I let a lof of algae grow at the top of my overflow. I just keep it from clogging the slits and harvest some clumps of it now and then. It's mostly hair algae and bubble algae...it doesn't seem to grow in the display, but it's always been in the overflow.
You might actually want to consider gluing some "fingers" on there Snow.. - Helps discourage fish from taking a ride over the edge. - Even with a fairly high "gate" I've had explorers find their way in there more than once.
The last time I had one, the little bugger played hide n' seek with me too well and I didn't find him in there for over a month! - When I was nearly done breaking down the tank he decided it was time to come out of hiding. He'd been in the overflow for more than 24 hrs (after I transferred and transported the other livestock) without heat or circulation.
You hear/know of clowns acting kinda goofy sometimes?? - This one was seriously whacked in the head for a few weeks getting used to having something other than black walls and huge white pipes all the time.
Back to the point though.. - Having anything else in there is just that much more to contend with sometime later on when it decides it needs attention. (Usually when you forget all about it and don't have the time to take care of it anyway..)
And really, reaching in to take care of whatever went wrong and then busting out part of your plumbing in the process is probably one heck of pain in the shorts ya know?