General Pump Surface Cleaner Problems

Hi everyone! This is my first post although I’ve been researching on this forum for the past 5 months. A lot of great info so thank you to all who post on here. I just purchased a general pump hammerhead 20in surface cleaner. On the very first job I got lots of lines on the driveway. Not lines from going to fast but straight lines as if its cleaning more on the sides than in the middle. I’ve read a lot on here about this issue but was hoping I could give some specifics and somebody point me in the right direction to getting rid of them.

I’m running a 3500 psi 4gpm machine. The tips on the surface cleaner are 2502s. When I pressure washed the driveway I both post treated and pre treated the driveway with a house wash mix. I used an x jet to put the chemicals down with straight 12.5 sh and some ecofresh wash. I used beige proportioner so I believe around 1.2% bleach was sitting on the actual concrete. Like I said its a brand new surface cleaner.

Do I need to use different tips. Maybe a 2503? What else is weird is that there was some concrete in back that was clearly newer and when I went over that it left zero lines and the sidewalk had zero lines as well so its like some concrete it was streaking and other concrete it wasn’t. This really isn’t acceptable work in my opinion so I’m hoping somebody can give me some direction. Sorry for the long post. Just trying to give as much information as possible. Thanks for you help!

Ditch the house wash on cement. Waste of product and money.Apply bleach only after you’ve run the surface cleaner over it and rinsed the entire project.Then apply your 12.5 % .(not before the project–another waste of money and supplies). Are your nozzles on the surface cleaner running the same direction as the spray bars ? they must be inline --making and I formation , not a T formation. Are you going the correct speed for the cement you’re cleaning ? Are you cleaning in a hurry ? That photo looks like the cement is still wet. How did it dry out ? * Also I see your machine is un-even -while you’re running.I never like to run my machine like this. I carry boards to make it even if i’m strapped for level ground on a job site.

Looks like a clogged tip. Always soak concrete with housewash before surface cleaning. Never wash dry concrete. rinse and if necessary put down a light coat of housewash and leave.


Thanks for the quick responses. The tips are not clogged and they are lined up making an I formation. I was definitely not in a hurry. Went vary slowly. I’ve used surface cleaners in the past going much faster with no stripes. When it dried out it looks much much better. Barely even noticeable but is it acceptable for there to be stripes when wet? And great tip to not leave the machine at an angle. Never even thought of that. Also should i pre treat or not haha. You both have different view on it.

Change your tips, right now your putting out 3500 psi.
Residential concrete has a max psi of about 2500psi.
Was the wash water milky white, or a lot of sand in it?

The water wasn’t milky or sandy. Everything seemed fine. It actually looks really good when its dry. I just don’t like that it has lines when its wet. But I do agree the tips need to be changed. Thanks for your advice!

Hi, give me a call and I’ll help you solve your problem.

The lines could be caused by excessive overlapping. How much are you overlapping?


I do up and down then a left to right…
A circle motion does better as well
Any light color drive way gives me lines does not clean up very good,

Buy a Mosmatic --you won’t have problems.

Hello everybody, I’m having the same problem as the one described by Solarskikm, I’m running a 4gpm/4000psi and an 18 inch gp hammerhead surface cleaner. I noticed a lot of sand in the water while pressure washing a driveway and the same lines appear on the concrete. What tip should I be using? Any ideas?
Thank you all in advance for any information that can lead me to fix the problem.

What tips do you have in it currently?
If you are using the stock tips than all that sand is concrete be blasted away from you stripping the cream off the top.
The max pressure residential concrete can handle is about 2500psi.

Most likely the driveway was ruined before you got there. Did you notice a shitty surface before you started cleaning it ?
These are things new guys need to look for. Most homeowners will pressure wash with a gun and their cheap ol pressure washer around their garage and in front of it.They’ll leave the remainder alone because they’re lazy and it’s too much work to do the whole driveway with a cheapo and a gun. There you will see the rough looking cement… I see this 50% of the time. Damage done---- don’t worry about it. The other thing I see sometimes is some idiot who has put salt on his driveway during a snow storm or an ice storm… This will also ruin the cement or the “cream” of the cement. Damage done---- don’t worry about it. We’re not miracle workers.Once you put lines in the powdery ,rough cement, they aren’t coming back out. No amount of bleach will help either. Best advice in the world…
" WALK AWAY --before you start !

Hi Solar - the stripes are cleaner than the rest. A surface cleaner will clean better at the sides than the middle as there is more overlap, therefore more cleaning. You need a system where the least cleaning ability (the centre) is enough.

I would apply chemicals first - chlorine bleach at about 3%, and if it’s very dirty overlap the s/cleaner by 50%. After rinsing you may need to spot clean some stripes or retreat heavy mould/moss.

As a rough guide your s/cleaner should be 4" wide per gallon, so 16" wide.
According to my nozzle chart you are using 4000psi (2 x #2 = #4 @ 4gpm = 4000psi). If you change the tips to #2.5 you will be using 2500psi (2 x #25 = #5 @ 4gpm = 2500psi).

Nozzles & spinner bars are cheap, so try 2 x #25 with a 16" bar and see how you go.
The biggest change I would suggest is increasing the amount of chlorine bleach.

John from All Exterior Cleaning

Ok, so I too have just bought an 18” GP hammerhead Gz. I have a 4000 @ 4gpm belt drive Cat pump (thanks for all the advice) . I hooked it up and is seems fine for the 1st 30 seconds then slows down like to a crawl. I used my neighbors 20in BE on his pump, homedepot bought - Dewalt 4@4 and how did the same thing. My concern is I’m running a 100 ft regular garden hose to the intake, When he did his sidewalk it looks great! Mine not so much, and I’m doing other neighbors sidewalks for training purposes. Is it my hose and do I need it closer to the inlet for water supply.

Most of those guys above aren’t even around here anymore. Donte pops in on occasion though.

Your 100’ of supply hose likely isn’t going to make a difference. What could is if your spigot isn’t putting out enough water. Take 5 gallon bucket, start filling, and start timing. If you get less than 4 gpm that spigot doesn’t have enough water to run that machine. Most put out more than 4 gpm but it’s worth checking. That’s why a buffer tank is a really good idea. You’ll get on some houses that might only put out 5 gpm and, you think you’re good to wash, and then the homeowner jumps in the shower or washes a load of laundry. Your pump will then be starved for water.

I’m not positive but 18" might be pushing it for a 4 gpm. What size nozzles are you using? Are they installed correctly? If the orifices aren’t in line with the bar, even just a little, it’s not going to run right. I would also take the nozzles out and flush the lines just to make sure nothing is clogged.

Have you set your unloader?

Hi, and thank for the reply and apologies for slow response on my part. I have gone a bucket test and I’m getting full 5 gl in 38 seconds. So the supply tot he hose is not the issue, I have heard even with a good supply the hose can collapse and restrict flow. I saw a video to day about bar height, When they come from the factory is that a recommended setting or they just throw the head in? This is the factory set bar height.

still learning and I see you on a lot of the other post and am great full for rue knowledge you share.

The tips are 25020 and 1 was just off a hair. Took it out retaped and reset to be in line with the bar. The unit wants to tilt forward as in the Bach isn’t touching the ground, the next test I’m going to pull some of the head hose back so not to have such a big forward bow in the line. I’m just breaking into the business, but want to be better than this guy!

this is my sidewalk and the neighbors after I did a surface clean with a 15 EZ clean, no post treat. Still haven’t gotten up the courage to spay a Chems yay since I do live next door and would never hear the end of it. I told him my house was a model hose and his concrete was poured later. I’ve never bleached my sidewalk in 9 years, but I can see someone has used to much pressure and wipe off the cream from theirs as I see exposed aggregate.