A moisture sensor is little more than a couple of parallel wires; when wet they will conduct electricity between them. You just need to add a resistor to tone down the current that's constantly running through the wire.
Using the moisture sensor in a way that would allow it to get repeatedly wet would (assumedly) result in it getting scummy and failing to read correctly. I don't think it's a good long-term solution.With respect to what Arduino you need your primary requirement is that you have enough IO pins for your project as it certainly isn't a processor-intensive task. There's 14 digital and 8 analog on a typical board. A Mega will give you more of both or you can add on an IO board like the Mux Shield. Whether or not you use multiple boards really depends on whatever you think is practical -- taking into account that you might need to create communication between them which could create headaches in itself depending on the distance you need to cover.
An Archimedes-Screw on a servo motor set to spin for 1 second and then shut off for 4 hours.
electronic PH tester to check for PH drift and changes once per hour and report to a Linux PC.
the room lights to allow for the grower to see should be activated, simple t5 tubes (aprox. amount of tubes: 2-4)
Hehe. I think we need a project to have an Arduino alert us of the cops being suspicious of someone Automating Lights/Feeder/Pump for Aquaponics using Arduino.Then we can make the project of Automating Lights/Feeder/Pump for Aquaponics using Arduino.Unless of course they let you develop Arduino projects in jail. Hmm.....