Interesting style with the shipwreck, dont see many of those. Super cool looking imo, I personally dont have any however because I like my tank to look natural. It would be pretty awesome to have one, i bet you can put tons of coral frags in the shipI voted every couple weeks because that's when I do it, but it could use it more often. I think it's personal tolerance level, but I do really enjoy looking at it a lot more with the clean glass, so I should probably do it once a week. Pic, for reference, is looking from the side at the front wall. Last cleaning was 2 weeks ago.
As far as what it tells us, I'm not sure. My guess would be nutrient levels like phosphates and nitrates are probably too high. My "typical" algae is the powdery-looking greenish-brown stuff that forms a film (or in spots) on the glass, but over the last month, I've noticed a new, thicker-looking more-brown-than-green kind that seems to look kindof wavy in the water flow, growing in small mats here and there. Any ideas what that could be?