[SubRosa]

Here's an idea I have been tossing around for a while,although the 12" depth of a 55 will limit things somewhat.Basically you glue dividers into the tank to partition off a dry land area.These dividers are drilled for drainage.Build up your land area with gravel,leaving room for a 4" layer of topsoil,and any structural features you want.You want the bottom of the soil layer an inch above water level.By pumping water up onto a waterfall and allowing it to trickle through the soil you get serious biological filtration.I have a 180 sitting that is going to get this treatment soon,complete with external plumbing and a sump set up to maintain a constant level in the tank.The extra depth of 24" will really come in handy!