Most hoods have openings in them for the filter, heaters etc.... so there is a space for air to circulate. I wouldn't think that you 'need' to take off the hood at any point other then for maintainence. If you leave the lid off all the time you get a lot more evaporation. Never mind the occasional ''leaps of faith" that fish make, to see whats outside their tank...
Even saying that, I have one tank I leave the hood off all the time, but that is because I'm afraid that both the hood and my cat are going to fall into the tank! lol
Hi. Don't worry about asking silly questions. We'll answer anything around here!
I also keep my hood on. In addition to all the other reasons already listed, a hood on the tank, to me, seems like fewer contaminants from the surrounding environment will get in. Is there a particular reason you want to take yours off, or are you just curious?
My cats all try to drink the tank water when I am doing maintenance. They much prefer the flavored water to the sterile stuff in their bowls. Of course, one cat has been scared to death by an angelfish who thought that flicking tongue looked too tasty to resist.
Where would we put our mail if we didn't have hoods on the tanks? The hoods keep the junk from the shelf above it from falling in--I don't want my car keys or pens in the tank. And how am I supposed to keep things out of my daughter's reach without the hoods?
I have to keep mine on otherwise the fish are bound to go flying, I went out of the room for like 2 minutes once and found that one had already decided to jump out and my mum thought I was joking when I told her they might jump if I left it off.
The top of my hood also seems to get very dusty so I don't think I'd want all that going in the water instead.
I keep mine on for a number of reasons. First, here in the desert I can lose over five gallons of water a week from evaporation, and that's with the cover ON. Second and more importantly, I don't want my fish eating any insects that may have been treated by the Orkin man. Eating poison bugs will kill a fish fast.