Fan for phals

[Emerald27]

Hey everyone.

I have 4 phals, and was using the skewer method to determine when they were needing watering. The skewers started to develop little bits of fuzziness, what looked like mold.

In a different thread I asked about this problem, and it was suggested that my plants weren't getting enough air circulation during the winter months. I bought a mini desk fan and a timer, but I'm unsure of how frequently I should set the timer to turn on the fan, and how long to keep it on for each time.

Any suggestions would be appreciated!