I asked this question a couple of month ago, I suggest you read it first so you know the context.
I have a 15 gallon tank with 10 neon tetra, 4 zebra danios, 2 endler and a bunch of red cherry shrimps (~30) fully cycled with an aquaclear 30 and a small double sponge filter. As you can see it's getting a bit cramped inside the 15 gallon so I have decided to upgrade to a 75 gallon tank. As it is, I have the 75 but don't have any other thing for it (no filtration, no heating, no lighting). Since the fish move happen at the same time as I physically move, I would like to avoid moving the population twice in less than a month.
So my question is, can a large aquarium be under filtered but also under stocked and maintain his equilibrium?