Nice meeting you today. As we discussed, the Apex forums are full of the same question about the probes and calibration. Since it’s new, give it 2 or 3 weeks in the water and then re-calibrate it. I gave up on the calibration fluid and used a refractometer to get my tank exactly 026 and the I calibrated the probe with my tank water. I’ve had it going this way for a year and it’s only about .5 off. But I know it so I just keep my water at 35.5 now. Lol