Most efficient cleaner for my setup?

[jeffnc226]

I do small time pressure washing - not my full time business. I'm looking to do concrete (driveway, sidewalk, etc) as efficiently as possible. My unit is Milwaukee 4555-22 3750 PSI 4 GPM Honda GX390 AR RKV pump.

I've tried this unit from Northern Tool, but it's far too streaky or swirly, so to speak. To not get any swirl marks, I have to go so slowly that it's worse than standard wand.
http://www.northerntool.com/shop/tools/product_200041024_200041024

I've also tried this unit, but the pressure is too low with 3 tips - it doesn't get as clean as with a single wand. I'm currently using this with just 2 tips, and blocking the third. This only doubles my efficiency, but it is much more comfortable than using the wand.
http://www.northerntool.com/shop/tools/product_200517714_200517714

Without going to a much larger rig, is there anything else I can do here? I'm not really a fan of chemicals on concrete, because sheer pressure gets off the grime much better than anything else I've tried, but I'm open to suggestion. Possibly the 3 tip roller with oxalic acid after to brighten or something like that might help?

I've got a big job coming up so I'll be practicing anything new in my driveway.

 

[Pat Norman]

Well most people here use the rotary surface cleaners. 4gpm is a little small for surface cleaners but many use the 18" whisper wash classic. That Northstar machine is probably junk. Also most here use chemicals too. Helps eliminate stripes and cleans better and brightens mainly it speeds up the job. For driveways and walks with mildew most use a sodium hypochlorite (bleach) and soap mix before and sometimes afterwards and leave. For commercial use caustic and neutralize where grease and oil are present. Search and study.