i absolutely LOVE the design!! awesome! i may steal it someday reminds me of the joshua tree pics i have seen from monteray bay, what with that solitary ficus. i think the part that confuses me more so that any other is different water levels? in a closed environment like this, it's almost impossible to do unless you have everything completely sealed. one small leak and water levels will eventually equalize. example: if you have a 6" level on the left and plan on 3" on the right, that 6" section essentially needs to be a sealed mini aquarium. even the slightest little pinhole will cause the water from the high end to enter the low end and equalize it at about 4-5" (obviously a guess, but you get the idea). so i am now wondering if that is the issue you are having? i would love to see the tank empty of everything except the hardscape to see what's going on.