Floyd R Turbo
Either busy or sleeping
It depends on your overall flow rate, and the number and size of pass-through bulkheads you plan to use.
If you're over 3000 GPH I would use two 2" bulkheads or 3 1.5". If under 3000 GPH you can use two 1.5" bulkheads.
You could get the inner box as shallow as 2" front to back if you put the bulkhead nuts on the inside of the box and the flange in the external box.
Generally your inner box height is giong to be about 8" total, starting below the rim of the tank relative to the outside lowest point of the trim)
If you're over 3000 GPH I would use two 2" bulkheads or 3 1.5". If under 3000 GPH you can use two 1.5" bulkheads.
You could get the inner box as shallow as 2" front to back if you put the bulkhead nuts on the inside of the box and the flange in the external box.
Generally your inner box height is giong to be about 8" total, starting below the rim of the tank relative to the outside lowest point of the trim)