Today I bought a used Fluval EVO 13.5 to use as a QT and I need to clean it. I have no clue how to clean tanks and I need help with it. I took all the equipment out of it. I'm going to fill it with water and put some chemical in it but I don't know which one is the best (citric acid, bleach, vinegar?). Also, how do you remove the water/chemicals after you let it sit and clean the tank so it doesn't affect the tank later on?