Tube Trap Tips for my studio apartment?

I have a studio apartment home theater, but even with 2 Rythmik LV12R subwoofers, I can barely feel any bass at all due to the room modes produced by my 16' x 15' room. I have tried every single combination of placements for the subs, no dice. Since I can't move at the moment, I figure my best option is to use bass traps. Now tube traps looked really interesting, and I was thinking of building some of these: http://www.teresaudio.com/haven/traps/traps.html I was going to use this fiberglass: http://www.buyinsulationproductstore.com/servlet/the-485/Certainteed-Fiberglass-FSK-Duct/Detail


I was wondering, does it matter that these would make 4' high ones, rather than the conventional 3' high tubes? I'd like to think this would be beneficial, since stacking 4' tubes would go closer to the top of my ceiling, which would provide better coverage. But I've also read that the height of each tube determines the frequency range it handles, so I was hoping someone could shed some light on the matter for me.


Also, that fiberglass is 1 1/2" thick, rather than the conventional 1"- would that be a problem? I was thinking of making them 20" in diameter, by the way.