I started reading on my first morning coffee, and I liked the "going to do seals". I had a momentary vision of a tank with ice flows and marine mammals.I have changed my mind. I think I am going to get someone to help me shift the tank and I'm going to do seals, maybe paint a background on it. And set up a sand bottom species tank for red head tapajos - 55 gallons with a lot of sponge filters, I'd guess I could keep 2 or 3. Don't know where I am putting the succulents next winter, but I spent thousands fixing the foundation so I can have a 2nd 55 now.
Red Head Tapajos are wonderful but you'll be in for a lot of water changes to keep adults healthy in a 55. I traded mine away from a 75 after a couple of years. If anything happened and I missed a water change even by a few days, they showed it.