The more OCD you are, the better luck you'll have without a controller. For me, however, a normal human being who makes mistakes - the controller is a game changing device I will no longer live without.
My first 15 years of keeping fish were w/o a controller. I never had long term success w/corals but most of my fish did well and we lived happily. I had a 30, 75, and a 90g tank over those years. I had great success and luck dodging power outages and floods and believed controllers to be an unnecessary expense for either those keeping SPS corals or for the rich with money to burn. THEN in about 3 months, I had a full tank crash and 3 floods. The last one broke my spirit and I tore down my tank. I swore to my wife that it would be back but better and more modern than ever.
Now I successfully grow SPS and have prevented many issues due to the controller. Here are some examples of what it's done for me and why I think it's worth every penny:
1) temp stability. My tank hovers within .4 degrees of my temp target. If it is .5 degrees out of range, I get a text and email alerts. It usually means a window is open on a hot day or someone cranked the heat up too high. If my heater dies, I'll know within plenty of time and be able to throw in my spare.
2) LEAK SENSORS!!! If there's a leak around my tank or in the basement where my water is made, I get a (you guessed it) text and an email alert. This has saved my butt a few times already. I consider these 2 features worth it already. Depending on which sensor goes off, my controller automatically turns off the pumps at that location that could be causing the leak.
3) I can go on vacation!!! Combined with a cheap nanny cam, an automatic feeder, and an ATO, I can make sure my tank is doing well when I'm not home for over a week. The controller allows me to remotely pump water to the ATO container if it gets low. THIS ROCKS and prevent the tank sitter horror stories.
4) If something does happen when I'm not home (at work or vaca), it can allow me to reset, change settings, turn off any of my pumps, lights, ato, etc.
5) If temps are out of range and high, controller shuts down the lights which helps things cool off faster and possibly give me more time to problem solve
6) ph stability and auto control of my calcium reactor. If you want to keep corals and/or dose stuff like alkalinity or calcium, this really helps you do it w/o killing things.
New reefer here. I have a Nuvo 40 Fusion running for about 6 months. I am going to add an ATO, but have been also considering a controller.
Are controllers necessary to keep this tank running for years?
I have a...
Mighty jet return pump
Wavepuck 2
Neo therm heater
Ghost protein skimmer
Thanks