I don't think there drowning because there not even pipping the shell? Most of them are dieing around day 18-20 I think because some still have the yolk and some don't? So from what I've been told there dieing a few days early not while trying to hatch. I have also already checked into the sea level thing and I'm in Georgia so that's not my problem. I dunno ready to give up and just sell hatching eggs. Lol
I am so sorry about your hatchi tried to send you message on the thread the other day and it didn't send it for some reason. Anyway, don't give up! Keep trying. It sounds from your post that you are doing everything right! Hang in there!