When I used them, I used them as aeroponics chambers. I put endcaps on the pvc and drilled holes into which I ran a 3/4" pvc spraybar (pvc with a bunch of tiny holes). The larger holes in the large pipe held mesh pots filled with Hydroton media. I ran a powerhead from the fish aquarium into the spraybar with a return. The fish
poop water sprayed through the bar, aeroponically saturating the plant
roots before draining back into the tank. Mine was not set up long
enough to determine longevity but it worked great while I had it set up.