Get the exact SH mix for your Xjet or downstream injector — enter your ratio, bucket size, and target surface concentration
Whether you're running a standard downstream injector or an Xjet proportioner, the fundamental principle is the same: your machine dilutes whatever is in your bucket before it hits the surface. The ratio tells you exactly how much dilution happens at the tip.
A 1:1 ratio means the proportioner draws 1 part chemical for every 1 part machine water — so your bucket concentration gets cut in half at the surface. A 5:1 ratio means 5 parts water per 1 part chemical, dividing your bucket concentration by 6. The formula is simple:
So if your bucket has straight 12.5% SH and you're running a 10:1 tip, you're hitting the surface at 12.5 ÷ 11 ≈ 1.14% — a solid house wash mix. Swap to a 1:1 tip with the same bucket and you're pushing 12.5 ÷ 2 = 6.25% — useful for heavy roof moss.
A downstream injector sits between the pump and the gun, pulling chemical from a tank through a fixed metering orifice. Most downstream injectors run around 10:1, though this varies by machine and can drift with pressure changes.
An Xjet (or M5 Xjet) is a proportioner that attaches to the end of your wand. You swap color-coded tips to change the ratio — common options are 1:1, 2:1, 5:1, and 10:1. Because it operates at lower pressure (after the gun), it's more consistent and lets you apply higher concentrations without needing a 12V pump.
SH alone will run off fast. Always add a surfactant (like Elemonator or dish soap as a budget option) to your bucket so the mix dwells on the surface long enough to kill organics. Typical rate is 1–3 oz of surfactant per gallon of mix in the bucket.
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Water parts : 1 part chemical drawn from bucket
12.5% is standard bulk SH; pool bleach is ~10%; household bleach is ~6%
Divide your bucket concentration by (your Xjet ratio + 1). For example, straight 12.5% SH through a 10:1 tip gives 12.5 ÷ 11 ≈ 1.14% at the surface. To work backwards from a target surface concentration, multiply the target by (ratio + 1) — that's what concentration you need in the bucket.
Most downstream injectors run around 10:1. With straight 12.5% SH in the tank, a 10:1 injector delivers roughly 1.14% SH at the surface — a solid concentration for removing algae, mold, and mildew from vinyl siding, brick, and stucco.
A downstream injector is installed between the pump and the gun and pulls chemical at a fixed ratio (usually 10:1). An Xjet is a proportioner that attaches to the end of your wand — you swap color-coded tips to change the ratio (1:1, 2:1, 5:1, 10:1). The Xjet is more versatile and lets you apply higher concentrations without a 12V pump, making it popular for roof cleaning.
Roof cleaning typically targets 1.5%–3% SH at the surface. With a 1:1 Xjet tip and straight 12.5% SH, you get 6.25% — more than enough for heavy moss. For a lighter 2% application, a 5:1 tip with straight 12.5% SH works out to about 2.08%. Always add a surfactant to extend dwell time on the roof surface.
Yes. The calculator works for any chemical where you know the source concentration percentage. Just enter the concentration of your chemical in the source field — the dilution math is the same regardless of what you're mixing.
Most professionals use 12.5% sodium hypochlorite (SH), available from pool supply stores or chemical distributors. Pool shock runs around 10–12%, and household bleach is only 6–8% — which limits how strong a mix you can push through a downstream injector.
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