If you’re in the market for a small, in-sump media reactor, then AquaFX might have something for your consideration. They recently announced their Misty Reactor, which is a small-bodied reactor that can house all sorts of media. Simply unscrew the lid, dump in the media of your choice, and start cleaning that water. Like virtually every other media reactor out there, the Misty uses an upward flow design to maximize the effectiveness of the media.
keeping the reactor upright in the sump is a pair of brackets that attach it to a glass or acrylic wall. A valve is supplied at the bottom (inlet) of the reactor to adjust the water flow, though in the image at the bottom of this post, the reactor is shown to be directly attached to a small pump. Of course, the valve can be placed on the output side of the reactor to keep those flow rates in check.
The AquaFX Misty is priced at $49, though they are currently on sale for $10 less.