[mps9506]

I would recomend Joe's Juice. Before Joe's Juice came on the market I used thick kalkwasser paste, but you have to be careful using that as it can burn nearby corals. Vinegar works well also. The reason I recomend Joe's Juice is it doesn't seem to negatively affect nearby corals. They might close up for a bit, but it won't harm them.
Even the little guys you have can be killed with Joe's Juice. Just try to get really close to the aiptsia mouth and squirt down into them. Might take two or three tries but they will go down.