Black dust in and around pots?

[OrchidNut555]

Hi everyone

I grow my orchids inside a milsbo cabinet with t8 barrina led grow lights currently on for 12 hours everyday. temperatures are aeound 21-23 degrees c. humidity i have yet to measure as i don't have a devuce for that yet.

All my orchids (mostly mini cattleyas and latouria dendrobiums) are doing perfectly fine: new growths, new roots, everything as good as can be. I do have some algae formation though.


I give all of this information because inm extremely puzzled by something: there is a sort of black dust collecting inside the trays/ pots i keep my potted plants in and also around them. it genuinely looks like black dust. The milsbo cabinet is black, but i see no colour flaking off. the dust doesn't move , i see no harm on my plants. under a magnifying glass i don't see much. it either looks like dirt or seems to have a spindlty leg or two but since NONE of the specs move at ALL i am unsure if this is some kind of weird mite or genuine dirt and i have no clue where it came from.

again, i see NO infestations of ANY type of pest or bug or anything at all on any of my plants.

Woulf any of you know what this is? i attachef a photo to show whqt the black specs look like

Thank you in advance!