Yeah but I change out my res water every 7-10 days, so I'ts really not a problem.they work great for germing seeds to, I just put my seeds in,set the plugs in a tupperware container with about 1/2 to3/4 inches of water in the bottom place the lid over the top but don't snap it down, this works like a mini terrarium[SIZE=+0].....hope someone can use the info........grow your way to enlightenment[/SIZE]