hydroponics

I am trying to build an automated hydroponic system using an Arduino board as a controller. I need the program written and the electronics built. 1. The Arduino needs to take a reading of the water tank and adjust the PPM (parts per million) by activating a relay1 that will release the nutrient solution for X ms (still need to determine how many ms are needed to be able to get a change in PPM). 2. A relay2 is activated that turns a small motor on to mix the solution for a time (time to be variable set with lcd screen) 3. Steps (1) and (2) are repeated until the PPM have reached a value: A < PPM < B ---- Once the PPM value has been reached, the Arduino reads the pH: 4. The Arduino needs to take a reading of the water tank and adjust the pH by activating relay3 that will release either an Acidic (if needed) or relay4 that will release a Base solution (if needed) for X ms (still need to determine how many ms are needed to be able to get a change in pH). 5. relay2 (same as above) is activated that controls small motor to mix the solution for a time (time to be variable set with lcd screen) 6. Steps (4) and (5) are repeated until the pH have reached a value: C < pH < D ---- Once the pH is adjusted, the Arduino loops back to the first step Here is the link for boards : [login to view URL] i will supply rest of program once we have discussed price - program is for turning on a pump, lights, vent fan, temp up & down, also co2 on and off sensor for humidity up and down