Trust me, if I had know this before it would have been done. I've never read about this, and I've done, as I've already said, a lot ofresearch. In addition to the written research, I've seen plenty of videos on youtube and I can't remember any of them adding a drainage system like this.
Anyway, it's too late now. I haven't got any frogs yet, and I'm glad that I haven't because since I've finished the tank, I've encountered a few problems that would have been extremely hard to fix with the frogs in the tank.
I can work on the tank, but not to the extreme of drilling a hole in the glass.
When my water reaches the top of the clay bottom, I'll try syphoning it out with the aforementioned pipe. If it doesn't work, I'll have to take all of the decor, substrate and clay balls, and build a mechanism similar to what you have said.
This will be a pain, since my substrate has already been seeded with springtails and woodlice![]()