White mold on terracotta pot exterior

[Salixx]

A little while back, I experimented with a Masd. chaparensis in s/h and a regular clay pot to increase evaporative cooling on a plant I couldn't quite give the temps that it wanted.

From the plant's perspective, it has been a success. Shortly after the repot, I had an explosion of new growth. I have since (and plan to continue) to use this method for my other cool and cool-pref growing pleuros. I currently have three different masdies in clay pots and want to do more.

The only real "problem" I have run into is the growth of white fungus/mold on the exterior of the clay pots that looks like hard water deposits. I don't care all that much about it, but it is quite slimy and gross to handle at watering time. I have been wiping it off with a cotton ball soaked in 95% isopropyl alcohol. This has curbed the growth, but not eliminated it and I still have to do it every one to two weeks.

Are there any more 'permanent' solutions to this? I am looking to cut time spent on things that aren't necessary while not causing harm to my plants and potential beneficial bacteria and fungus that may be in their root system.

Thanks for any help!