I have seen the other dirt and sand posts but didn't quite find the info I was looking for in it that is a concern for us. Currently we have Panda Corries in a tank with gravel that seems to be giving them issues and we really like these little guys, we are making plans to set up a tank with a sand substrate. We also would like to make this a planted tank. Our current tank has dirt with clay then Gravel as a cap. We are thinking of doing dirt with sand on top. Question is will the dirt and other organic matter in it (like twigs, and other items found in organic soil) mix into the sand and end up on top/poking through giving the corries some issues? Also how thick of a lair of sand? I have read different reports, some say make it thicker so that you don't have to worry about the corries digging around and mixing your substrates, others say to make it thinner as the thicker sand will cause more gas build up under the substrate, which this could cause a problem if a bubble of this build up comes up and hits a corry in the face. I am also researching what type of sand to use, seems a lot of folks use pool filter sand, anyone have experience with this and corries? The other tank mates will most likely be our female Beta, and narite snail, not sure if this is a tank set up you would want to put any MTS into.