I had a terrible outbreak of cyano in my 29G at one point - and I just vacuumed as much of it up as I could and did my normal water changes and backed off of the feeding a bit and it pretty much cleared up on it's own. The only time I really had issues with it after that point was if I went more than a month or two without at least a little bit of a water change - but this was a 29G with a HOB filter, HOB skimmer. It was ... pretty low-tech I guess you could say.