SERENADE UPDATE:
it’s honestly really hard to tell if the rust is progressing as it’s on every leaf except for the new growth, and it’s hard to keep track of the new growth. i started taking pics but then also realized if i don’t shoot from the exact same angle and distance, it’s still hard to compare. so i’m going to get better at doing that.
I got the Serenade yesterday, and after my hydrogen peroxide learning experience, did one test bud on each plant. it turned my lovely white pistils to shriveled amber. i don’t think i’ll be using it unless i feel like i can paint each leaf with a q-tip but that could take a week. going to research baking soda next but i think i read somewhere it did the same to other pistils.
I also got a whole room dehumidifier and moved the intake ducts from the outside hallway back into the bedroom so i can create a closed system. the room is still warm, so will keep an eye on the temp. after two hours we’re at 78 degrees and… each hygrometer has a different reading. the cheap ones are at 47% and then my bluetooth probe says 53%. 
Thelma’s pistils are all thick and shooting straight up. made me sad to see this this morning.
I flushed them both two days ago and last night did a full 100% feed. Will do again tonight to cover my Calmag bases.