Button polyp control

Hello,

I have two pieces of live rock that have star and button polyps. The
rock has been in my tank for about half a year and those polyps are
spreading like weeds.

I intend the tank to be SPS/LPS and I've heard that star polyps tent
to overgrow SPS corals. In addition I don't have activated carbon inmy
tank, so I preffer to have limited number of softcorals (i.e. one
yellow leather coral taht is also growing very fast)
One of the rocks is on the wery bottom of my takn and removing it will
be VERY problematic and potentially disasterous. Another one has a
sponge groviing on it which I'd also like to keep alive.

Is there a way to keep them at bay (short of just
killing/shreading/ijecting with kalkwasser)?

Thank you
Yuriy