I have three RBTA in my 120 gal LPS/SPS tank. One of mine did move but not much from its original spot. As far as flow is concern, I don't think it is a problem, mine seems to expand out more with the alternate flow. When I got them, they were 3-4 inches in diameter. Now, they expand to closer to 8 inches. In the long term, I will have to get a tank dedicated to these beautiful anemones just because I want them to split and take over the tank. But right now, I am happy with how they are behaving.