I installed four LVLs (1-3/4" X 11-7/8" X 8') supported by a 4" steel I-beam over two 3" round steel lift columns. I installed two 12" footings to support the steel columns. I am now waiting for my aquarium to be made and delivered in about 12 weeks.
That looks so much better than I had envisioned before! I guess I didn't really understand. I bet that was a job jackhammering? out the floor for the posts.
I hired a foundation company to install the support system. They used a jackhammer, shovels and a wheelbarrow to cut, dig and remove the old concrete and dirt. It got a little dusty down there, but they did a pretty good job.
This is a follow-up and a thank you to all who have advised me on this project. My new aquarium is now installed, up and running. Attached is a photo of the aquarium.