Dear Akita
The problem is sometimes people who don't know, venture opinions as fact. The pressure question was not clarified by your adding the air pressure as if the other posters were in error, or forgot it, and it doubtlessly confused others following the thread. Hence my annoyance and sarcasm.
The pressure of air must be added and then subtracted again because it acts equaly on both sides of the hull (unless the hull is sealed somehow to exclude it i.e. vacumed)
Please reply civily, or on the other forum, or by all means, converse with your bath bubbles.