This info is taken from "The Marine Aquarium" book:
Triffid, Glass or Rock Anemones (Aiptasia spp)
Triffid anemones are the proverbial wolves in sheep's clothing. They are beautiful creatures, so impressive and attractive to look at that they are often given priority treatment, only to multiply into a dangerous and unslightly plague! They have a prodigious sting capable of killing (as a prelude to eating) small fish; even larger fish can sustain a nasty injury. Reef tanks suffer particularly badly, for as the anemones spread amongst the polyps, corals, clams and other anemones they tend to sting everything they touch. As a result, if their neighbours are not killed, they will show the "burn" marks from having brushed against these fearsome predators.
One anemone can produce copious off-spring in a few weeks owing to an extremely rapid reproductive ability, especially if the tank is consistently overfed. Several months after that, a whole aquarium may be covered in a mass of these anemones if nothing is done to bring matters under control.
Triffid anemones have an elongated body stem lodged far down in a rock crevice or among a polyp colony, making it virtually impossible to remove. At the slightest disturbance it will disappear into the safety of it's inaccessible home. To make matters worse, if the whole animal is not destroyed, it can regenerate itself from a small piece of remaining tissue. They can also live in total darkness quite successfully, so check all water routes, especially pipes and other areas of limited access, when trying to eradicate the system.
Sorry for the essay I was bit bored so I thought I'd do some typing!!!
Speaking as someone who has suffered from these blighters and has tried different methods of getting rid of them, I now wouldn't recommend Joes Juice. It doesn't seem to keep very well (yes you can add water to it to make it viable again) but I find boiling water mixed with lemon juice works just as well and is a lot cheaper.
