I am the happy owner of a mancave and I've decided to invest in raspberries, sensors and some small hydroponics vaxer from ikea. I've gotten a camera and some temperature sensors which can log pictures and temperatures/humidity to the cloud.
A next step would be to measure the nutrients in my hydrophonic system as well. I'm having trouble finding proper sensors for it though. I'm interested in hearing of any sensors that might be applicable for a hobby project or what the possibilities might be. Any experience or references are also welcome.