How to kill aiptasia with pickling lime or kalkwasser mix
1.) Mix 1tablespoon and 1/2 teaspoon of Mrs. wages pickling lime with 1 1/2 Teaspoons of water to make a nice paste. The paste should not be running, but it also must be thin enough to get injected through the syringe.
2.) turn your powerheads off, Apply a layer of the paste to the oral disc of the aiptasia. Sometimes you can get them to think its food by teasing their tentacles a little and then injecting the paste onto the oral disc. If they suck back into their hole right away just cover the hole with the paste.
3.) wait 45 minutes to an hour
4.) suck out the paste and the aiptasia with a turkey baster and dispose of them.
If you don't get the aiptasia out with the baster, try again. make sure you also suck up any left over paste. And don't get the paste on anything you don't want to kill.
I bought 100 lbs. worth of live rock from a fellow reefer who was tearing down her tank. The rock was covered with aiptasia (estimating over 300). Some of the rocks also had some corals on them (mushrooms, green star polyps and Kenya trees)
I put the rock on a 55 gallon tank that I used as a holding area while I treated the rock before putting it into my display tank.
I mixed up a small batch of the lime paste and started injecting the aiptasia with the method used above.
I recommend doing only a few at a time as the paste can cause a PH spike in your tank if you do too much. Keep in mind Pickling lime and kalkwasser are similar products that are used for correcting alkalinity and calcium problems and can be used safely if in small doses.
Be sure to cover the whole face of the aiptasia with the paste to ensure that it cannot release its seed into the tank and make more aiptasia later. You also must get it out of the hole as even a small piece of aiptasia can grow into a whole one over time. Do it right the first time.
Other methods that work include Peppermint shrimp, Copper banded butterfly, joe's juice, aiptasia-x, vinegar, boiling water or just leaving the rock out in the open air for a couple of days(killing everything on it.)
Peppermint shrimp work well as long as they don't have a different food source they like better. It is also very important to get the correct shrimp as there is an imposter shrimp that doesn't feed on aiptasia that looks very similar. When you are buying the shrimp ask for L. wurdemanni. Do Not accept the shrimp if it is a L. californica.
Peppermints will also not attack a large aiptasia so these will have to be removed in another way. There is also no guarantee that the aiptasia will not release its seed into the water which they tend to do when in danger. This will cause more to pop up later.
The Copper banded butterfly's require an established tank to safely house one (preferably 6 months or longer). Some for whatever reason don't prefer aiptasia though (the upside here is that these ones are reef safe)
If you choose this method you risk the fish devouring other corals in your tank that you wanted to keep once it has eaten the aiptasia. And again, there is no guarantee that they won't release their seed into the water when attacked.
Aiptasia X is similar to the paste that I described above and it comes in a nifty little syringe with a straight and an angled head for getting at aiptasia in hard to reach places.
The downside here is the cost. At 20 dollars a tube it gets pretty costly, especially if you have a lot of aiptasia to treat. A jar of Mrs. Wages pickling lime costs about $4 at Wal-mart and you will have a lifetime supply.
Boiling water, vinegar and Joe's juice all have been known to work but as with most methods are very hit and miss. While one person says they had great success the next may say it didn't work at all.
Best of luck to you and good hunting!