White residue on exhaust fan

[JimG]

Not needing a carbon filter any longer, I went to a straight exhaust. Like the cloth wrap on the filter, a white residue formed on the mesh filter on the intake side of the fan as well as the the inside of the fan. It's kind of sticky and I used to think this was coming from the plants but now I am not sure. This is what it looks like magnified.

[quirk]

Don't know if this is the cause for your situation, but my white residue problem was due to using tap water in my humidifier. Wiped down everything, switched to distilled h2o and no more white residue. Good luck.

[JimG]

I think you hit the nail! I recall a humidifier that had a special filter to prevent that. That is a very expensive switch with distilled water at $1.25 a gallon. Have not noticed any microscopic evidence on buds in 25 grows. Thanks for the reply and reminding me of the filtered humidifier.

[JimG]

Going to try softening the water at the tap.

[Bluey]

You could try using the water from a dehumidifier. It is demineralised but it is ionised and does corrode some things badly