Try using null essence; it makes light farming much faster. The pristine light will be useful later in the game.
Null Essence just sucks.
It's literally "I paused the game 'cause you weren't looking at it" until you deal with it long enough to get to "I paused the game 'cause you weren't looking at it, and now I incentivize you not to look at the game by 5%".
It's actually the WORST feature of an already bad game design. The "don't play my game, so that when you do play my game it won't suck"-feature. That's literally all it does for the player.
It's the worst.