Neptune suggests waiting at least 2 days and I did the calibration almost exactly 48 hours in.Thanks Brett. It's working now. How soon did you calibrate it?
The reason to wait is that you only get one shot at calibration because the calibration fluid is only good for 8 hours after you open it, so before you calibrate it you want to give it some time to make sure that the placement of the Trident and the placement of the input tube are both good.
So keep an eye on it for the next two days or so and make sure that your readings are stable. Obviously there might be a little fluctuation from one reading to the next, but if you’re seeing differences of 2dkh then you know that something might be wrong (perhaps your input tube is near a source of micro bubbles)