Choosing a surface cleaner for 4 gpm

I just purchased a 4200 psi 4 gpm pressure washer and want to start a small business what surface cleaner should I purchase for drive ways I have been looking at a 16 in whisper wash but the minimum gpm is 4 and I’m scared that it will be slow any suggestions?

The 16 inch Whisper Wash would be a great choice for your 4 gpm unit. Some have even pushed it to 19 inch if they had an upcoming plan of upgrading to 5.5 or 8 gpm and just had to work a little slower in the meantime. With a 16 inch paired with a 4 gpm, you should be able to move fairly quickly. In other words, 4 inches per gpm is a guideline, not a rule.

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Thanks for the help any other brand that you think might be better?

I hear Mosmatic is also great although they’re generally more expensive. No firsthand experience though. I absolutely love my Whisper Wash Ultra 19 for the 8 gpm unit I have and wouldn’t change a thing about it. If I had a 4 gpm unit with plans of sticking with it for a while, then Whisper Wash Ultra 16 would be my top choice. Very reasonably priced for what it is, too. @dcbrock has had both 16 and 19, so maybe he can chime.

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Thanks so much


Hit me up, I’ll get you set up with a surface cleaner.

We have BE, WW and SE brands. I’d recommend WW first.

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I recently purchased a 4 GPM packaged with a 24" surface cleaner. It was a local package deal from Hotsy. I have used a few times already and it works great. I know it is a little big, but I just go a little slower and clean more surface.

I started with a 4gpm 4000psi hot water skid and an whisper wash ultra 16". I used it for a few jobs but seemed like I could only get 800sqft an hour. I did a large driveway about 6000sqft and it took me all day going over it twice. I should’ve pretreated or post treated the driveway but that being said I sold that setup and am building a 8gpm unit. I recently purchased a whisper wash 19" 4 tip surface cleaner and its night and day difference. If you plan on upgrading at some point get a 19" like others have said and work slower, it will cost less in the long run. I like whisper wash the best.

I have the 19" and 16" WW for my 4 gpm. I’ve been using the 19" for years and it worked great. The 16" definitely has more force. I would recommend the 16" for the 4gpm. Pre-treating is the secret to getting the really bad stuff clean. Pre-treat with a strong enough mix and you can use any size. Get a roof pump and use it for concrete and there isn’t any driveway you can’t clean.

What chemical and what’s a roof pump


The difference between post treating vs not post treating

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Which chemical?

3-5% strength of bleach mixed with water in a pump sprayer is what I roll with. Concrete was still wet here but, when it dries it’s even better.

Thanks for the help

Bleach or, Sodium Hypochlorite, will be the most used chemical in pressure washing. House washing, roof washing, concrete, brick, etc. Almost anything that has organics on it will require SH to properly clean. Most buy it in 55 gallon drums or even 275 gallon totes if that tells you anything. There are also other chems we use. Oil or grease stains you’d go for a degreaser. Rust stains you’d go for an acid. Study up on different chems and what they’re used for.

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Awesome thanks

Good grief, that’s roof mix. I just use my normal housewash strength and seems to work fine.

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Roof pump is a dedicated pump and pulls from a tank. I call it a roof pump because most people use them to clean roofs. They’re also called softwash systems. I use this one.

That’s weird,…800 sq ft in an hour. I can do a little over 700 sq ft in twenty minutes with my 4/4 and 20” NorthStar surface cleaner. And that’s making a double pass and then rinsing.