Anyone have sand over their gravel? Curious if this is not a good option or what have ya. I just added the sand to the main tank in a major restructuring and I kind of like the way the mix looks. I stired it slightly where there where a few pebbles showing through. My original plan was to eventually pull the gravel out but now I'm not sure. If this will build up bad gases then I will pull it. Wha cha tink?