Figuring Downstream Bleach Dilutions
I am often asked about figuring downstream bleach dilutions when pressure washing. I have never really cared to know what the exact precise percentage of bleach to water is coming out of my gun. What I am concerned with, is one important fact, is the bleach mix strong enough to change the color of the organic stains or not. If it isn’t then I know I need to use my dedicated pump, like our Kingslinger Soft Wash System, or a pump up sprayer. Always remember, that all a Soft Wash System is, is a pump up sprayer on steroids. It allows you to get a stronger mix, like with a pump up sprayer, without having to re-fill the canister and continuously have to manually pump air into the sprayer.
The strongest bleach solution you can usually achieve using a General Pump Downstream Injector is around .8-10%. If you have green algae which is easy to remove, then downstreaming will work for that. Once you get in to the darker and black mildew stains, then you need a stronger mix than downstreaming can deliver. A pump up sprayer or soft wash system that can get you 20% or higher, is great for that. For Roof Cleaning, you definitely need stronger mix ratios then what downstreaming can deliver.
If you are one that likes figuring downstream bleach dilutions, then here is a bucket method test you can perform. Also be sure to check out my Online Pressure Washing Video School if you are starting a pressure washing business.
How to manually figure out your dilution ratio on your pressure washer.
Check your flow rate on your pressure washer for 1 minute to see how many GPM your pressure washer is putting out. Use a container that measures gallons along the side of it and fill the container up for 1 minute and try to make sure to not allow any water to get out of the container as you are doing this test. (Ideally you will want to do this test with your rinse tip on the end of your wand)
If your container doesn’t have the markings, or a graduated scale, then you can manually mark them by using a measuring a cup to pour desired amounts into the container, and then mark them.
Test your upstream or downstream injector by getting a metering jug that measures ounces and fill it with water and put your soap line into the metering jug and draw the water for 1 minute. This will allow you to see how many ounces your soap injector is drawing in a minute.
Doing a little math
If you have a 5 GPM pressure washer then you will do the following math to figure out your dilution ratio on your pressure washer.
5 X 128 (128 ounces in 1 gallon)=640 ounces
Draw rate in a minute: 40 ounces
640/40= 16 total parts, 15 parts water to 1 part chemical, so your dilution ratio would be 15:1 or some in the industry will say 1:15.
I am also including a link to a calculator that you can play around with, and may help you as well.