So I have this purple sponge that grows on random corals. It first took over a colony of candy canes, then a colony of Hawkins, and now it's taking over a colony of cats eye. I've tried exposing it to air and pouring hydrogen peroxide on it but all it does is tick it off for a few days then it's back to normal. I've stoped dosing sponge power to slow it down and I moved it up closer to the light to see if that will work. How can I get rid of it without harming the cats eye?