I get C from Sam's Club so the cost doesn't bother me at all. My problem is I was losing entire colonies that had been doing great for years, right next to colonies that were fine. Everybody kept telling me the brown dusting on them was a fungus & to dip but all my zoas are growing on rocks way too big to dip. I was looking for something to dose the entire tank, like Maracyn (or some kind of anti-bacterial/fungal that was safe for the entire tank), when I remembered that I read somewhere about dosing with Vitamin C & echinacea. Since echinacea comes in capsules that were a PITA to open individually & I didn't think the gelatin would be good for my tank, I decided to go with the C. I take it 2x/day, because it isn't stored in the cells, so that's why I dose 2x too. I figured, boosting their immune system with an antioxident might work & I think I might have fallen onto something good.