What an awesome project this will be! I'm gonna be following along with bated breath...
I'm not sure if I am saddened that the tiny little house I retired into doesn't have the room for me to even consider a build like this...or maybe I'm relieved.
What's the deal with the shape? What is that little square offshoot on the left at the back? Is that going to be a separate partition? Filtration compartment? Or...? Did you pour the slab floor especially for this?
I snicker a bit at "build threads" that treat the filling of a 50-gallon tank and installing some sand and a filter as though it were a major construction project. And then...there's this! Walls of concrete blocks...bags of cement piled high...rebar...I'm tellin' ya, my fingers are starting to twitch.