With the glue-putty-glue method, A little goes a long way. If it is 5" in diameter you may only need to use 1/4 of the putty and a loonie sized dab of glue on each side of the putty will suffice. You only need enough to make a solid contact with the coral and the rock. Make sure you twist it back and forth to fill the nooks and crannies of the rock.

Thanks reefie, that means I will spend less money than what I thought :mrgreen:
I will try to do it again. The last time I was spending almost the whole tube of the epoxy and it still didn't harden fast enough for me to have enough patience to hold it on, even with all the powerheads turned off for 5 minutes. The epoxy was falling apart after like flour and caused a terrible cloudiness in the tank for that whole night. I couldn't make it as a Mexican stand-off as cuz said.

Like I said earlier, less is more. The more putty & glue you use, the longer it will take it set.

This is how I would do it:
First: Cut about 1" of epoxy putty and knead it until well mixed
Second: Shape the putty into a circular shape
Third: Add a little bit of Super Glue (Try to find the thicker stuff, it works better. I'm using the EcoTech CG bottle) onto the middle of the putty "disc" set it aside
Fourth: Grab your colony and take out of the water, pat dry the underside (The water prolongs the curing process), and stick the putty disc onto the underside of your coral, leaving it a bit thicker.
Fifth: Add a few drops of Super Glue to the bottom of the putty disc in various spots, keep in mind that the putty will be smushed and will stretch out.
Sixth: Move the coral where you want to place it, twist it back and forth, and hold it there for a minute or so, make sure the coral is in a balanced position as it may be top-heavy
Seventh: Dry your arms and enjoy. ��

This is what I use:
http://www.jlaquatics.com/product/mc...k+-+4+oz..html
http://www.jlaquatics.com/product/mc...2875ml%29.html

Thank you and thank you reefie :mrgreen: I will follow your instruction.

Alternatively you could pull the rock out of your tank and drill a hole in it. Then glue a short length of acrylic rod to the bottom of the colony. Then slip the rod into the hole. This is a great way for securing smaller frags but it also works on large pieces.

That is another cheap alternative for me, but unfortunately I am unable to move the big flat rock to drill it without breaking other corals. It is encrusted with lots of different corals on it. But I will use your method for other small corals on the removable rocks in the future. I would have saved quite a bit of money I spent on glue if I would have known this.
Thanks for your input.

What about draining some water out of your tank, enough so that the spot on the rock that you would like to mount to is exposed. Then drill it where it sits and refill the tank?

hehe ... will scare the hell out all my fish. I don't want they hate me whenever I come close to the tank though. It took me so long to let them feel comfortable and happy to see me. I can move my arm around the tank and none of them run away, they actually want me to pet them sometimes. I know you love your fish just like me, so you know what I mean :razz: But I have to say, you really have a lot of brilliant ideas though. I can tell you can do a lot of things around your tank.
I have a lot of small colonies, I am going to do with them the way you told me, but outside the tank only.