Well, I know that there have been a lot of threads lately about simple sand substrates, but I have an issue that I have yet to read about... So, I bought basic playsand from Home Depot and rinsed it using a paint strainer, and have used it in 5 tanks. In the first and third tank I used it in, it worked great, and stayed an aesthetically pleasing tan colour; however, with all of the others, it began smelling rather foul, turned grey, and started killing plants all within a few weeks after being put in the tank. I'm assuming it's bacteria, as the smell is somewhat sulfuric, but I can't tell why it worked in the other tanks... So, any ideas? I'm at a complete loss here...