You have sponges ; what do you feed them and are they still alive?

[Basile]

I have 2 Ptilocaulis sp. ; a red tree and an orange tree the Axinella bookhouti is a fan sponge that eats bacteria












Put in their right place medium light with strong flow, 2 tunze 6095 on each end and a wavebox at full capacity.






So, what do feed these guys, i red that most phytoplankton is too big for sponges and thats why they starve and die , bacteria where do you get it. I have a few filter feeders food but looking for the best advice and food for them, thanks for your time.