Thanks for all the input!! I still have a few questions.
From what I saw it seemed like you could just leave the PH sensor in the tank for long periods of time with out attention. Is that correct? Also, if I use the wiring diagram (link below) could anybody show me how to get the value from the sensors into an integer so I could use the numbers in my program.
Also, this is not for fish. It's for algae.
Thanks for all of your help!!!!