"l33t" is a corruption of "elite", with the 3's substituting for 'e' (giving you "leet"). Basically, it was heavily used by social misfits with a limited vocabulary to make themselves sound cool. Kinda like me in high school.
Backflow valves restrict flow a bit. He's better off with the liquid seal that he has. No flow restriction.
How noisy is that pump? It looks big enough to sump pump a basement!