I have not looked into building something like this before but there are a couple of things I would research prior to committing to using the basement floor and wall. The basement wall and floor are likely not attached to each other which means where they meet could be subject to expansion and contraction which can damage a waterproofing seal. I also see some efflorescence on your basement walls near the bottom corners which means that moisture is bringing salts through the concrete. The efflorescence on its own is not an issue but if you are going to be waterproofing that concrete it might be more susceptible failure due to the moisture present in the concrete at the time of application or during a time where the water pressure in the ground is higher than the water pressure in the sump which could cause a waterproofing failure. If it can be avoided I would also not have any water or plumbing connections over the sump or the displays as a plumbing leak could devastate a system. The only other concern would be the temperature of the wall and floor during the summer and the winter. My basement stayed in the 60's year round before I had my aquarium running. If you have the same scenario where your basement walls and floors are typically cool year round then it might act as a heat sink and cool your tank water to the point where there is a higher demand on the aquarium heating system. Again these are just some things I would research as I have not built something that would incorporate parts of my basement floor and wall to hold water. It took me a little over two years to get my system running and I spent a lot of time researching and planning. I would take your time in building such a large system and ensure you have a good plan for humidity control in place before anything is filled with water. I look forward to seeing updates on this build.