PH levels

[Squiers007]

I work in a water quality lab and when we calibrate our pH probes (which we do everyday I might add...) we only use 3 calibration points 4,7, and 10. Since we are only reading pH levels between 7 and 8.5ish for our tanks, using only 2 calibration points is fine. As others have said, make sure to leave the probe in the calibration fluid until the value stabilizes. One way to make this go a bit faster is to swirl the probe in the fluid so it is evenly mixed. We use stir bars and have the liquid constantly stirring while calibrating and taking readings. I'm not sure what kind of drift the probes have but if possible I would recalibrate every month (the more often the better).

[zerreissen]

Thanks guys, I calibrated the probe right before I put it in the sump a couple of weeks ago. I just bought 12 #7 and #10 packets so that I can calibrate on the first weekend of every month. I re calibrated by putting the probe directly into the packet and had the packet held with an algae clip in the water in the sump (for temp sake) and left it there for 25 mins. PH now reads 8.09, which is much better.