Ok - thanks Darrel!Hi all,When you calibrate the probe it should be in the air above the water, not actually in the water. If you don't know what the atmospheric pressure is you can use 1000 mbar and it won't be far wrong. Wikipedia gives you the <"conversion factors">.That is definitely not quite right.
I should note that when it stopped dropping (the DO) it was when the ramp started and then into the end of the photoperiod (it is isn't 3 perfectly consecutive chunks, I had hours where I was distracted and forgot).
Does that make it "closer to right" with those details or there is still something off?
Certainly old. With the info above, if it still doesn't suggest it is right (just off in the calibration as I used the stored calibration), then I will calibrate, and we can see.If it is an old meter there may be a tear in the semi-permeable membrane? If it is a new meter there might still be a seal or cover somewhere that needs removing?
I actually use the fish tanks to make sure the <"membranes are OK">. When the lights are on I pop the probe in the tank, if it doesn't equilibrate to ~100% saturation pretty quickly then I know the membrane is damaged.