My freshwater tanks have aragonite 95% with 5% black sand. I love the stuff!
I found this on another forum:
"Aragonite, which is unique to just CaribSea substrates, maintains the high pH African Cichlids need without the constant addition of chemicals. When the pH in your aquarium falls below 8.2, Aragonite snaps into action, breaking down into calcium (great for water hardness), carbonate (your buffer), and various beneficial trace elements like Magnesium. Your pH comes back up and the tank stays healthy, all without ever adding a single chemical. Other types of calcium carbonate don't react until the pH is in the mid 7's. In fact, Aragonite holds the highest pH of any gravel or sand, and has up to 30 times the buffering capacity of Dolomite, Calcite ("crushed corals"), or Oyster shell! Plus, unlike ordinary substrates, Aragonite never needs replacement, buffering automatically for the life of an aquarium. Eco-Complete™ for African Cichlids has a unique composition that re-creates the African Rift Lake environment in your aquarium.
In addition to maintaing the pH of your African cichlid aquarium, Eco-Complete™ for African Cichlids is also high capacity bio-filter. Aragonite is extremely porous, about 20,000 square inches of surface area per cubic inch! Imagine the beneficial bacteria population you can maintain with it. This is why Aragonite is unsurpassed in reducing nitrates, nitrites, and ammonia, allowing a bio-load many times greater than other substrates. You would have to buy 4 bags of ordinary gravel to equal the surface area available for water purifying bacteria in this one bag of Eco-Complete™ African Cichlid Substrate!"
