Killing coral (on purpose)
 

Just sold a large colony of hydnophora, but it left behind some encrusted base. I won't be able to put anything else in that spot until it's all dead (that stuff is agro!). I can't take the rock out as it's the base of a larger structure, so what's easiest/most effective - epoxy, kalk paste, peroxide, etc.?

Boiling water maybe? Through a turkey baster.

Epoxy or kalk paste might be your best bet if you can't remove the rock from the tank.

I've tried the boiling water and turkey baster on coral before with very limited success

When i did mine i glued a clam shell on top for a month or so

This is the way I do it.

kalk paste will work, I use it all the time to kill off Pocillipora buds. It spontaneously spreads in my tank and I kill the little colonies that pop up before they get out of control.

Rub a ricordia mushroom on it lol. I had one float around my tank for a bit and left little dead pieces of sps everywhere.

On a serious note, epoxy putty and smother it. It'll eventually look like rock again. Or do that and put another frag in its place.

mmkay I'll try both kalk paste and then smothering with epoxy. Thanks guys!

Epoxy didn't work for me when trying to protect my Setosa from my Red Planet. After removing tissue and cleaning the area with a toothbrush I laid down a border of epoxy.

Just over a month later I noticed my Setosa turning white where it was growing closer to the epoxy border. And I saw some Red Planet tissue with polyps on the other side. Somehow it had snuck through under the epoxy, or there was some tissue left there that was not killed when I laid down the epoxy.

I removed the epoxy, and the rock was white underneath where the epoxy was tight. But the rock was not totally smooth, and where there were cracks, the Red Planet survived and grew through to the other side.

So, I guess a lot depends on how smooth your rock is where you apply the epoxy.

On another part of my tank, I have seen a Sunrise Monti do the same thing, and sneak under an epoxy border.

Oh my, that's not encouraging. Maybe I'll just do the kalk paste a few times until I'm sure it's desf

I make my kalk paste just thick enough that its not really a paste, a thick slurry more or less. Just thinned out enough that I can suck it up in an Aiptasia-X applicator, and I use that to pour it on.

Kalk is heavy enough that it holds its form, and falls from the syringe. I used it to kill all my clove polyps … it burns the coral, and then the kalk dissolves over the next few days … by the time it has dissolved, the kalk has burnt away all the tissue on the coral.