The lower leaves on the phalaenopsis turn yellow with stains quickly

[Roberta]

First, welcome!

The yellow leaves are probably just old. Let it drop naturally. The crack in the good leaf is just mechanical damage. The pot looks to me like it has poor drainage - you should repot into something a pot that will drain better - personally I like bark, but loosely-packed sphagnum will work too. The goal is "humid air" rather than "wet" in the root zone.

I don't see any purpose in boiling water... best watering practice is to put it under the faucet and let water run through the pot (which flushes "junk" and also pulls air into the root zone) Note that after you repot, you will need to water more often, since the new medium will dry faster. Which is exactly the goal. (Also winter heating reduces the humidity, again leading to faster drying) To determine watering frequency, consider weighing the pot on a kitchen scale or postal scale right after watering, Weigh the next day, etc. When the rate of weight loss decreases (less water to evaporate) it is time to water again. Also with winter, be aware of cold drafts... you probably do not want to have the plant too close to a window.

If you repot into a well-drained pot, I don't think that any treatment is necessary. Just create a healthy environment in the pot a and the plant will take care of the rest.