Controller, by far the best not to mention cheapest route. Think about what 500 gets you. Ato, light control, timers for dosing, ph and temp control, wave maker, calcium reactor control. Turn off pumps, skimmers during feeding or dosing fuel etc etc. Or make sure your heater isn't on while your chiller is running. See what's using power. Monitor it all on your phone. Your gone all night and wife/partner/gf/bf doesn't know how to turn off pumps to feed. Press a button and done.
Ato - 200 (tunze)
Light control - 75 (ai controller for sols)
Ph monitor - 100 (pinpoint ph monitor)
Tunze wave maker - 250 (for controllable pumps)
Temp control - 50
Dosing timers - 3 @ 6$
Total = 700$
Piece of mind that your cheap timer won't stick or your heater won't stick = PRICELESS
Sure wish I had one on my 90 2 weeks ago. I do on my 30
Even better get an apex to control multiple tanks. Which is what I'm in the works of doing.