Sponges are filter feeders they need to be fed a lot. Depending on the sponge the diet will change. Phyto and pods I think are general diets. I think I remember seeing a sponge food available from brightwell or another company like theat.
Sponges are pretty easy to care for, they are filter feeder. Just make sure they are not exposed to air. They do well in a mature reef (>1 year). Many sponges are partly photosynthetic. By having an establish fuge, you can greatly inhence their food intake.