hmm i would say u want about 1/3 of the bottom perc chamber full of water if its a little more it wont be much worse when it gets to about 3/4 full is when i do an adjustment... and as far as more lung pressure... maybe but not much... i think that has to do much more with the actual size of the piece... sometimes it just takes a bit of time to learn to be a pro with a new piece... when i first started out with my bong i couldnt get the ridiculously awesome rips i can get now so just give urself some time to familiarize urself and your lungs with ur new equipment and u'll be killing it soon...