PinPoint Calibration Solution off?

[-=DieselDave=-]

I bought ten of the 7.0 and ten of the 10.0, I have just started using them and they seem to be off from the other fluids that I have used by about -0.3, Lot 2510170 on the 7.0 and lot 2508003 on the 10.0. I'm not sure if they are off or the old solutions are off or my ph in both of my tanks (one with a sump outside) are both reading are 7.9 - 8.0(low) this is after calibrating two different meters with these solutions. Test kits (salifert) they seem to be reading 8.2-8.3(they are a bit hard to detect the color for me).

Could someone please look into this for me?
Thank you,
David

 

[hounddog01]

What it the tempeture of the fluid. It can change.

 

[-=DieselDave=-]

I would say they are very close to 70 degrees Fahrenheit they are stored on a shelf next to my tank. I keep my house at 70.

 

[zman90]

Dave,

That is funny you say that. I felt the last two times I calibrated, two weeks apart because I thought I misadjusted. Lower than expected results the first one did a second time with the same new lot. Ditto on the Salifert pH paint chip card. My lot numbers are different though. 10.0 - Lot 2508004, the 7.0 is completely different Lot 2506054. I wonder if the 10.00 are the ones off and how many Lots could be affected.