This is the filter intake. As the work progress, we decided to give it more camuflage so that it would not look obvious.
You can see from the side that the nook is actually a hole, here clearly seen because water level is currently under.
Once water level reaches target height, it will overflow to the filter chambers.
And here you can see once again the filter box.
Note that now you can no longer see any overflow route since it is already built within. The chambers are closed with a thin plywood for house constuction (stairs for exact). I plan to cover up the chambers later on but with something freely breatheable, wrought iron grill for example. Such grill bars would cover up the ugly view of a filter and would be a great surface to place some pots of house plants (then you have the filter box "dissapear").