Found these crystals in basement vent. What is their purpose?
Take your best guess I have no clue:neutral:
It might be a product like Damprid or a deodorizer.
Some people think it keeps the animals away.
Thanks for the info…I was just curious if others had an idea. I found biogrowth in the area. Maybe they were trying to get the odor out or something.
Sure a lot of rust on that vent cover. I’m guessing a moisture problem and I think you might have it right that this may be some kind of odor killer to mask a mold problem. …they might call it “Crystal Vent”
Looks like ice melt crystals they turn blue when they get wet, or could be some kind of mouse poison.
Home Inspector LLC
The ice crystals might make sence as I saw some blue staining on the concrete floor. Do they use this to try and keep mice away? Had dead mice in the area as well.
It looks like copper sulphate, aka blue stone, I use it to kill roots in the sewer, it is used as an algaecide to kill pond weeds too, it kills any kind of plant and fungi (mold). It has also rusted the coffee can I store it in. I have never heard of it being used in HVAC vents though. Oh and wikipedia says “it can be irritating to the eyes and skin” and is very toxic to the environment (cause it kills plants)