The concentrated flash in a squeezy bottle is an excellent all round cleaner.
I have 5 con roofs to clean over the next couple of weeks, a couple are really dirty, so been playing round with different chemicals.
Flash in a backpack with pure gets excellent results, removes grime easily, even easier then virasol ubik etc.
Tried some flash in a bottle with pure and a dash of descaler, sprayed on some dull stained sills today, came up really nice.
Also a dollop in trad bucket with my normal chemical ( window cleaning warehouse pure shine) and trad results are excellent, dirt and grease melts away.
Most of these chemicals, ubik, virasol, tfr etc are not all their cracked up to be.
Good old fashioned flash and cif cream are the 2 best cleaners for f/s/g and con roofs and are cheaper and more accessible.
Flash does the cleaning, cif removes almost all staining.