The most common item on reef tank to be automated is light. For this, I just use regular appliance timer. Those that are into astronomical timing (moonlight simulation) may use more sophisticated timer, but I am not a big fan of it.

Another item is topoff. This topic is a whole field by itself. I prefer to use electric solenoid-based automation because of the reliability compare to mechanical valves, such as floats.

Lights: Appliance timers

Top off: Can’t beat a litermeter. After years in this hobby, I have read dozens of posts about tank crashes after a float valve failed or how the RO/DI unit kept going, etc. I have read only one bad story with a litermeter failing. Even that one I think it was a lie LOL…………

CaCO3: Oversized kalk reactor. Pays for itself over time.

Huge CaCO3 demands: Large Ca reactor. You thank god someone invented this stuff.

Testing: Probes and probes. pH, temp, salinity

Water changes: Large water container connected via a pump to your sump, so a water change becomes turning 4 valves in 5 minutes.

I have found over time that the best automation tool is actually common sense. If you take 5 seconds to looks at your equipment daily, you will avoid 99% of the problems others have.

I use a SWCD as a surge device for an above tank refugium. The intermittent surge created by the SWCD allows for a more realistic wave-action as the refugium ebbs and flows into the display area. The other end of the SWCD is just piped into the main tank as additional flow.

While I’ve seen some other cool surge setups here I think the SWCD is a very simple and useful device for creating more naturalistic wave/surge action for those DIY-challenged (like myself). It’s sorta automation.

I’ve found my corals/livestock respond better to the intermittent flows (waves) than a constant flow (streams/river), regardless of respective flow rates. I’ve also found that my plankton tend to flow better (thru a drain) with a varying surge rather than a constant trickle/flow. I guess the water’s surface tension affects the buildup of scum/crappie at the drain. This is for the typical gravity-output refugium. It just tends to get clogged over time.