I usually put a powerhead down a lil lower to keep water flow. Then just siphon right out of the display tank to where my rocks are barely under water. That's 20g of water. And then throw in a maxijet 1200 into the fresh salt water drum and have the water go into the display tank. I've been reading on r2r about wet skimming water changes. Just have your skimmer run wet to pull the water out and then just put fresh saltwater into your ato bucket to keep the salinity correct.