Not sure what your protien skimmer or canister are putting out but I would have to believe that your 90 gallon tank doesn't have enough turnover rate.
With just the bio wheel and the power head your only turning over 5.22 times per hour, do your canister and protien skimmer make up another 5 times per hour? Then I'd believe you would at least have enough water flow to keep the anemones happy.
So my first guess, and that is all it is, is just a guess, that they are looking for better water flow.
Second thought is that perhaps you don't have enough filtration for a 90 gallon unless you have plenty of liverock and live sand.
Third thought is that I still don't know how many watts your lighting is. Are there any numbers that you remember like 2x65 or something on those PC lights?
This is also assuming that your water is fine, alkalinity and calcium are good as well as the 0-ammonia, 0-nitrites and low nitrates. No heavy DOC's built up.
I'm not trying to burst your bubble or anything just looking for possibilities as to why they might be wandering all the time. For the most part I have 6 BTA's that don't move, a couple of others that move occationally.
Also:
rdursch Every two days with phytoplanton, brine and flake. Not enough? Wrong stuff?
I don't put much stock in feeding an anemone phytoplankton, they do use it from the water colum but its nothting that I would squirt into them. Brine isn't very good either if frozen or freeze dried.
I would feed them mysis shrimp, frozen plankton, chopped shrimp or krill, formula 1, just make sure the food is no larger than a pencil eraser. I also use Selcon or Zoecon as a vitamin suppliment on and in there food.
Thomas