i just thought i'd say i've been using mdr and crystal clear 550 with great results. expensive stuff compared to harpic but then i always explain when viewing property if the glass will require the product and up the price by £5 to cover costs
i've found that crystal clear gives better results but i find i have to use harpic quickly first to remove the bulk of the limescale. mdr is great on it's own for bad limescale but it doesn't remove as much as crystal clear, though it's still very very good.
only thing that takes time now is applying and scrubbing the glass which i'd like to try and see if there is a way i can reduce this with a machine. anyone know of a small handheld rotating machine that'll work good for the shower doors? needs to be small enough to work for those folding shower doors that have thin panels.
also how do people deal with removing bad limescale from the corners of the folding/sliding shower doors? i had one wednesday that took me ages as i couldn't get to the limescale as easily as i'd had liked so had to use a knife to scrap each tiny bit at a time, but there was approx 8 corners to each side so i was there far too long. can't think of a better way to deal with it.
example of what i mean though the one wednesday was inside a slide so it was harder to get to
https://www.lowcostbathrooms.com/showers-enclosures-66/shower-screens-228614422/image-shower-screens-228614426/image-coral-5-fold-10798-7716_medium.jpg