I took a peek into the overflow box and there is a fair amount of algae and gunk in there. Should I clean it out? The tank has been running for 1 year 4 months and I haven't cleaned it yet... any feedback is appreciated.
Yep I would just clean where the water flows. So up around the top and around the pipes a bit. But honestly no need to clean it all out unless you need to get at the bulkheads or something. Your overflow is basically a cryptic zone and life will grow in there. Most of that life is a good filter for the water, so just keep the water flowing smoothly through and you should be good to go.
Yeah, mine has all kinds of life, tube worms, algae, etc. I just make sure that the siphon U tube is free of stuff. I hist buy cheap tooth brushes and clean it now and again.
I cleaned mine once and found a clown fish back there! I thought he had died in the tank somewhere since I never found his remains. Turns out he had been living in my overflow for over a year! When I tried to reunite him with his fellow clown that I bought at the same time he was rejected and picked on until I pulled him out and sold him.....along with a great story!