LOL I use ZEP all the time but not the purple, I use the calcium and lime remover. On light dust there is no need for scrubbing, obviously heavier neglect does but works like a charm, strong smell when spraying though. And no damage but needs to be rinsed very well and wiped to make sure no residue. I also cut it 50/50 with water so a bottle goes a long way!
I buy the big blue bottle in the cleaning section at Home Depot for around $19?