Wow.
This thread has degenerated into something atypical of the fish-nerd comraderie I usually see.
BeAn has been a fantastic contributor for the years I've lurked on this site. He is courteous, knowlegable, and helpful. I saw no self-agrandizment in his post, and he even cited the original herbie post in the first post. You people need to get off your high horses.
This is a straight forward explanation of a simple and effective solution to a problem we all face to some degree. How many "noisy drains, help!!" threads do you see on here a day?
If you're concerned about the environment, a few extra pieces of pvc won't change the world. Perhaps you should get out of the hobby considering the resources you "waste" and the innocent creatures you torture for your own selfish enjoyment. Not to mention the energy you wasted posting a response to this thread.
On a more topical note, yes, the end of the siphon drain (and only the siphon drain) must be submerged for greatest silence and lack of bubbles/creep. If only water (no air) is coming down the pipe, no bubbles are made if the end of the pipe is under water. Does a garden hose underwater make bubbles? Only when you first turn it on, before all of the air is pushed out. attaching another drain to the siphon will introduce air.
Clay, my sacasm radar had you pegged!

Noone could be
that ignorant/rude!!
end communication