I have just purchased a 90 gallon tank and put 40 lbs of Caribsea seafloor special grade sand into it. It could be spread to cover the entire bottom but only thinly, so I have to put something more in. Should I be putting another 40 lbs of this, or I was also considering 40 lbs of Caribsea ocean direct live sand, spreading the argonite to cover the whole bottom and then putting the live sand on top. The argonite is supposed to be good for reducing nitrates, but I am wondering if it will still do so covered by layer of sand....the sand is supposed to be good for beneficial bacteria and burrowing inverts, they would appreciate a layer on top?
The finer grade sand will sink under the coarser grade sand as soon as you put any current in the tank. You're better off sticking with one type of substrate.
I agree with Stussi's comment. In addition, as far as claims being made by CaribSea about better nitrate handling, better pH stabilization or better whatever, I and many others on a host of forums have a hard time believing the marketing hype. Its like trying to believe that one company's biological filter media is 10x better than the competing brand. If you like the color and texture of the CaribSea you bought, keep with it. Some people will mix colors of same granule sized sands to achieve a certain color. At the end of the day, CaribSea is not going to perform much differently than a $5 bag of 50lb playsand at your local big box store, or pool filter sand. Nitrifying bacteria will grow everywhere in your tank and sand is a great source with it's small particle size for bacteria adhesion - like a fluidized bed that has suspended fine silica sand in it and has terrific biological activity.
My apologies for not noticing this thread was in saltwater.