I hatched out 17 clutches last year using hatch-rite only ever added water to 2 egg bins..plan on hatching 27 this year.....if you are having to add water then maybe its the size of air holes or the amount of air holes...heat added to water and to air causes it to evaporate...I use a standard plastic shoe box with a single 1/8'" hole drilled in one end....Go to NERDS website and watch the video of how he does it....the guy hatches 100s if not 1000's of BP's every year with Hatch-rite
Travis
Lair of Dragons