I’m not familiar with the ST-601… what was the reason for buying it? Did someone recommend it?
If you want to softwash you need a downstream injector:
http://pressuretek.com/gphidrinkit.html
Call Bob (or ask IB or racer or someone) and ask which GPM he recommends for your machine, generally people use a GPM rated lower than their machine so that more soap will be pulled.
Go to the pool section of walmart and buy chlorinating liquid, which is 10% Sodium Hypochlorite (bleach).
They sell it in packs of two for even cheaper: This is the strongest you will find it outside of a pool store or a chemical distributor. If your walmart doesn’t have it, get 8.25% bleach off the shelf (check the label). You can get 12.5% from a chemical supplier, or maybe a pool store, but you usually have to buy it in bulk. If you decide to keep softwashing, you will probably want to start getting it in bulk, especially if you start doing roofs.
Put two gallons of bleach, 3 gallons of water, and 4-5 oz. of soap (elemonator) in a five gallon bucket. You can adjust the bleach up if needed, but that is a general starting point.
I’m assuming you will be using the M5DS, so drop your injector tube into the 5 gallon bucket and soap the house. Then pull the tube, drop it in your water tank, and rinse the house. You can get fancy by buying one of these three way valves, so instead of pulling the tube out each time, you just flip the valve.
http://pressuretek.com/3way1pobava.html
If you want to get even fancier, you can hook up a remote control so that you can change the source without walking back to the truck.
That’s downstreaming with a M5DS.
Downstreaming with a jrod is slightly different, but i’ll leave that out for now since you are going to use a M5DS. Let me know if you want me to explain it, or if you have any other questions.