[jostafew]

Some people tie the controllers into advanced lighting systems, water movement control (tie in to Vortech, and I'd imagine tunze advanced controllers), data logging when they're monitoring a bunch of params, controlling various dosing pumps, etc. etc. I hope users of more advanced systems will chime in as to what they're doing with them other than looking cool hahah. At their core these controllers are simply logic devices that can accept inputs and make decisions to activate outputs. For example, when the time reaches XX, enable output 1. When input A is on, enable output 2. Things like time, temperature, water parameters, electrical status (voltage, current), float switch positions etc. etc. can be used as inputs to turn on or off various outputs which are usually switched electrical outlets. If you can monitor the condition of something, you can make something else happen based on that condition so really the limit is your imagination. That being said it doesn't sound like your tank is terribly complex so your controller requirements probably aren't either.