I know, I know… Its been beat to death, and ive searched, researched, read and read again, but i still have a few questions for the pros. From what i see, downstream injectors are refered to in at least 3 different ways. Some are refered to as “high draw 20%” this seem impossible to me, as this would equal 1 gallon of draw per 4 gallons of flow, 1 gallon of 5 = 20%. Maybe they actually mean 20 to 1 instead of 20%. Im using one labeled with “2.1” which ii understand is the size of the orfice (2.1mm) with my 5 gpm machine. I have measured the rate and flow as 1 gallon draw per 18 gallons of flow. Using fresh 12.5 SH on this injector im getting GREAT results on the apartment complexes ive been cleaning. Now, most of the recomendations ive read call for roughly 1% SH on vinyl siding, but 18 to 1 rate is no where NEAR 1%. But im still getting great results, so maybe im missing something?

Here is my logic,

One gallon of 12.5% mixed with 1 gallon of water = 6.25%

mix that with 2 more gallons of water = 3.125%

mix that with 4 more gallons of water = 1.5625%

mix that with 8 more gallons of water = 0.78125%

Now this is 16 gallons total, including the original gallon of SH, and the percentage is already down to 0.78%, add 2 more gallons to get to my 18 to 1 ratio, and its below 0.75%.

Most things ive read say to dilute the SH before downstreaming it, at this rate you would be closer to .50%

Am i missing something, or is the SH just alot more effective than some people are letting on?