<a href=showthread.php?s=&postid=10099595#post10099595 target=_blank>Originally posted</a> by fambrough
I just did this. I added some fine grained sand to a tank that has had only coarse grain. My motivation was making a more suitable substrate for detritivores and denitrification. I was adding dry sand to live sand. My suggestions are three part. One, you have to soak and stir the sand to remove/float organic contaminates. Use mixed salt water of the same specific gravity as your tank water to do this. Two, remove some tank water--the sand will add volume. Three, use a zig lock bag to add the sand: partially fill the bag with new sand. Seal it. Lower it to the bottom of your tank. Open it and gently pour the sand onto your existing substrate. This will minimize the cloud of small particulate matter. I genlty mixed the my substrates. If you already have a fine grained substrate in place, you may not want to do that. I also added a cup of sand from my more established tank to help seed the new stuff.
Best of luck,
Ben