It is best to remove or pump out all or the majority of the waste product or residual liquid fuel from the tank first. Add the diluted degassing product to the tank. You want to use a mechanical pressure sprayer that “washes the air” and the insides of the tank well.

This should have a suction pump which will suck the materials through the pipe drain on the tank so it will suck it from the bottom and back up to the top in a circular motion making the whole tank like a large “washing machine.”

The idea is to really wash the inside of the tank including the inside top! Circulate this within the tank for at least 12 to 24 hours. If the waste residuals are heavier you may need to re-rinse with about half the original amount of product. To finish, drain the tanks and re-rinse the tank insides well with plain water depending upon how clean you need it to complete.
We often recommend an airless pump for these applications. The same type you would use in painting, only you are “painting” with a cleaning chemical. Sherwin Williams, Home Depot, Loews and Sears are good places for these. For larger, heavy duty tank cleaning jobs we often recommend products made by Gamajet® Cleaning Systems or Cloud Company.
Example 1 Tank Degassing:
Degassing and light degreasing of twelve generator tanks. Each tank is about 1,555 liters in volume or about 410 gallons. Total of between 4,932 to 5,000 gallons of tank space to degas and degrease. Estimate about 10 gallons of CS1 Super Concentrate. Dilute the CS1 at a ratio of up to 60 to 1 for this use. That’s 1 gallon of CS1 and approximately 59 gallons of water. This will total about 600 gallons of diluted product. Divide this between each tank and use about 50 gallons of diluted product per tank. Follow application directions. We are using CS1 because of it’s degassing ability. Microbes are optional. If using microbes no more than ½ lbs. per 10 gallons total of Super Concentrate should be required.
Example 2 Tank Degassing:
Degassing and cleaning a 1000 gallon diesel tank. The diesel product has been pumped out. Estimate 10% of the tank volume. This is 100 gallons of product. Take 2 gallons of CS1 Super Concentrate and add between ¼ to ½ lbs of blend AB microbes total to this. Dilute up 50 to 60 parts with water yielding between 100 to 120 gallons of diluted ready to use product. Follow application directions.