When I was 100% trad for the downstairs I used any cleaning stuff that contained sodium hydroxide, caustic soda, i.e. Strongarm, G101, etc, and a 10ltr spray bottle to wash it off. I sprayed the stuff on with a hand sprayer, used an Unger wfp flocked brush to scrub the frames and rinsed it off with just water using the 10ltr pump sprayer before trading the windows.
For upstairs, I just used any hard surface cleaner and those pound shop green scouring sponges and scrims to wipe it off. It didn't as good a job but when up a ladder you can't spend all day getting the frames spotless and white when from the ground floor, you cannot see the difference.
To be honest, I tried Ecover years ago and found it............... sorry, but there's much better out there that does a much much better and quicker job.