Hi, must agree with a lot of the stuff on here.
Firstly, dont waste time and money using chemicals to get rid of the ammonia, you need to do 90% water changes daily and that will be much better for the fish.
Secondly, Id be worried that if the mbu has anything nasty it will infect the other fish so maybe you could seperate them somehow? Habve you got a super-sized quarentine tank anywhere?
Finally, I know you love your fish and think you are doing whats best for him, but imagine being a toddler locked in its bedroom, then adding a living room when its a teenager, then a kitchen when its an adult. Thats in effect what you are doing only upgrading the tanks when you have to.