the way it was explained to me and many other member's is the bridge is '' U'' shaped with threaded end's so it can be caped . fill the tube up first then cap it . turn the tube over place an end in each tank with the CAPED END'S IN THE WATER, unscrew the cap's and bamm u got an aquarium bridge very simple if you learn the mechanix's of it... it work's best with a clear center pipe(so as to view the fish swimming throw the pipe) the bend's can be plane white pvc pipe no biggie. this does how ever increase the volume of both tank's drain water out first before removing the bridge or both tank's will over flow..... ps montior your water level to if tank get's to low from evaporation the tube will empty out..
mind boggling . and one more thing forgot to mention drain off some of the tank before you place the bridge in and uncap it . the added water from in side the bridge to an allready filled tank , you can figure it out from here!!