Powdery mildew very close to harvest. Day 45. First grow.

Hey guys, wondering if I could get a little help here... 99% sure I have a knarley case of good ol' powdery mildew.
I'd like to say thanks ahead of time for any help, even if its directing me to a thread that addresses this same issue. The reason im posting is because I have read quite a few posts, not just here at rollitup, and ive heard a lot of solutions, tried a lot of them, and my plants are STILL infected.
Ive tried raising the temps to 100° for an hour...didn't work. Ive mixed milk with water (ratio of 1:4) and sprayed them every other day for 8 days...didnt work. And recently ive been spraying them with activonate (?) mixed with PH'd water of 9.0 every other day and still, the pm wont go away. Now that its so close to harvest I was wondering if there is anything I can do. I first found the pm (in the tinyest amount on ONE young leaf about 3 weeks ago) and i have been taking action ever since. First off I'll list the stats.
--6 plants of 707 headband. (Indica dominant) Right around 3ft tall. Day 45 in the pictures. Day 47 today.
--Growroom is a 10'x4'x8' in the garage. (Plywood room, expecting to grow a lot more more plants after this first grow.)
--1000w hps with an 8 inch inline fan and carbon filter (something like 350 cfm) passive intake hole in the wall.
--soil grow, fox farms ocean forest. 5 gal grow bags.
--Water 2-3 times a week. (PH'd of course) With fox farms food. (Grow big, big bloom, tiger bloom) no foliar feeding at all.
-- big floor fan that doesn't oscillate facing one of the walls (way too powerful to face the plants)
-- temps between 65 and 80 F.
I'm planning on harvesting these girls in the next week or so.
Please help me!

Sorry guys, I guess posting pics on a forum from my phone doesn't work. Ill be able to add them 6 hours from now. Thanks again.

Sorry to hear about your powdery mildew problem. I have struggled with these same issues myself more than once. I am surprised milk did not work for you as I have had a lot of success using it. I have also heard that once you have powdery it is almost impossible to completely get rid of. I just thought I would refer you to a Jorge Cervantes video I recently saw on youtube. He mixed about a cup of hydrogen peroxide into 5 gallons of water and dunked the limbs of his finished plant into it. You can watch the mildew dissolve into little oil slicks in the water. He then rinsed the limbs with some water and hung them in front of a fan to dry. Really amazing stuff.

pm is a bitch lol sorry to laugh but i can as i have delt with it myself, I see a few thing you are doing wrong, first off you should have quarantined the the sick the first time you saw it, treated it, the treat the healthy with ed rosenthal's zero tolerence, you made it worse doing all the spraying you did, you created a breeding whore house when you jumped the temp, you can how ever do a very short sulfur burn and your pm will be history then after harvest do a heavy sulfur burn in the room to prevent it from coming back ever, keep humidity below 50% at all times especially lights off

Thanks for the replies.

Wheelt01- Ill have to check out that video. Sounds interesting.

Drifter- Thanks for the advice. Now, this is gonna sound really newbie but, can you link me to something on sulfur burn? I have a hydroshop around here but he doesn't stock much stuff but he can order just about anything but it usually takes a week for stuff to come in. Also I've heard that spiking the temps in the room to 100° will kill pm? Is this wrong? I try very hard to keep the humidity very low (I.e. huge fans and air circulation) but the fog in my area (SF bay area) is pretty crazy this Nov/Dec. Again, thanks for the reply. Pm is indeed a bitch.

I have used Excel LG with excellent results. Ive only encountered PM twice and the Excel LG destroyed it withing a few days. I am not quite sure about using it close to harvest however.

im sure someone will cry like a ninny but you can burn sulfur with a hot plate and a old pot lines with aluminum foil and 1 tsb of sulfur pellets turn on low watch it turn it off as soon as you see vapor and it starts to melt get out of the room and leave all ventilation off till a hr before light on, kills pm in one shot 99.99% of the time provided its not a pm jungle, fans will not help humidity, only push it around get yourself a 40-60 pint dehumidifier other wise you will continue to combart the humidity and posibily pm, i live in washington i know all to well about humidity issues, try to keep your night time temp drop to 10-15* no more as the cooler it gets it allows the moisture to reach dew point faster