Do you think I could mix up a solution of kalkwasser and water and
directly spray it on the small pieces that are trying to take hold to
kill it.

I had some Aptasia and did this and it worked GREAT
Maybe hot water ? Joe's Juice ?

Any thoughts before I attempt ? The piece I want to stop is still very
small but difficult to reach with my hand.Removing the rock is probably
not doable

Thanks