Really? I don't know that I'd ever run a tank without one after having one for 14 months. I just finally set up my leak detection module yesterday with a sensor between the DT and display fuge. If it senses water the Apex display will sound an audible alarm, shut the return, skimmer, and heater down, and send SMS messages to both my boyfriend and I. That's just one thing of many it's useful for.
+1
I view controllers as insurance policies for your tank.
The tank crash that made me take a break for two years could have been prevented had I had a controller.
I went to a lake that was 2 hours away from my house for a weekend in july with some friends. Just so happens that weekend my homes AC decided to conk out. My 58 was lit with 2x250watt radiums. I came home sunday to a nasty smell, 95 degree house and lost the tank pictured below.
Now if I would have had a controller with notifications settings, here is what would have happened.
AC goes out, tank starts to get too warm and controller turns on backup fan, temp continues to rise, controller shuts off lights, sends me an email.
I would have sent a friend over with instructions to float ice bags while I made my way back home/ contact HVAC service for emergency repair.
probably wouldn't have lost a thing vs losing a few grand in coral, not to mention years of work.
This is just an example of how having a controller can save your tank from a multitude of disasters.
I run one currently, but I don't use it to run my skimmer or return, mainly temperature/ lighting/ calcium Rx control.
I believe they are invaluable to aquarists that travel or are away from the tank on a regular basis.
Being able to glance at your tanks current, temp, ph/ ORP/ salinity can really
help with the anxiety we all face when we can't be around our systems.