives me a 6.7...probe immediately into solution...it checks out accurate..it's not until a few days have past that my probe will not give an accurate reading from the solution. My DKH & Alk are high 13 & 4 respectively.

I think I really just need to throw the monitor in the trash and get a new one. I just have that lingering question in my mind...."Is it really 6.7????" Somebody just tell me to shut up and relax

I perform weekly water changes as I have for years and supplement nothing as it is FOWLR.

[Randy Holmes-Farley]

The pH is for sure not either 6.7 or 7.2. :)

The Pinpoint meter can be prone to electrical interference from certain types of lighting ballasts, etc. That is especially true when using the AC as opposed to the battery.

Try calibrating with the battery away from the tank, and measure tank pH in a cup away from the tank.

Assuming that works, then you can find out how and where it works out best for routine use. :)

[TheH]

1) As Randy mentioned, the old pinpoint AC adapters get interference from heavy-duty lighting systems. American Marine has released new AC adapters that are no longer susceptible to this interference.

2) If you are not using an AC adapter and are using battery, make sure the "LoBat" indicator is not on. Sometimes my monitor will start giving me random readings (usually lower pHs) when "LoBat" is on.

3) Finally, how old is your probe? American Marine recommends replacing them every 18 months.

[toolfan]

I forgot to mention..I switched to the battery a few days ago...no change. The probe is a little older than 2 years. I'll be grabbing a new one this weekend.

Many thanks