You didn't tell me in your PM that the filter was too strong
What filter are you using?
As mentioned above, you don't have to use a filter in a 2.5 gallon, as long as you do a 50% and 100% every week water change- or what I find works for me for my 2 gallons is just a 100% every 4 days- but that is me, you will find what works best for you, just as long as you get that 100% in each week.
If you choose that you want to keep the filter, then depending upon the type it is, you can baffle it. An aquarium sponge inside the outflow, held on by a clean rubber band will work to baffle it. You are basically just trying to make the current slower- you can also use a rubber band and tie on some panty hose on the intake valve on the bottom as well to help minimize the intake of water.
I already gave you some tips on the other subjects, but just wanted to catch you up on the filter thing, since it seems to be bothering him.