I have been to his lectures and I actually really like the guy (can't remember his name right now) but the fact of the matter is, it's just dirt. I like his reefkeeping philosophy, but when I read sales material that states it even cures lateral line disease, I just can't help but be cynical.
No telling what sort of gasses amass in layers of that either. When someone takes the initiative to call their product "Miracle" anything, the hairs on my neck stand up.
However, one thing to note is that he does recommend changing it out at periodic intervals, just like I would with a sand bed. Coral sand is much cheaper, provides the same minerals, and I believe less risk. And this comes from me, a guy who put worm castings sand, and stream bed material from the stream on my property into my FW planted tank.
I don't want to knock Miracle Mud or it's purveyor, but I seriously wouldn't put it in my reef tank. And again, let me state for the record, I really like him as a person, his philosophy of reefkeeping, just not that product line.
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