Proportioner for 12v and DS Injector?

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Yes, this can be accomplished, using a proportioning injector:

Best injector on the planet and other fittings

Here’s one more video to celebrate me teaching @Innocentbystander something and I feel like bragging about it. And these really are the best injectors available.

And using a dual barb proportioning injector would allow you to keep your housewash surfactant separate from the bleach.