Good line of questioning. I do have to confess my ignorance. I've presuming that SHMP is using a media filter consisting of sand (or garnet?) and activated charcoal, in the same vessel or in separate vessels. That would be as opposed to cartridge or sock filters. Based on my presumption of media filtration, backwash would be required. Backwash means that aquarium water would have to flow OUT of the system.
Any details you can provide would be appreciated. And that goes out to all those SHMP "investors", too. You have an open invitation to explain to me how SHMP operates a zero-discharge system.