Ok, I have some pretty big sponges it would be welcome to eat. I also don't mind buying sponges regularily if needed. Although I would prefer for it to eat prepared foods.

somehow my sponge never seems that is going smaller eventho my angels nips at it all the time

I have two Emperors in my tank for over six months now, a 6" and a 4". The smaller one doesn't touch any corals. The larger was a good citizen for a couple months and then it started eating some of the zoanthids, nothing else. IMO, large angels are safe with sps, not soft or LPS. Dwarf angels are safe with soft and LPS but not sps. Of course keeping the angels well fed will better your chances, however, in a confine aquarium, these animals will eventually get bore and try things that would never occur in a wide open reef. I keep a mixed reef and losing a few corals every now and then is not an issue for me.