I'm currently experimenting with riparium's for filtration. I have a plastic window planter with a hole cut in the side for the output of my canister filter and I just stuck it on top of my tank. It's wider than the width of my tank, and so it's only halfway in. It also helps buffer the flow, because it has like 10 tiny holes placed all over the bottom so the water flows evenly through the holes.
I crammed it full of pothos, and peace lilly. so far it's not working quite as well as I had hoped, but I think it's taking a while for the plants to acclimate to semi-aquatic conditions. I have a uncycled 30 gallon rubbermaid bin as a temporary tank and my daily ammonia levels are lower than i expected, but still not 0. I did cram some pothos and peace lily in a hob filter of my uncycled shrimp tank, and I have 0 toxins at all in that tank, so I think theres hope. I know shrimp have a low bioload, but it's like over 60 shrimp in a ten gallon tank, and I havn't changed the water in weeks.