how to check a tank for leaks??

Before I did all the work of cleaning, I'd take it outside and fill it up with water and check for any leaks. I'd probably recheck it again after cleaning just to make sure, but I'm anal that way :)
 
I do that too but i just fill the tank with water,if there is leaks,i'll throw out the water and go ask for a replacement,if there isn't,do what we all do,cycle and add fish.
 
If you don't want to go outside, you can do it in a sink or bathtub.(If I went outside an did that, the water would freeze being that it is only like 20 degrees here.
 
AquariaCentral.com