[My tank has been running for about 18 months now and I'm starting to notice that my sandbed looks a little thin in places. I think I would like to add some sand to it, but I want to disturb my system as little as possible. I was thinking of adding the sand primarily under the internal filter box. I initally used a "live sand" from the LFS, but I don't think that's a good idea now because it will likely cause an amonia spike and who needs that. I'm thinking dry sand, but I'm not sure what kind and where to buy it. Anybody have any thoughts or suggestions?]