The metal beams are original to the house. One that runs through the fish tank room (which is basically right smack dab in the middle of the tank) supports that column you see the tank is built around. The other is 5-6 feet further, or about 2-3 feet from the "left" end of the tank. The microlams support the "right" end of the tank. Those metal poles you see embedded in the framing hold the microlams up which then hold the original floor joists and the additional floor joists added for the tank support. The other end of those joists lay on top of the existing metal beams of the house. All the framing you see really has nothing to do with the tank support, it's all part of my basement finishing project.
Very cool---but I honestly thought the new beam underneath was for the tank. That's why I asked. Cool set-up and good luck with the build !