Almost. The latter part is correct.
We're actually pumping sea water from depth unfiltered, bringing it into our system. We exchange it with the tank about once an hour and then we collect the solid waste from it. We move the solid waste to land and then the rest of the water goes back into the ocean. It's a fairly simple system. It doesn't involve high technology, like a biofilter or ozonation and so on. That's why our energy costs are so low as well. We don't need to be using those systems.