Hey steve, I'm still waiting on all the parts but mine will be more of a newbie version of his as i don't have the room for multi barrel filtration. I will be running an FX6 that's strictly mechanical which will output into a 20 gallon brute with k1 micro in it with air stones to circulate the k1, which will use 2" pvc pipe to overflow drain back into the 150gallon stock tank. I will try to post pics of my attempt to make this. I am just waiting on all the parts to come in.
Looking at the DIY canister filters, I honestly don't have faith in tupperware snap seals to offer reliable sealing for a pressurized canister filters. That's just me. Even commercial canister filters are prone to leakage with sturdier clamps and seals.
As for food grade plastic containers, i have been reading up on the plastic of brute containers and on reefcentral a member posted he picked a few up and on the bottom of the container, rubbermaid actually indicates "Food; White, Yellow, Grey". The other colors of brutes have the risk of leeching the dyes into the water I believe. I was looking into brutes due to the flexibility of them being available in a variety of sizes. I don't have room for a 55gallon food grade barrel nor do would a 5 gallon food grade bucket from home depot be big enough.
Then again, I was housing my turtles in a 189L rubbermaid roughneck and another rubbermaid tote prior to that without verifying the plastics were food safe. Did not know at the time and many turtle websites suggested rubbermaid totes as an alternative to glass aquariums lol.