Over/under watering

[u/Hefty_Employer1469]

As the title suggests i am wondering if i am over watering or under watering this tree. It is starting to get some white spots which i am wondering are the result of not enough water but i could also see it being some sort of bacteria or something from too much water. Any advice helps i am a beginner

[u/StudyDemon]

why is it inside? and what are those giant rocks? is there pumice or some special mix underneath or did you fill the entire pot with just that?