Welcome to AA!
It is true that a balloon molly likes a lot of swimming room.
But... let me tell you about my experience. I had a 30 gallon tank of malawi cichlids that was way overstocked and too small for 'em. People here on AA kept telling me that they needed more room. I looked at the links they provided and concluded that I should find them better homes. I advertised the fish and a woman said she'd buy 3 of them. After I gave them to her I asked what size tank she had. It was a 30 gallon. 8O I gave the rest to the
LFS. The guy put them in a tank and I watched all the other fish in the tank bully and attack my fish.
I felt just terrible. I felt like I had betrayed my fish. They weren't in better homes.
I wonder if they'd have been better off staying with me even if they were overcrowded. I still miss them.
Since you have Hoover, keep him. He sounds like a cool fish. 8) Giving him back to the
LFS won't guarentee him a better home. In all other ways you will take the best care of Hoover. You have him in a lovely planted tank and he'll do ok. Maybe keep the tank lightly stocked so he won't feel crowded.
As far as other fish, I like cory cats the most. They'd love a planted tank. I got some pygmy cats but because they were so small, I could hardly see them against a natural substrate. :| Get maybe 3 regular sized corys.
good luck
coolchinchilla