Suggestions to help prevent fungal nonsense?

[uwodahikamama]

I am pretty sure I’m dealing with a fungus. I’ve also seen fungus gnats a few times I believe. I saw some mold in a pot of a rescue Cattleya that I repotted (and had used peroxide on). I noticed in one of my rooms where I keep my Phals that a few of them had yellow round pale dots. Not good.
I look at them often so I think it’s recent. But given that it’s on several of them I want to move quickly.
So I ordered Physan 20. It had great reviews.
Does anyone use it regularly as a preventative? What sort of dosage/schedule do you use for that?
My biggest question is how to prevent this from happening again. My temps don’t go higher than around 78 during the day and go down to around 64-65 at night. I have my humidity levels set to 60% though sometimes this summer it can get into the upper 60% depending on the weather outside.
I have a small fan that blows constantly every day, and an air conditioner that pumps at night.
Is my humidity too high? Should I keep my temps a little lower? Do I need a bigger fan? I don’t always have the fan on high, sometimes it was on low on cooler days, maybe even a day or 2 it was off. Only because I thought it might keep the temps from getting too cool during the day and because I read that you don’t need much for it to circulate the air.
I can keep it on high every day though if that’s an issue.
I really thought my care was on point!