I used to when I ran a big one that was a separate tank. I'd try to siphon the bottom of it, as I kept it bare bottom. I would do this about once a month. And a few times a year, I'd prune the chaetomorpha and give the whole thing a solid cleaning. After seeing all of the silt and build up in the bottom, I'm sure a lack of cleaning it would have lead to waste products remaining in the system and possibly leaching back out into the water column.