Just heard back from my friend up on the Potomac... the fellow who uses RID-X to get his biofilter up and running for his closed system shedding tanks. I asked him to elaborate on the use of the biofilter and here's what he had to say:
You not only need the rid x, but you must also have a way to introduce bacteria to the system. Fish seem to do the job best, but HARD crabs will also work. The whole idea is to have the biofilter in total working order prior to adding any peelers. The whole process can take about four weeks but is well worth the effort! Mike Osterling of VIMS has a very good book about setting up a closed shedding system.
I assume that what he's saying is that the bacteria need food in order to get established and to thrive. Food, in this case, would be the waste products of live fish or hard crabs. Sounds to me that you need to get the closed system up and running and stabilized for at least 1 month with fish/hard crabs. Once the bacteria colony is fully established and water conditions are acceptible then you remove the live fish/hard crabs and introduce the peelers.