I managed to find out myself how do do colour schemes, it's on the shader place on worlds.txt
But now, when using some color schemes, the water is grey
Not in all of them, though
Default one works well, some others like amidst also work well
but flames and sk89q both have water being grey for example
according to the screenshots on the wiki, water shouldn't be grey when using them
Example:
https://cdn.discordapp.com/attachments/1125898013781540894/1125995703190171688/image.png
same area loaded in a map using default shader:
https://cdn.discordapp.com/attachments/1125898013781540894/1125995805774467173/image.png