I have been using wfp for a while now without any major problem, but the last few days dirty water marks are running down across the glass after I have walked away. My water tds at brush is 001 Firstly I blamed the new cill brush and new pole. I thought that because it was different weights and shape, my usual method of working was now not working for me. After three days of this I have returned to my old pole and brush. Same method as before, good wash and rinse. But these marks still appear. I'm a bit confused and frustrated as I pride myself on doing a good job. The windows seem to be sheeting into triangluar shapes and on drying you can make out these triangular marks. Any one had similar?