Algea likes moist so if you have algea on the perlites you can let the soil dries a bit , they will not grow more but the perlites will remain green.
In your case we can see algea in the bottom of the pot , the pot is tranparent so the light can get inside of it , so light + moist + soil = perfect combo for algea development.
The solution is to water less but more often to let the soil dry between each watering like that the algea will not have what they need and to switch pot or to cover yours with some foils ( not aluminium ) to block the light , you can also paint the pot.
for the cracking leaves here is a likn to the "plant doctor" it will allow you to auto diagnosis your plant
https://www.growweedeasy.com/cannabis-symptoms-pictures