They leak. End of story. You have to work over a sink and wear gloves if you don't want drips everywhere. Some tanks are worse than others depending on how well matched the lids are to the bottoms. I have some that barely leak and others that gush. For short timed processes like C41 I prefer to dip n dunk in an open tank in the dark with each step in a separate tank. I agitate with the little wire dipsticks you can get with them lifting the reels up and down in the tank.