|Special tank cleaning device|
We have 2 large plastic tanks, and they're easily cleaned with a small wheeled tank cleaner (I think we should name it WALL-E Jr.). It's hooked up to a pump via the top and bottom valves of the tank, and it blasts the entire tank with jets of peroxicarb and citric acid solutions.
A similar device is used to clean barrels. Some of our wine will go into new oak barrels (most are French oak, made in France, and shipped to our winery) while some will go into neutral (aka re-used) oak.
We hook the barrel cleaner to the power washer hose and blast the inside of re-used barrels with scalding hot water. The water and steam sterilize the barrels and wash away the tartaric acid solution (we store the barrels "wet" to keep the wood from drying out and leaking. They're filled with a tartaric acid and SO2 solution).