I ended up getting a different purple mag.
I drove 200 kms to check them and it's one of those places where the staff is not very knowledgeble about the animals they are selling.
The anemone tank had absolutely no visible water movement, but all the anemones had their mouth closed. They had been there for over a week.
I chose the one with the foot on the glass. It was one of the smallest and it didn't look as sad as the others. The girl took it out in 2 seconds.
I stopped by the drugstore to get cypro and I drip acclimated it for a hour.
By this time the mouth was a bit open.
I had turned the UV on on the tank and I had replaced the carbon.
There are around 30 nems in the tank and I wanted to reduce the chemical impact of their presence on the new arrival and on the other hand reduced the odds of the new one infecting the others.
Pumps off and in went the mag on top of a small rock. I never saw a nem attach to a rock so fast, 5 seconds at most.
This morning it was still in the same place with the mouth tightly close.
The female clownfish has been very curious about it but it hasn't touched it yet. It's a good house in a bad area I guess.
My plan in to give it a week or so to adjust and then slowly move it closer and closer to the BTA's.