First cleaning.
I tried walking different speeds, pre treat and no pre treat. Still have the striping. I have a 5.5 @ 2500 and a 20 in GP hammerhead. A second pass takes care of it. Any suggestions? I have not swapped tips yet. Will that help?
Stronger post treat
Your solution.
This is why everyone should have a way to spray 50/50 instead of just relaying on DS
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I would 50/50 with a pump sprayer.
Also, Are use you are using the correct tips on your GP hammerhead?
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I have 25020 in it. My next project is a 12v system, but I have to get this investment making some money first. I am gonna do bucket tests tonight to see what my pull rate is so I can get the strongest mix possible.
Just use a pump up for now and post treat with a hotter mix.
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2500 psi 
Hotter chems will fix it, but that’s not the way to go.
A 5.5 and a 20 inch requires you to go at snails pace unless you pre treat and post treat with a strong mix.
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Because it’s not cleaning it first pass.
The bare minimum pressure to make that SC just work is 2000psi.
In all the years I’ve been cleaning concrete, 3000psi is the sweet spot.
There are a few you’d go less on, but yeah - 3000psi.
You can also use an xjet to post treat.
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I’m at 2,800psi with a Classic running 150 feet hose… No stripes here…
I have stripes 75% of the time. I’m at 2,900psi at the surface cleaner. I think it varies from substrate. Post treat works.
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To OP, When applying chems on a sloped surface(driveway) always start at the bottom of the slope so you don’t wash off your chems and dilute them even more as you wash… Bottom to top
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No doubt. I can’t imagine being limited to DS. I ALWAYS use my 12v system to post-treat and watch all those stripes just disappear. X-Jet will perform that function nicely too.
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You have a 20” whisper?
@Harold Yep, I can definitely see that happening below 3000psi. What size is your SC?
The bigger they are, combined with the lower pressure - the worse they are I find. The larger diameter = slower spinning = slower walking. So people tend to go faster than they should and this causes the problem. Not cleaning first pass.
@MrSparkleVA Using a hot 12v system to bleach out the lines isn’t (in my opinion) doing a proper job.
Post treat isn’t really to fix, it’s to make a nice even overall finish with an added residual benefit.
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20” 8gpm
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Not sure where people stand on “cleaning power” formulas, but I think they make sense.
So the OP has 5.5 x 2500 = 13,750.
A standard 4@4 is 16,000 16% more powerful (on paper, probably 14,000 due to only 3500 actual)
Pressure is still important, not just flow, flow, flow.
Yours is 23,200 68% more powerful than OP and 45% more than the 4@4.
Annnyway - there’s still a certain amount of pressure required to “lift” dirt and not damage at the same time.
Pre treat to start the cleaning process, SC@3000 and post treat to make a nice finish and residual mould killer.
About that post treating, does it have to be rinsed as well or does it just sit there and dry out in the sun?
