I could use some help in selecting hardware for a water level sensor. I was hoping something would already excists so that I could jump into integrating the solution quickly but so far I haven't found what I'm looking for. Perhaps I'm thinking/looking in the wrong direction so let me first explain my modern world problem
I'm not very kind to my plants. I generally don't water them in time. First I put it on my work and the traveling that comes with it but this pandamic year brutely exposed my own pure shortfall. I just forget! Last year I started to replace my traditional plant pots with ones that have a water reservoir. Depending on the plant and size of the pot you only water them once every few weeks. Great for the holidays to come! But it turns out that I forget to water them even more!
Below is a picture of how these pots work. There is a water reservoir under the plant with 4 or 7 cm of water. There is even a water level indicator which I consistently seem to ignore!
What I would like is a small, battery (ie CR2032) powered, sensor that can report wireless to Home Assistant when the water level is zero. Through MQTT, for example, but anything else will do too. Getting the state once a day should be enough. Nicer would be to have multiple states (100%, 75%, 50%, 25%, 0%) and perhaps increase the update frequency to 2x a day. But this is all extra.
I looked at several sensors and projects but they come with different kind of ceavats. They use a big board that consumes too much power for a small battery like the CR2032. My best bet would probable be to have 1 or more read relays? Perhaps then I could only initiate an update when the level has changed? Or I could try to read somehow the level of the existing level indicator. This basically is a cork on the water, pushing a red plastic pin up or down.
Any thoughs are welcome.
ps I thought about getting a common available moist sensor which would work for the inside plants but I'm using the same pots for outside and then rain could generate false readings.