At 7inches I wouldn't be extremely concerned yet, sometimes peacock bass take a while to settle in. I once moved some growouts from a 75g to a 125g across the room and they stopped eating for a couple of weeks. I was worried and posted a thread on it but they eventually started eating.
Have...
I would empty the substrate out, clean it thoroughly and tip the tank up so that the compromised seam is down. Use acrylic square stock and weld on and fill the seam.
You can't put a heater in a aquaclear....or anywhere near as much biomedia. You can't upgrade the pump for more gph either. Check out the what's under your tank thread, there's plenty of people that have neat clean sumps.
Ken is a guru with the pond/large aquarium filtration stuff. I've had so many conversations with him about that stuff. There are a few of the ray guys that are great as well.... Just off of the top of my head Reedmaster, vamptrev, jk47.