aiptasiax is fine, kalk paste works well for me too. After you hit them with either, wait a few minutes and then see if you can siphon them out. Even if it doesn't kill them, it does tend to stun them to where they lose their grip on the rock. Just don't break them into pieces when doing so. I've used airline hose before (trying to not to pull too much water out of the tank between water changes). When you do so, sometimes they will get stuck on the hose and stop the siphon. If you then lift it up slowly, you can drop the end in your net, and then just flush them. They can regenerate from almost nothing, so if you siphon after "the kill" it can help them from coming back.