Every year the same thing worries me also.
Every year I empty the pot, clean it out real good with water, spray my hibiscus and sweet olive with insecticide and repot them with clean new Miracle grow potting soil, and run them up to the room that I have for them.
Every year after a little while, mabey a month or two, I see little bugs flying all over the room where they are.
Last winter my expensive hybrid hibiscus that I had for about 3 years developed a fungus.
It was sooo bad, that I had to get rid of it.
Good luck with your banana. It is a good thing you are young, mabey you can still carry it.
I have to keep my bring in plants small now.
I am in my late 40's and unable to carry heavy conatiners and plants anymore.
By the way, do you have bananas at all on it?
Just curious. It sounds awsome!
Good Luck!

Hi Butterfly! I might try to 'segregate' the plants, hopefully in different rooms maybe. I read that if you put 1/2 inch of sand on top of your soil that keeps fungus gnats away. I soaked my banana in water for 24 hours, that hopefully will kill any bugs in the soil, not sure about eggs though.

I'll try to post a pic of the banana later, it's only 3 feet tall, it'd be taller but I have it in a smaller pot (like a 10 inch one).

If you have big plants and have trouble carrying them (I know what you mean, just toting the banana is tough to do, but I have to repot it), some plant catalogs and stores sell flat plant stand thingies with casters (wheels) on them, maybe you could get something like that? I had one banana, and it's got 2 pups now. :) I just hope my indoor ones don't get any diseases (crossing my fingers).

when I bring pots inside I first set them in a plastic bag then sprinkle moth balls in the pot--then-- after that you close up the bag overnight. This usually works fine for me.
If something buggy happens to hatch later on I can repeat the procedure. I also can save the moth balls and re-use them or leave them in the pot..but I do not have any little children or pets that are likely to find my moth balls if I leave them in the soil anymore --so I could probably just leave them in the soil for winter. Mary

I drench the soil with diluted orange oil because I have problems with ants getting in my pots, and I don't want them in my greenhouse or my house. It really works well.