Killing Aiptasia, Xenia, etc.

using sodium hydroxide to kill annoyingly fast growing anemones and corals

    The quickest and easiest way to target kill just about anything in a reef tank is with NaOH (aka "lye"). Simply mix 2 tsp of NaOH (lye), with 2 tsp Kalkwasser (calcium hydroxide) in 100ml of distilled water. To use the solution, draw it into a syringe (preferably one with a dosing needle). Turn off all the pumps and water flow in the tank. Using the syringe, squirt the NaOH/Kalk solution onto the aiptasia/xenia/turf algae (or whatever you're trying to kill). Make sure to keep the solution mixed by periodically shaking the syringe. Be careful not to hit anything else with this solution as it will kill anything it touches. Keep the pumps off for an hour. WARNING: Be VERY CAREFUL with NaOH. It is extremely corrosive! It will also heat up temporarily upon mixing it with water. Mix it in a glass container and always use gloves when working with NaOH! You can make the solution stronger by making it more concentrated (i.e. 1 tbsp NaOh and 1 tsp Kalk in 100ml of water). 

Note for Xenia: Dying and dead Xenia can release a lot of toxins into the water. Once you've killed them with the NaOH/Kalk solution, it would be wise to use a power head or turkey baster to blow off the dead/dying Xenia and remove as much of it from the tank as you can.