Can anyone tell me what this is?

I got some white stuff that started showing up on my clones. They are in
18 hours a day of light with humidity between 40 and 60% in ventilated grow tent.

Can anyone tell me what this is? The first one is from a distance, there are little patches like this on 20% of my plants. The second and third are close-ups to show the formation; it almost looks crystalline.

seems to be mold, but i may be wrong. you should take that off right away so it wont spread

I sprayed with serenade as a preventative. If its not cleared up by tomorrow morning, I plan on dropping the humidity and hand wiping all the leaves.

As a follow up, the serenade did have an impact. However, I decided to spray and wipe the rest with foliar sm90. Cleared it up on spray; I will reapply every three days for a while (three days is the lifecycle of many molds / mildews).