I have had really positive results with Berghia nudibranchs. They did a really good job at keeping the aiptasia under control and getting inbetween the zoo poyps where it is hard to treat etc. YOu do need a fair number though before you notice a difference. Unfortunatley I lost mine when I moved
. I would like to get more too, but now that coralscaping is gone, I reallly don't know where to find them.