Achieving perfect zoa colonies??

I see pictures all the time of perfect little zoa frags that only contain that specific species. Two of my zoa frags have 2-3 brown button polyps and I was wondering how to remove these? I tried using a syringe with boiling water but after a week or so they just came back(after looking pretty dead imo)

I don't like the idea of adding any chemicals also they are so close to my desirable polyps it's tough work just isolating the brown's.

Any advice from some of you expert zoa colonists?

Here are some photo examples for all you visual junkies! B-)

Example of mine:


Example of what I'm hoping to achieve:

 

kalk paste in a syringe directly in the mouth of the zoa. ive done it several times on colonys. as long as your get it right into the mouth of the zoa you dont want it should be all good.

 

ty, +1 ... i've heard a lot of people using this kalkwasser stuff... so it's not just a really good calc dosing agent but can also be used as a paste to get rid of undesirables? interesting, i wonder if my "purple up" or just direct Calcium dose to the face won't have the same effect?

 

Aiptasia X kills them sometimes also, but if any of the body tissue lives they will come back eventually...even if just from a few cells.

Laboratory isolation techniques would work best to eliminate the brown all together... basically you divide your sample into a larger number, so you have between 3 and 6 polyps per frag, and/or get at least 4 or 5 frags with no obvious brown polyps growing. Look for the tissue, even if there's no polyps, it can cover a lot of area.

Grow out those frags, and watch for brown polyp growth. When you've got 20-25 new polyps on each frag, look for ones with no brown, and frag those... if any have brown polyps on them, frag those the same as round one, and keep going from there.... after at least 2 generations of no polyps in your frags you can be pretty sure it's gone....



Of course, I also find that healthy zoa colonies usually crowd out competition and form borders with neighboring colonies that slowly shift and sometimes intermingle. I have a few interruptions in my mats, but once they get large it's not much of a distraction, so maybe just let them grow... and see what happens.

here's a bad pic of one of my larger colonies... I would guess there's at least 1000 polyps in my tank right now of about 10 varieties, and maybe 2 or 3 points where anything has managed to grow among them.

 

Maybe take them out by using cutters and a drill *evil grin*