Agree with Strike on #2 comment also :
2004 Post:
OK, here is my sure fire way, 100% success rate, never to return again method.
Use a saturated solution of Sodium Hydroxide (Drain Away, Draino, whatever you like to call it) and water. Using a syringe, squirt about 0.5 mL into the mouth of each aiptasia. This will kill even the stubborn foot tissue.
I initially used kalk paste like pies, by found that the success rate wasn't that great. Sodium Hydroxide is much more soluble than Calcium Hydroxide, and is more alkaline, completely nuking the aiptasia.
Again don't dose too much at one time. It is not harmful to your reef, unless you directly squirt it onto corals. Just a warning that Sodium Hydroxide will cause sever chemical burns if handled, you can tell if you have it on your hands 'cause they will feel "soapy" and slippery. If you feel your hands becoming slippery, wash with a LOT of cold water. Preferably wear gloves when handling.
As dangerous as the chemical sounds, it is really quite safe for your reef.
Draino is surprisingly pure sodium hydroxide, and is really no more dangerous to your tank than calcium hydroxide (kalk). Any tank with a reasonable alkalinity (greater than 2.6) should have no problems adding it. The hydroxide ion reacts relativly quickly with dissolved carbon dioxide producing, there are also other mechanisms for the neutralisation of the free hydroxide. Which reaction is most significant is determined by the pH.
2(OH)- + 2CO2 ---> H20 + 2(CO3)2-
The only difference between this and the kalk method is the spectator ion (Ca2+ as opposed to Na+).
Kalk will do the same thing to your hand as sodium hydroxide, at a much much slower rate.
If anything this method is easier on the fish, I had problems with fish eating, or trying to eat the white kalk paste. I for one wouldn't like a mouth full of kalk. The sodium hydroxide method is much safer in that it is completely soluble, such that any solution which doesn't make it into the aiptasia, is quikly netralised by surrounding water by the above reaction, and no solid remains to be eaten by fish.
