I HAVE A LANDA WATER JET THAT I AM HAVING PROBLEMS WITH. WHEN I CLEAN CONCRETE, IT IS LEAVING STREAKS. THE PATTERN I USE WHEN CLEANING IS WALKING THE LENGTH OF THE DRIVE WAY THEN TURNING AROUND AND GOING ALL THE WAY BACK. OVER AND OVER. HOWEVER, WHEN I AM DONE YOU CAN SEE A 5 - 6 INCH WIDE STREAK, THEN A 3-4 INCH WIDE AREA THAT IS CLEANER, THEN A 5 - 6 INCH AREA THATS A STREAK (DARKER), THEN ANOTHER 3-4 INCH WIDE AREA THATS CLEANER ETC. ETC.

I HAD THE FILTER ATTACHED TO THE WATERJET CLEANED OUT, AND THE NOZZLES ARE DEFINATELY LINED UP CORRECTLY, AND HAVE HAD THEM ADJUSTED MANY DIFFERENT WAYS. 15 DEGREES, 20 DEGREES, LINED UP BY THE LANDA TOOL THAT CAME WITH THE MACHINE ETC. THERE IS NO PLAY IN THE SWIVEL DEVICE! THE NOZZLES WERE PUT ON ABOUT 4-5 JOBS AGO. THEY ARE 15 DEGREE / 2.0 SIZE NOZZLES. I USE A 3500 / 4 GPM LANDA MACHINE. CAN AYONE PLEASE TELL ME WHAT ELSE THE PROBLEM COULD BE. I HAVE TRIED THE LANDA WATER JET WITH A 4000 PSI RENTAL MACHINE THATS 4 GPM AND IT DID THE SAME THING.
THANKS.

BILL

i think your cleaner may not be very effective,on very dirty concrete we use 50/50 hydrochloric acid aplied at 2 to 1,on areas that are black with mildew cleaning once with surface cleaner and touch up with wand is common.