I've been watching this thread for some time now and I must say you've done a wonderful job with your river tank. I wonder why the two GN died? Disease is most likely out, as the other GN are fine . . .worrying.
As a reef aquarist, I do admire your creative use of PVC; that and teflon tape are old friends of mine
![Smile :)](./images/smilies/icon/smile.gif)
. Never tried cyano glue in marine water . . .
With the size of the substrate and the down current through it, I would imagine the aereobic bacteria are having a heyday. What are the current water parameters in the tank? I would imagine no ammonia or nitrite, but nitrate could be all over the place; the strong plant growth will consume a good deal of it for its O2 content, but I was wondering about its level over time with the deep aereobic zone breaking down ammonia and nitrite to nitrate at breakneck speed. The space below the plate could be considered a plenum, and the anoxic zone (aka low oxygen area) could be breaking down the nitrate to elemental nitrogen, or to ammonium and back to nitrate, depending on the O2 there.
Just call me curious; I'd like to know the water qualities over time in a tank with a system like yours, iffin' you don't mind . . .
Dave
I dream of L-Numbers . . .