20% draw injector 4gpm 10% sh

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Downstream ratio

The ratios given by manufacturers is usually the theoretical best case scenario of how much the injector can draw. As in, lowest rated flow rate (on a 2-4 gpm injector, they’ll rate it based on a 2gpm machine), no back pressure from long hoses, short soap tube, etc. In real life, they will draw a lot less. But @Innocentbystander is correct. Ratios don’t matter for most situations. If the growth on the siding is turning colors and starting to come off within 5 minutes or so, your mix is good. …