Why does the tank under our lab sink SMELL ?!?!

If you have a neutralization tank containing limestone in your lab, smells can occur if biologic media has been introduced to the tank. This could be as simple as someone pouring coffee or left over soup down the drain. If the smell persists, you can put some bleach down the drain. But more likely you will have to remove the limestone; clean the tank; and recharge with limestone. (Check your local environmental regulation for proper disposal.) Then put a big sign over the lab sink that states “NO FOOD or DRINK SHOULD BE PUT DOWN THIS DRAIN!!!!!” (The penalty you choose is up to local lab management.)  To learn more about neutralization: www.scientificplastics.com