I'm using a Vicks V420 for the first time and am finding it a lot different from my previous wick-based humidifier. The surface of my substrate is beginning to yellow, and areas of condensation on the greenhouse walls are also yellowing. The substrate in general looks unhealthy and perhaps overlayed. It's been seven days and there are no signs of primordia or pins. A monotub of the same strain that I began fruiting at the same time is already pinning.
First of all, what could be causing the mycelium to turn yellow? What property of my water would be causing that and is it damaging to the mycelium?
Second of all, what causes overlay, exactly? The edge of my monotub that receives airflow from a circulating fan in the room also shows the same kind of growth so I feel it may have something to do with drying out or something. But I've also maintained 90+% humidity so I don't know. I decided to go uncased this time around for simplicity's sake but it seems to be more sensitive.
Here are some photos:
Tub 1

Tub 2

Tub 3 looks like tub 2.
Help!