I know it hasn't been all that long yet, but do you have anything you wish you'd built differently? Aside from the difficulty of finding black glass.
For example, I was thinking I'd try putting the valve assemblies on the overflow system underneath, farther down the overflow pipes. They seem like they'd be a bit hard to reach if I ever wanted to, unless I could easily reach over and around to the far side of the tank.
I'd imagine with the way this overflow drain is built, it wouldn't just be silent, it would off-gas very little CO2 compared to a typical overflow which splashes all around inside the drain pipe, mixing with air as it goes.
I should have gone with the smoke glass, or found a shop that did have black glass.
As far as the gate valves, there is plenty enough room behind the tank to easily reach these. That said, you want to be strategic about which side you put them on if, for instance, the tank is going in a corner. The issue with putting the valves under the tank is twofold:
1. It requires extra unions closer to the top of the overflow should you want to take the tank off the stand. Additionally, you now have no valve to close to prevent splashing water from spilling on the floor if you move the tank off the stand. This is admittedly minor as very little water should be left in the overflow when the pump is turned off.
2. More importantly, if you put the valves under the stand, you can't see how the water in the overflow is reacting as you adjust the valves. Dialing in the proper valve openness becomes a 2 person job, which is a bigger hassle than you might think.
This style drain is not ideal if you want your tank flush against a wall. That said, the space you need between the tank and the wall does not push the tank so far out that it becomes obstructive unless you have a huge tank and need 2" drains or something. I know I will never own a tank that big... If you put unions on either side of the gate valves you can easily angle the valves such that they take up less space behind the tank as well. If you don't use True Union valves, I highly recommend using PVC unions on either side so the valve is reusable.
I should have also spent more time on the hardscape. I honestly feel like I could have gotten a lot more out of it. That said, engineers tend not to have the most artistic eyes.