Understanding downstream rates


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?


For me personally a 1% mix is pretty hott for your standard house wash. Just tinker and use what works for you. It’s nice to see you’ve done your home work & tested your injectors actual draw rate. It will only help u in the long run


Thanks for the response, and i was kind of expecting/hoping for that answer.
Yes i over analyze the crap out of everything!! LOL! I just want to make sure im not missing anything, damaging anything, or wasting money. I feel that i can dilute the 12.5% some with a little more math and save a little. Im not being cheap, but i dont want to use any more on a property than necessary.
Possibly 0.50% is an effective rate on vinyl siding? I have 27 more apartment complexes coming up and im just trying to get everything lined out as i go.


don’t overthink it
fill a 5 gallon bucket with just water
place your injector line.
turn on pw.
DS, for a minute.
turn off, pull line from bucket
fill bucket with a measure jar.
and now you know how much you pulling
Now do the math


Yes sir, as I said in the first post, I’ve done that, probably 20 times. I know my draw and flow rates, the questions m having are on dilution rates and what % should be hitting the siding


Dude, exhausting goodwill here by asking inane questions will serve you badly. PWRA may very well be your best source of knowledge. SO, having stated this, I should inform you that there are very many elements that determine the answer to ths inane query:: ambient temperature; surface; depth of infection by offending bacteria, humidity/chance of rain, whether you woke up on the right side or left side, or even at all… OK, maybe not the last one but you et the picture.

\YOU WANT A DWELL TIME OF 3-5 MINUTES before the offending organism disappears (or at least changes color so that you can rinse away). THAT’S IT. ALL THE REST IS SUPERFLUOUS.

Stop concerning yourself with minutia, and devote yourself to getting work. The minutia will take care of itself.



Um. Huh?

Asking questions here will serve me badly?

Ok. My apologies.

I’ll just go back to lurking. I wish I could understand why people try to make new guys look bad and stupid. I’m a perfectionist. I try my best to do everything above and beyond. I’m sorry if experimenting in someone’s property seems stupid to me, but I guess if that’s your recommendation, I’m on it. I don’t feel anything on a customers property is “superfluous “.


My mix
3.5 gl of SH
.5 of arm and hammer
1gl of surfactant.

Everyones mix is different.
The more houses you do the better you will get at your mixes when you see a home.

Dont overthink it, dont be square.
Owner operators aint.
Think outside the box.


Didn’t see anything wrong with your question & get where you are coming from 100%. Keep grinding & best of luck!


Nobody is out to embarrass you or to make you “look bad and stupid”, but instead enable you to look at the bigger picture: there are far too many factors with which to concern yourself. Downstream rates ARE ALL CONTINGIENT UPON THOSE OTHER FACTORS, Nothing is as simple as we all think when we get started. I joined this forum about a year ago (I began my business July 31, 2017), and what I’ve shared with you IS THE EXPERIENCE OF A NEWBIE. Good luck! Hell, I don’t downstream at all: I’m an XJetter.: HOW 'BOUT THAT FOR A KICK IN THE $SS!!??


It wasn’t the information you gave, but the fact you told me my questions were stupid and unnecessary that was irritating. I don’t judge or degrade people, if there is no gain there is no point. I do appreciate the information, and I bought an xjet but don’t care for it. Carrying a bucket around seems dangerous and clumsy to me. I’d rather keep everything on my trailer and only have one hose to worry about!! Experience may change my mind someday though.


@MrSparkleVA is a great guy with a way of words ! Dont think too hard on it. Basically in a nutshell hes saying just do what works, and forget the specifics. I second this approach. It’s one I learned from @Nashvillewash hahahaha.


TBH I think having a ladder that’s not tied off, working on a wet roof with no fall protection, and applying chemicals in shorts is stupid, but I’d never take time out of you day to tell you that!!! :rofl::rofl::rofl:


I wish my mind worked like that!!!


Haha it’s not too late my friend ! Hahahaha.


You use 1 gallon of surfactant in a 5gallon mix?


Yes i do.
Or maybe .5
I eye ball it.
But 3.5 gl of SH

I hate wasting time.
SH is cheap, my time is not


You’re a man after my own heart. I like knowing all this stuff too. I’m actually surprised that 2.1 injector not pulling stronger. My 4gpm pulls about 9-1 and my 8.5 about 18-1. Most people with 5’s pull around 12-1 so you may want to try another injector. Your’s may be getting worn or check your incoming filter and make sure no debris in it. Those little backflow balls get stuck all the time. First thing I do is pull those out.

With my 4 I usually go about 50-60 percent SH, rest water and soap - with 8.5 go about 80% SH with water and soap for the average dirty property. If really really bad will pull straight SH but that only happens about once per month. I’ve found that 90% of the time a mix of about .6% net is plenty. And there is a difference in surfactants. Different ones do better on different things.


I am confused too. The Arm and Hammer is all soap or is it a mixed solution? You add both the A&H and a second surfact?


I get that SH is cheap but that’s got to be one soapy mix with 1gallon of surfactant. Maybe I don’t put enough in but I’m only at around 5-6 ounces in a 5gal mix.