Agree with the plywood. Then polyurthan it. I would go with a refugium. Not really hard to make. Just through sand (DSB or not), rubble, and cheato or mangroves in it. Sand and rubble are opitional but having cheato mangroves or something that will suck nitrates is the point of a refugium. As gives a 'refuge' ,go figure that one, for pods and such that would be eaten by variours fish.