If you're lucky enuf to get it to thrive in your tank, sooner or later it'll almost feel like a curse. It's beautiful stuff. Gives you that warm and fuzzy about your tank seeing all the flowing back and forth while pulsing as it does. Then one day, you MUST start cutting it back. Feels good. "Wow, it's healthy!!".
Then, it starts taking up too much real estate. The curse.
Pom pom does grow slower than the elongata version. Plus its prettier. But it can spread and get thick too. Pruning will create the mucos mentioned. So will the densness of it even if not pruned. It can crash suddenly and kill off inverts in your system and other coral. No reason why.
Anyway, if you must try it. It can be fun. Gotta be vigilant. Good luck.