You should blacklist glowstone from the pulvus. with the bonus upgrades you can pump glow stone blocks in, crush, craft and repeat. getting bonus glow stone in return.

You're right. you can dupe glowstone. but it's expensive.
I tested it with 8 bonus upgrades and 8 efficiency upgrades and I needed 20 pieces of coal to turn 16 glowstone blocks into 32.