PLC Fish Tank Controller Project

[cinci]

i started working on lighting program to simulate the lenght of day light at the great barrier reef. never did finish it. there is alot you can do
i picked up a bunch of float switches and planned to use them in series in case one failed. two for high and two for low.
both would shut the pumps down or sound an alarm. my master plan was to have an automated water change. just push a button.
i haven't really found a cost effective way of doing ph or orp. i wanted to graph as well. i see some of the newer controlers now offer some of these features. i just like the fact that you can program the inputs and outputs yourself you can add alot of safety. i always get as kick out of people who post stories about how there auto topoff float switch stuck and nuked their tank, with a plc you could program the lenght of time the pump runs before the float switch should make if it didn't shut if off set an alarm.