I have it for a short time, but so far it is in the tank, that is fed several times a day by small food (10-40 micron and up) for other corals, this just gets its share.
Other keepers used phytoplankton and Oyster Eggs. Cyclop-eeze for white polyps, or any other food, that fits the mouth - they are relatives of the common yellow polyps.
The lady what keeps it for an year already, uses phytoplankton.
Medium to high flow, they are quite tolerant to the flow. But not too high to break the flattened trunk.
When you will choosing it, take your time: it has to have a base (widening at the bottom), for gluing or epoxying to the rock. And it's better to have a choice: they are frequently very big, around 10" x 10", with multiple branches.
All of this is in the linked page, that I posted before, here is one more link:
thread here at RC, the photos, linked to it, show how the sponge was mounted.
If sponges are living well in your tank, this will give better chances for this sponge too. I treat mine as the any other sponge, and the polyps - as a separate entity, like yellow polyps. That's it.
jacksock at Ultimate Reef, that keeps the red kind, had closed loop pump failure, when he was absent and problem wasn't corrected in time. This sponge suffered the most. Maybe worth to set some backup pump, just in case. My 2 Seios are connected to power backup device.
I found no information, but was suggested, that if sponge dies, polyps may die too. Just passing this to you.