5000 sq/ft driveway

Biggest job in three years, took three hours…kinda shocked to be honest.

I post treated with 3-4%, let sit for a while but this still wouldn’t disappear like it usually does.

I tried hitting it again and rinsing 20 minutes later but nada. Finally just said the heck with it and housewashed post treat and called it a day.

I’m always up for suggestions, aside from heat, what more could I have done?

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For me, usually after a post treat, and once it starts to dry it whitens up. I did some work for a handyman that probably wanted to study what i was doing and how(goodluck right?). He was so taken by his white the drive came out that he had his son go over and take a wire brush to it just to check. Pre and post treat usually take care of anything thats been already washed with power.


I’m sure it disappeared once it dried

Jesse do you find pretreating helps enough to make a difference with this stuff? I may start hitting it with housewash mix first.

I go back in a few days to do the windows so we’ll see how it turned out. The homeowner gave me a big thumbs up message so that’s encouraging.

I always pretreat now, sometimes twice because it’s so thickly coated with black film. It cuts down on the passes for sure when the organics are bad.

Congrats, that’s a nice drive. Post the same pic when you go back after it dries. Think you’ll be good. Looks like you made 2 passes down the sides, as you should. But you can see it’s a little darker on your horizontals, like maybe you only made 1 pass on each. You can do that if not real dirty, but you need to walk a little slower or make 2 quicker passes on them. Normally you won’t see quite as much discrepancy. But as I said, think you’ll be good. I’ll try to post one I did today later on 20 yr old concrete that had only been cleaned once, that I have some shots about the same time frame as yours, maybe about 5 minutes more drying time.


i always pre treat with x jet so when i run over with my surface cleaner i know exactly how fast/slow i need to go. in your case, i believe you went to fast. if you only post treat there may be a few spots left behind. but if i pre treat, once i’m done surface cleaning the job is done. after rinsing of course

I’d say my walking speed was a ‘slow shuffle’ on this one.

@Racer I did do a double pass on the sides, good eye. I’ll have to try the double on the horizontals as well.

Oh one more thing, those black lichens! Scientists need to figure out how to make body armor out of them because direct blasts of 1700psi nozzle didn’t phase them. 4% and dwell lightened it up about the same shade as the driveway but wow.

Turbo nozzle on the lichens.

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@dcbrock Wondering what kind of machine/gpm you were running. I just did a pool deck and took way way longer than 3 hours. There were spots I was making 3 slow passes on with a 4gpm machine. Mid way I learned that pretreating speeds the cleaning process along much better for me.


I have an 8/3000 machine and the SC has four 2500psi nozzles. I may upgrade to a 24" SC soon.

IMO, pressure washing without pretreating is like showering without soap. First, it helps kill and loosed up organic buildup. Then, it’s like a hurricane inside that surface cleaner, so a bit a bleach and surfactant inside there is going to help clean more than plain water. I like seeing a little bit of suds when I’m cleaning.


Are you using housewash mix or 3%?

I’ve been fighting the lines in my concrete Cleaning this whole season. I have a 8gpm 2900psi washer with a 19 inch 4 tip surface cleaner. I must be doing something wrong because I’ll pre treat with 6% then post treat with 6%. They all have lines until post treatment. I will say it makes a world of difference to pre treat.

Same exact setup as yours. I’ll try the pretreat next time. Unfortunately I just have a portable 12v and 5 gallon jugs so filling them from my main tank is a chore to say the least. Some day when I grow up I’ll get a decent 12v system with proportioner.

Get you some cheap crappy pentair valves and it won’t be a chore. Batch mixing anything is long gone brock. those that love it haven’t realised you can do it without the Manual labour, tank markings and record keeping of chemical strength.


I use a strong HW mix, about 1.2%. I’ll go 2.5% if it’s really bad. Any spots that look like they could be oil or something non-organic I hit with degreaser as well. I treat, then get my pressure washer setup while it’s dwelling.

Nice @dcbrock. I did a 4000 sq/ft drive recently. I always just nuke the drives with a 4-6% pre treat mix and house wash mix for a post treatment. I don’t want to waste time treating again because the lichen on the concrete didn’t want to budge with a 3% mix.

Turned out wonderful. Here’s the before and a mid job pic. The complete after pic I believe is on my iPad but I’m too tired to go out to the truck at the moment, I’ll edit the post later if I find it

I am seriously looking into it. Maybe Southside can hook me up.

@DJPWS Thanks Dustin!

Just started using my proportioner. You won’t regret it., thought it does take some getting used too. Now I just need the downstream remote controller.