valve /motor automation

Hi, I need some help to understand how to set up (and were to buy) sensors / motorized valves etc to set up automation for an Aquaponics farm. Has any one had some experience in a similar project??

Motorized (rotary) valves are very expensive. What you're looking for is a solenoid valve; the most common type being those that you find on a dish washer or clothes washer.

Searching for "solenoid valve" on eBay, etc., should yield plenty of results. To switch the solenoid on the easiest way is to use a relay board -- and this will work for either AC or DC solenoids.

I have found and purchased some pretty good ASCO solenoid valves from Grainger.com. You can do a Google search for solenoid valves.
Some of the parameters you need to know to make your selection are:
-How many ports. (2way or 3way)
-Max pressure the valve will withstand.
-Max water flow you need.
-Coil voltage you want.
-Type of coil activation voltage AC or DC.
The sensors are depending on what you want to monitor. In order to help you better, we need to know which variables you will be monitoring and their ranges.

You will probably not be able to power the solenoid valves directly from the Arduino. I would use a relay that is powered by the Arduino to control power to the solenoid.

Also, depending upon what the valve is controlling, you may want to specifically choose a default open or default closed valve. If you lose power (and thus control) you want to make sure your valves default to a safe position.

Ex: A default open drain solenoid will open when power is cut and drain your farm dry. A default closed solenoid will close when power is cut and your aquaponics farm will stay wet.

Also, depending upon what the valve is controlling, you may want to specifically choose a default open or default closed valve. If you lose power (and thus control) you want to make sure your valves default to a safe position.

That's right, forgot to mention, Normally Open or Normally Closed as another parameter for the selection.

You will probably not be able to power the solenoid valves directly from the Arduino. I would use a relay that is powered by the Arduino to control power to the solenoid.

If you chose DC as the operating voltage type then you can use transistors to activate them which are less noisy and faster than relays. You can even control the flow using PWM. I suggest for simplicity using 12VDC. That's what I did in this project and I could even control the air flow using PWM modulation from Arduino up to a certain degree. That was just to test that possibility as I don't need that there. Doing that may cause some heat generation though.