Robo-Tank v5.0 Screenshots and Flowchart - Ideas Needed

[Rob F]

If you didn't use a temp sensor then you would want the solution to exactly 77 for a perfect 4.01 or 7.00. Temperature does change PH, pure water is 7.00 at 25c or 77f but there is a common formula used to adjust the offset from the temp. If your 4.01 was 68 it might actually be 3.99 or 4.03, not sure which way it swings off hand. But once your water temp of 68 is added to the formula the ph will come out 4.01 like it should. A lot of cheap PH meters just use the default 77F but more expensive will have a temp sensor built in so the 77F can be replaced with the actual temp, that's what the controller does. When I added temp calibration to the controller I didn't think it was working properly because I couldn't see a difference like I expected but then discovered it has little effect so even if it wasn't temp calibrated I wouldn't be too worried. Maybe for other parameters it's more important but I can't imagine someone caring too much if ph was truly 7.15 but came out as 7.12.

But yeah you can leave your solution at room temp and put the temp probe in to get the most accurate results. Remember to clean the probe really good as it doesn't take much to contaminate the solution especially if you reuse it.

On the controller side currently the water temp sensor is used to update the circuit with the temp, I think its being sent every 10 minutes or so. When you calibrate you have to use temp sensor 4 on the controller instead of the the water temp port. During calibrating the temp is sent to circuit after every couple readings. In v5 you'll be able to select any temp sensor.