I've use the dunk and soak method, when I've had powder mildew, and it works. Its a lot of work, and prolongs the trimming process big time. But if your like me, and refuse to lose a crop, then you got to do what you got to do.
I cut down a plant, dunk it in water ph 12.0, hang it in front of a wall fan. Let dry for 45 minutes. I do that twice to each plant, then trim. Set up a rotation, so as you're trimming one plant another is hanging for the first time, and one is hanging for the second time. Most of the visible mildew will be gone, still have to trim into the more effected leaves. The key is to change the ph level of the outer leaf/stem/bud, so that it doesn't grow back out. Be careful when soaking, DO NOT thrash it around in the water, don't want to wash off any more res'n then you have to. Also, when I say trim, I mean wet trim to the nug. I leave no leaves and no stems, just the bud, that means you don't hang dry then trim. Yeah I know all the reasons why not to do it this way, normally, but we're trying to save a crop and get something out of it. This does two things. 1. Powder Mildew has less to grow back on, since you got rid of as much of the infected areas as possible. 2. When you cut the leaves and stems off and just have the nugs it drys faster, and takes the moister from the mildew faster.
After you're done triming and drying, sterilize/destroy EVERYTHING!!! And I mean everything. Destroy or trash things that you can't clean. Bleach and Water is your friend. If your grow room is carpeted (nightmare, but I think I saw you say you're in an apartment), squirt highly ph'd water on the carpet. Never go from working with infected plants to non-infected plants. Do not put infected planets in the same room as non-infected plants, you will care spores over. Powder mildew is a fungus and spreads from spores by touch, wind or any means it can. Lower your humidity and up air flow. DO NOT just clean once. I clean 3 times, allow the room to sit and dry each time. Use fans to speed it up.
Good luck man.
