How do you clean an under gravel filter?

I just got a 3 gallon tank complete with under gravel filter (ya know, with the air pump and stuff) and it's working, but to be honest I have no idea how the filter actually does it's job and no idea how to clean it. It seems like it will be a horrible pain if I have to keep dis/re-assembling my tank each time. Also, how often should it be cleaned? Thanks so much!!

I used to have a 30 gallon tank with an under-gravel filter and it IS A PAIN to clean. You will have to remove the fish, remove the gravel and thoroughly wash it and the filter. The good news is that you don't do it that often - the filter pulls all the debri and waste into the gravel and trapping it in the bottom of your tank, keeping the area above the gravel clean. So long as you don't OVER-FEED your fish, and you replish the water as it evaporates (remember to add conditioner to the new water) you should be able to go for 1-2 years without having to change it. You'll know when because the water will turn slightly cloudy at first and algae will grow on the sides of the tank. Remember - DON'T OVER-FEED YOUR FISH!!!!!

Okay, I think the key here is short term cleanings. You can vacuum out the detruis with a siphon, they come in all shapes and sizes, every aquarium store has them. Clean out say, 1/3 of the gravel every week. You don't want to vacuum the whole thing at once, nor do you want junk to build up.On another note, using a reverse-flow undergravel filter will make your life considerably easier. You use a powerhead, and set it to push water DOWN the tube and up through the gravel. Then all the junk finds it's way to the powerhead sponge.

WASHIrr

pxtrials is correct... Also, disassembling your tank and doing a complete clean will kill the beneficial bacteria that help break down nitrates...