Just purchased the system! Really looking forward to it. I am also a software engineer so this should be fun and looking forward to be part of the community. I actually had this idea and came across this while i was researching.
The first question I had was what you guys were using for your reservoir? Does it matter?
Secondly, are there any modules or is anyone working on calculating/charting VPD and alerting based on VPD? If not I would like to have a crack at adding this feature. There is a system called pulse (https://getpulse.co/) that tracks and alerts based on VPD. I sent them a note on instagram asking how they got leaf temp to calculate and they stated that you enter it in and then you just only need to change it if you move your grow light. But i think I can add an infrared temp sensor to this kit and track it more accurately.
Anyway nice to meet everyone, let me know your thoughts! super excited about my kit
That is a great idea regarding the infrared sensor. Give us some information about how that is working.
For those whom don't know what VPD is, here is the intro from wikipedia.
Vapour-pressure deficit, or VPD, is the difference (deficit) between the amount of moisture in the air and how much moisture the air can hold when it is saturated. Once air becomes saturated, water will condense out to form clouds, dew or films of water over leaves. It is this last instance that makes VPD important for greenhouse regulation. If a film of water forms on a plant leaf, it becomes far more susceptible to rot. On the other hand, as the VPD increases, the plant needs to draw more water from its roots. In the case of cuttings, the plant may dry out and die. For this reason the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 and 0.95 kPa.
In ecology, it is the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. Unlike relative humidity, vapour-pressure deficit has a simple nearly straight-line relationship to the rate of evapotranspiration and other measures of evaporation.