If your heating oil tank is filled with sludge, clean it to ensure that your heating system works properly. Although it is not recommended that you clean your oil tank yourself, if you are handy, you can accomplish the job without spending a lot of money to hire a professional contractor.
Place a disposable container, such as a coffee can, under the drain valve of your oil tank, and drain any remaining oil from the tank by opening the valve.
When the tank is empty, put a lid on the filled container, and put it aside.
Place a new empty container under the drain, and spray water into the oil tank with a water hose until the liquids that drain out are clear. Replace the drain cap on the tank.
Open the fill cap on your oil tank, and pour 1 cup of trisodium phosphate per every 5 gallons of water until the tank is full.
Put an air hose inside the tank, and push it through until it hits the bottom.
Turn on the pump, and allow it to agitate the solution for at least 12 hours.
Place a receptacle under the drain of the tank, open the drain, and drain the solution. Spray the inside of the tank with a hose until the liquids run clear.
Pour 3 gallons of denatured alcohol inside the tank. Try to get the alcohol to reach as many of the surface walls of the tank as you can by pouring it at different angles.
Insert the air hose into the tank, and turn it on to help dry the alcohol and absorb any remaining moisture inside the tank.
Replace the drain cap, and refuel the oil tank.