I “feel” I notice improvement. At 40$ for a bottle that will supplement 2 tanks, daily, for over a year, why notI started a few months ago and I swear most of my coral reacted in a positive way. I get better pe on my gonis yeah, but my euphyllia and everything else too. I notice the sweeper tentacles on my brain coral reached further. I wouldn't operate without it even if I didn't have gonis.