Downstreamingredients : I'm stuck

Ok, so I got my new machine a few weeks back, 5.5 gpm, 3000 psi, Honda Motor. I have tried down streaming a few times (I’ve always softwashed with my roof pump) and I can’t get adequate results. My SH is 12.5% and it is fresh as it works thru my pump. I’m using a 5 gallon bucket, half water half SH and using the DS injector that came with the machine. Ive tried the injector at the reel instead of at the pump, I’ve gotten a better gun, I’ve tried everything I can think of. But it’s still requires a lot of spray to get the houses clean and the dwell time is 2 to 3 times what I’m used to. So the last thing left is the injector. I don’t know what it’s pulling, the only marking on it is “2:1”. Anyone have any idea what my issue is? Should I try a different injector? If so, which one?

get a small plastic bottle and time how long it takes to empty X amount in 1 minute using 1) hose only, 2) hose and gun only, 3) hose, gun and nozzle only. Draw rate should be slightly less each time but close. If draw rate is way off with experiments then you can deduce which is the culprit. 2.1 is a measurement in millimeter of the orifice in the injector. Blow in the barb and make sure ball is not stuck. when you suck on it you show get no air flow. No idea what injector came with the machine but the economy ones from Espec are garbage. Adjustable ones are garbage. I use General pump injectors. Others may be better but I experimented til I found what I liked and stopped.

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@Innocentbystander, so if the draw rate is similar for all tests, should I assume that its just a junk injector?

Not necessarily. It means that your gun and nozzle are not the problem. Have to narrow things down.

You say got a better gun? Hopefully minimum 12 gpm rating.

When i first started i use to water down my mix with 2 gallons of SH and rest water and a few squirts of dawn soap. It worked good when i was using the X-jet M5. Then i got sick of hauling around a bucket and dealing with that extra hose, so i decided to try downstreaming using same formula and found out quickly the mix wasnt coming out as strong so i was reapplying twice (wasting more time) so i decided to just fill the 5 gallon bucket with straight SH and havent looked back since. Some people are really scared of hurting plants, grass or other things but ive really only damaged 2 things and one was my fault for leaving the SH baking in the sun for way too long in the middle of the summer and the other one was for not covering those door handles with key pads on them. Just my 2 cents

Downstreaming straight 12.5% with soap would be my starting point on
slightly dirty stucco or drivit, or washing vinyl on a very cold day. I think
with the properly sized fixed general pump high draw injector, gun rated
at 12 gpm, fresh SH and a good soap surfactant like elemonator a 50/50
mix downstreamed should get you great results with a 5-7 minute dwell.
My opinion only, YMMV.

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You need to experiment to work out the draw rate of YOUR system - injector, hose length, nozzle (at 5.5gpm you want a #40 or 50, maybe even a 60 to get the lowest pressure possible) all make a difference. Then mix a batch of SH/Water/Detergent to suit.
If your system is drawing at 1 chemical to 5 water (1:5 or about 20%) and you want 1% SH on the house and your SH is 12% then mix it half SH & half water/detergent. There are many injectors out there and many are (theoretically) only 10% and even less in reality so you may need to add the detergent directly into the SH - but you won’t know the reality until you test YOUR system.


So I have a gp 20% highflow downstream injector. And a 16 hp vtwin motor and a gp 5.5 gpm pump belt drive. I am just getting started and my only question that I can’t seem to get answered is for downstreaming do I mix my sh and surfactant with water before I downstream it?? What’s best way to figure my ratios out? Everyone tells me to search and everyone’s responses are all different responses. Just want to know a good got formula that works for most everyone and then I will tweak it the way I need to.

What strength bleach are you buying?

The GP hi-draw injectors will pull more than standard injectors, but 20% is an ideal, theoretical figure, imo.

Start with a mix that works out to around 5% SH in the bucket. So if you’ve got 12.5% bleach, mix 2 gals SH to 3 gals water. If You’re using off the shelf 8.25% bleach, then do 3 gals SH and 2 gals water to start off. But remember that most stores don’t give you a full gallon of concentrated bleach.

Once you’ve figured out what it takes to get 5% SH in your bucket, then start experimenting. If the algae and mold are slow to change color and break down, then bump up the concentration a bit.

After awhile, you’ll get a feel for what situations require a heavier solution. You’ll also begin to account for temperature variables, age of the bleach, and so on.

OR, you could do like some guys, and just run straight SH + surfactant for everything. You’ve gotta be more vigilant about pre and post rinsing vegetation and other sensitive surfaces, but it takes the guesswork out. And on 90% of houses the growth just sloughs off in a minute or two…

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