Birds nests are extremely finicky corals. One day theyre fine, the next, whammo, rtn. Ive never had the greatest luck with them either,. Theyre very demanding as far as water flow goes, positioning in the tank, lighting and >co-habitation with other corals< They dont seem to do well in a mixed reef especially if theres leathers in the area. Theyed probably do better in an sps only tank given the right conditions.