If it's green, isn't it more likely algae?

Over the last several years, my approach to growing has taken a fairly significant "shift", and I find i have far fewer issues with algae, molds, and rots:
  1. I have drastically reduced the amount of fertilizer I apply. At one time, my fertilizer concentration was 100-125 ppm N, and now it's roughly 20% of that.
  2. changed to a fertilizer formula that is very low in P & K (K-Lite, 12-1-1)
  3. Stopped using disinfectants as a preventive measure, and try to avoid them altogether, unless I have a severe outbreak.

The reduction in overall fertilizer use, coupled with the low P, has essentially eliminated algae growth, even in S/H pots.

By eliminating the use of disinfectants, which kill beneficial microorganisms as well as pathogens, and by reinforcing those beneficials through the use of a plant probiotic (which also helps the algae reduction) I see overall healthier growth, with far fewer problems.