I wouldn't do it only because its going to breakdown first into high levels of ammonia. Unless you have killer bioload capacity that can cycle to NH3/NH4 to NO2/NO3 quickly, it could create problems for delicate tank inhabitants and is very likely to spark cyanobacteria or dinoflagellate blooms.
Processed food.. detritus.. from established tanks would be so much better for this application and getting organic matter into the substrate.
>Sarah