Just an opinion but I like to 'cure' any new sand that I put in my tank. This greatly reduces the time it takes to settle and it reduces the risk of the new sand causing a precipitation event.
This is the situation:
When Calcium is supersaturated like it in is a reef tank all that is needed is a small crystal of Calcium carbonate and the Calcium will bond with Carbonate to grow the crystal.
The only thing stopping this reaction in our tanks is Magnesium. When Magnesium bonds onto the growing Calcium carbonate crystal Calcium is blocked from using the crystal to precipitate onto. This Magnesium is permanently removed from the water column and the Magnesium level is dropped by one molecule. The Mg
drop caused by Mg
coating a single grain of sand is insignificant.
Adding a handful of sand can actually produce a measureable drop in Mg
depending on the tank volume.
A whole bag of fine grained dry aragonite dust can theoretically drop the Mg
level below the saturation level. If this happens then there's nothing that will stop the Calcium carbonate crystals from growing until the Calcium level drops below saturation levels.
It's the final precipitation of Calcium carbonate that can form a cement like coating on tank walls, rocks, etc. During this process PH
will drop rapidly, Ca
and Magnesium will drop to useless levels.
Because of this, I strongly encourage growing a coating of bacteria over the sand grains before adding it to an established aquarium.
This precipitation event doesn't always happen but the risk is high.
Add 3 gallons of tank water to a 5 or 6 gallon bucket (old salt bucket). Slowly add 25 pounds of sand and sprinkle some flake food in it. After a week add the sand to the tank.
This doesn't eliminate the cloud, but it adds a bacterial coat to most of the sand grains. This lets the dust settle much faster and it reduces the calcium precipitation that happens when you add dry aragonite to the tank. If you need to add more sand either get more buckets or just repeat the process.
Add no more than 1/2" of sand to a live sand bed a week.