New AquaIII arrived PH reading??

[sam08]

AquaIII arrived on Fri 15th hooked everything up, first thing i saw was low PH, 7.8-9 high in the evening and 7.6 over night. checked my Red Sea ph test and was 8.0 to 8.2. waited until tues and took a sample to 2-LFS we sampled my water and thiers side by side same color again with the drops we agreed both samples were 8.1-8.2, i brought the unit with me and it read 8.02 on both samples. since it did reach 8.02 i thought it was probly right. this am it read 7.52, checked again with test kit and read 8.0. I went out and got strips from my pool and spa both read 8.0, would ph strips be off 5pts?
i removed the unit took a large sample of tank water to another room plugged it in and got the same reading 7.52-53
Tank is 180 gal well established 5 year reef, very good coral growth, 4 fish 2-3 years old, 15+ species coral, many inverts, all healthy & thriving
Thanks
Steve

 

[Deleted member 143833]

Did you calibrate the new probe? If not start there; only the temp probe is calibrated, the PH probe should be calibrated before you can fully trust the readings. That said; color test kits for PH tend to read high (so as to not freek people out too much).

A newly calibrated probe is much more accurate than a test kit (IMHO).

 

[sam08]

Yes I calibrated it, also rechecked at LFS, I understand the accuracy of color test but 5 full points? the one i have always used is gray to purple in the 8 range and greens below 8 the test is not green also tried a lower fresh water test and it was the highest on the color scale 7.8 plus, the kits are brand new

 

[Deleted member 143833]

I would still trust the probe, especially if it calibrates. If you have have Kalk you can see if it measure 12 (Kalk is a accepted PH reference).

Note: Kalk is a reference at a specific temp but I don't have the temp handy so it could be a few tenths off.

 

[sam08]

Ok thanks for your help
Steve

 

[dougchambers]

Are you running with temp correction enabled? Most will suggest that you have it disabled...