I've had problems with PM recently since moving close to the ocean. or maybe there's mold in the walls, I dunno. But I've never really had to even think about it before now. I have good airflow, and my temps are around 75 with humidity around 50. I got rid of all my blumats, and I was spraying things down with a little neem oil and dish soap for a while, and that would manage things for a week or two. I spray clones with just a little dish soap and that works well. But it was tough to get a plant through flower without it eventually becoming powdery. It seemed like the PM would appear more rapidly if I let a plant dry out too much. like if it wilted a bit and then rehydrated, within a day or two PM was trying to take over.
I purchased a $100 hepa air filter on amazon just to give that a try. I have not seen PM since. mold spores are big, and are easily filtered from the air. I have two tents inside a small bedroom, and just leave the hepa filter located in the middle of the room, and running all the time. Even with my exhaust constantly sucking air out through the tents, it's been working great. I highly recommend giving it a shot.
don't spray your plants with baking soda