Sorry, I deleted my first post and almost all of the other along that line...lol
Anyhow I believed that because this is the only tank that I started with 100% dried rock, and they had to leaked out. I can't pin point any other reason, I always did the same method of setup. I make my own rodi water and salt mix and I'm extra cautious of what goes in my tank. But these rocks was acid soak, and neutralize. I even went a extra 3 months soak in bleach and vinegar. Then a fresh water soak and hitting them up with pressure wash. Still not fool proof, so that and my bad habbits of over feeding and nature just takes it course.