i used to use gg4, since going wfp , i now use gg3 with ro water.
i find you need less gg3 than gg4 if using ro water,
agree that it does a superior job,
when i first started to use it i noticed a slght film was being left,
i now know this was the glass gleam, stipping of layers of fairy that i had used for years,
after 2- 3 cleans every thing was stripped of glass, it is then you see how good it is.
this makes it ideal for use in the mths prior to going wfp,
as when i did , i had no problems,
i also use it now for first cleans, in a bucket with an applicator, then wfp after results are amazing.
it is one of those products . you have to use for a while to fully see the benefits.
daz