Here is a quick and easy bleach calculator.
Say you have the ol’ 26 gallon tank from Northern Tool.
And you have 10% SH that you bought from Walmart or something.
And for this example we are softwashing a roof with a gentle mix of around 2%.
Simply input desired strength at 2%.
Current % is 10%.
Tank Size is 26 gallons.
y voila! We need about:
5.2 gallons of bleach
20.8 gallons of water
And we are good to start washing!