I'm not too knowledgeable about substrates, but I think using three inches of sand might be a bad idea because of how it can compact and easily form anaerobic pockets. I've used sand in tanks before, but never put down more than about 1/2".
Then again, maybe you could have a deeper layer than 1" if you had burrowers in your tank. Malaysian trumpet snails come to mind, but I've read that they don't actually burrow too deeply - maybe 1" at most. I've seen freshwater mussels at a LFS.
The other problem with MTS's is that they are carnivorous - not that they'll actively seek out moving fish and attack them, but they have a reputation for going after eggs. So if your intentions were to breed these rams, MTS's might not be good to keep in the same tank.
Hopefully, somebody who knows more will chime in on this one. I've only ever used a very thin layer of sand and specifically for non-planted purposes.
-Naomi