I used hypo for the first time today and was very happy with the results. I bought cheap Morrisons bleach for 28p for 2 litres, it said it was less than 5% so that could mean anything so I diluted it 50:50 with water just to be sure. I sprayed it on the GFS I could reach and used UBIK on the rest, after half an hour I just rinsed it off. Much to my horror some of the gutter and part of a French door had gone orange! I had read about this but it was still a bit of a shock so what did I do I sprayed more bleach all over the GFS, left it another half hour and washed down again. Just for luck I decided to use UBIK as well so sprayed that on, left for five minutes and scrubbed off with my wfp by which time all the orange had gone and the GFS were very clean. I was just experimenting so didn't mind spending a bit of extra time on this job. Next time I am going to try UBIK first then hypo to see how that comes out.