So it's getting pretty good light, it could have been under weaker light when purchased and stretched to increase surface area, possibly, hard to say not knowing all details.
6" should be able to hang unless your clowns are pretty big.
I would probably squirt mysis 2-3 times per week towards it, and maybe once or twice a month maybe give a small piece of scallop, my fish don't seem to chase the scallops that much, and I place right near mouth w/ grabbers, and at times have even held grabbers there if I did have a piggy clown, or cleaner shrimp or something.
You could eggcrate that nem away for a bit if clowns are being too rough, let it grow some, just expect your clowns to get a little grumpy and make sure top has a cover of some kind.