I had a huge aiptasia infestation when I first set up my tank, came as a bonus with the live rock I started with
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I started with Joes Juice and found that it would erradicate them on application, but, IME within a couple of weeks they would return in the same place. Also, regardless of how careful you are, I find it messy.
Boiling water worked better for me but it had to be boiling hot to be most effective. Problem here was lots of them I couldn't reach in my rockwork and so they would quickly multiply again.
Finally enlisted help and purchased a peppermint shrimp. He had the problem wiped out within 2 weeks, and I probably had 50-60 large and small ones that I could see to count. I've never seen a shrimp grow so fast
Now he is one of my favourite critters, he is out all the time, very active, and there has not been one aiptasia in months
