Link tubing from main tank to sump. Create a siphon with tubing. Tubing will be of a certain diameter to match return rate of the canister filer which will pump water out of the sump and back into the main tank.
Protein skimmer is an ASM G2 rated for 200g
Canister filter is a Marineland Magnum350 rated for 100g
75g main tank, 35g sump. After live rock I expect roughly 70g total water in circulation, maybe less.
Am I missing anything?