I would go with no top. It lets more usefull light get to the stuff in the tank, keeps heat down and allows for a better gas exchange on the surface of the water from what I've heard.
I go topless also mostly to help control heat as my canpoy sits right on top the tank. With the glass top on it raised my tank temp 4 degrees, making it way to high to be safe.
No top for me on my 20 Long. My lights are raised above the top as well. If you have fish that you are worried about getting out you can use eggcrate and keep the propper gas exchange and still let a lot of light through. But IMO no top is the best way.
Do you have young kids? If I left my glass top off forget it there would be Little people swimming in the tank not to mention all the help feeding my daughter would do..And I'm not just talking fish food.:nope:
I agree. I use to keep the top off my 72 bow tank until I found my 3 year old using his plastic fishing pole one day. He had the line and plastic hook in the fish tank!!!LOL!!