bleach

How to Run the Pro Mixer XL (and the Rinse Step Most People Skip)

Updated Oct 21, 2026 Published Mar 21, 2025 Tim Cray 4 min read

Key takeaways

XL means 3/4 inch. Most 12V mixers run half-inch valves; the Pro Mixer XL runs 3/4 inch valves and check valves so flow does not choke down through the block.
Water stays wide open, always. For a house wash, bump soap on a little and set bleach around the 1 mark; for roofs and moss, open bleach wide for roughly a 50/50 mix.
Give a setting change two to three minutes. The new mix has to work through the pump and 200 ft of hose before you see it at the gun.
The rinse step is where mixers die. Turn soap off, switch the three-way valve to water, and leave the metering valve all the way open so water flushes the bleach leg instead of leaving concentrated SH in it.
Rebuild once a year. Check valves go in one to two years, bleach side first; pull it apart, clean off old sealant, reseal and fit fresh check valves.

In this guide

How to Run the Pro Mixer XL (and the Rinse Step Most People Skip) - Expert Power Wash

There are over a hundred Pro Mixer XLs out in the field now. The ones that fail early almost always fail for the same two reasons, and both are avoidable.

This covers what the XL actually is, how we set it for houses and roofs, the rinse step that most people get wrong, and the yearly maintenance that keeps it alive.

Why it is called XL

Most 12V soft wash mixers run half inch valves. Ours run 3/4 inch — valves and check valves both. There are three check valves in the system: one on water, one on soap, one on bleach.

The reason is flow. Every check valve and every metering body is a restriction. At half inch, you feel it. At 3/4, the chamber the liquid is being metered through is substantially bigger and the flow does not choke down the way it does on a smaller block. We tested both before settling on it.

Settings we actually use

Water stays wide open, all the time. Everything else is metered against it.

House wash: soap bumped on a little, bleach somewhere around the 1 mark. Good starting point, then adjust to the house.
Roofs, and Pacific Northwest moss: water wide open, bleach wide open. That gives roughly a 50/50 mix, which lands near 6% out of 12.5% SH. That is what our moss needs out here.

These are starting points, not gospel. Every job is different and the buildup is different. We keep a settings guide printed on the inside of the skid so nobody has to remember.

One thing that catches new operators out: after you change a setting, it takes two to three minutes for the new mix to reach the gun. It has to work through the pump and then 200 ft of hose. Do not keep cranking the bleach because nothing changed in the first thirty seconds.

The rinse step, which is the whole ballgame

This is where mixers die.

When you finish soft washing and switch to rinsing, here is the correct sequence:

Turn the soap off — you do not want soap pulled into the line on a rinse
Turn the three-way valve to water
Leave the metering valve all the way open

That last point confuses people. Opening it all the way is not turning your bleach on — you have already switched that leg to water. You want full flow through the block so it flushes properly.

Here is why it matters. The old way of doing this was to just turn the bleach off and pull water in through the water valve. That does rinse your block, your pump, your hose and your gun — but it never brings water into the bleach leg of the mixer. So that leg sits full of concentrated SH until the next job.

Our bleach out here is hot. We are often getting it at 13.5%, sometimes close to 14%. Leaving 14% sitting in a section of the mixer between jobs is how you get premature failure in exactly that part of the block, and it is why we build the rinse valve in rather than leaving it to technique.

If your mixer does not have a dedicated rinse valve, that is what a soft wash bleach rinse valve adds.

Yearly rebuild

Check valves are a wear item. They typically go in one to two years, and the bleach side goes first — water and soap side check valves rarely give trouble.

Rebuild the whole mixer about once a year:

Pull all the parts and fittings off
Scrub the old sealant and PTFE off with a soft bristle brush
Reseal everything
Reassemble with fresh check valves

Do that annually and you eliminate most of the breakdowns crews see in the field.

A blunt word about running this business

If you are not mechanical and you do not want to turn a wrench, you are going to have to learn quickly.

Bleach is corrosive. It kills parts. It works through seals. You will get leaks. That is not a defect in anybody's equipment, it is the nature of the chemical you have chosen to spray for a living. Preventative maintenance is what keeps you on jobs instead of in the shop.

Parts and mixers

Pro Mixer XL Custom 3/4 Soft Wash Mixer — the unit in this video
Precision Pro metering valves and replacement parts
Soft wash bleach rinse valve
All soft wash mixers and parts

Frequently asked questions

What makes the Pro Mixer XL different from other 12V soft wash mixers?

Most 12V soft wash mixers run half-inch valves. The Pro Mixer XL runs 3/4 inch valves and check valves, with three check valves in the system: one on water, one on soap, one on bleach. Every check valve and metering body is a restriction, and at 3/4 inch the chamber is substantially bigger so the flow does not choke down the way it does on a smaller block.

What are the Pro Mixer XL settings for a house wash?

Water stays wide open all the time and everything else is metered against it. For a house wash, bump the soap on a little and set bleach somewhere around the 1 mark. That is a starting point; adjust to the house.

What mixer settings do I use for roofs and moss?

For roofs and Pacific Northwest moss we run water wide open and bleach wide open. That gives roughly a 50/50 mix, which lands near 6% out of 12.5% SH. Every job and every buildup is different, so treat it as a starting point.

Why did nothing change after I adjusted the bleach on my soft wash mixer?

After you change a setting it takes two to three minutes for the new mix to reach the gun, because it has to work through the pump and then 200 ft of hose. Do not keep cranking the bleach because nothing changed in the first thirty seconds.

How do I rinse a soft wash mixer correctly after a job?

Turn the soap off, turn the three-way valve to water, and leave the metering valve all the way open. Opening it all the way is not turning your bleach on, since you have already switched that leg to water; you want full flow through the block so it flushes properly. Just turning the bleach off and pulling water through the water valve never brings water into the bleach leg, so that leg sits full of concentrated SH until the next job.

How often should I rebuild a soft wash mixer?

About once a year. Pull all the parts and fittings off, scrub the old sealant and PTFE off with a soft bristle brush, reseal everything and reassemble with fresh check valves. Check valves typically go in one to two years, and the bleach side goes first.

What if my mixer does not have a rinse valve?

A soft wash bleach rinse valve adds a dedicated rinse leg so water can flush the bleach side of the mixer between jobs. We build the rinse valve in rather than leaving it to technique, because bleach at 13.5% to 14% sitting in a section of the block is how you get premature failure in exactly that part.

Written by

Tim Cray

Owner, Expert Power Wash

Tim and Kristina ran their own pressure washing company for more than ten years on trailers, box trucks, flatbeds, vans and skids before Expert Power Wash started building equipment for other contractors. Today EPW has 300-plus builds working in the field and services pressure washing rigs in the Oregon City shop every day.