Floyd R Turbo
Either busy or sleeping
I'm not a big fan of internal overflow boxes. I think they are too limiting. You end up forced to use junk durso standpipes and the like.
You don't need to make a complicated built-on overflow system. You can just have the tank made plain and then drill a pair of holes for 2" bulkheads on the back and make an internal & external overflow box held on with the bulkheads. Dimensioning the box out correctly to handle your flow is a simple calculation, and in case you decide say that you want the internal overflow box to have teeth or not have teeth, this is a simple change (in fact, you can make an adjustable fence that screws on to the weir with thumbscrews, etc, easy peasy and have it both ways)
It is really simple when you do it that way. No messing with cutting a weir on the back of the tank and then needing to re-inforce it with the external box, though you can do that too, but drilling a few holes does literally nothing to the integrity of the tank.
You can have a coast-to-coast overflow along the entire back of the tank (all 8 feet) and it would only stand off 2" off the back and be about 7" deep from the top of the water.
Then, you can place the external overflow box anywhere you want, and it does not have to also be 8' wide, it really only needs to be 2 or 3 feet wide, will stick off about 6" off the back of the tank, and be about 9" or so deep. So you can offset that to one side, and you don't need to get someone thin and gangly to reach in there for you. If you do that, of course, the opposite end of the overflow box will need some support, so you just drill another hole for an additional bulkhead at that end and just cap that one off.
You don't need to make a complicated built-on overflow system. You can just have the tank made plain and then drill a pair of holes for 2" bulkheads on the back and make an internal & external overflow box held on with the bulkheads. Dimensioning the box out correctly to handle your flow is a simple calculation, and in case you decide say that you want the internal overflow box to have teeth or not have teeth, this is a simple change (in fact, you can make an adjustable fence that screws on to the weir with thumbscrews, etc, easy peasy and have it both ways)
It is really simple when you do it that way. No messing with cutting a weir on the back of the tank and then needing to re-inforce it with the external box, though you can do that too, but drilling a few holes does literally nothing to the integrity of the tank.
You can have a coast-to-coast overflow along the entire back of the tank (all 8 feet) and it would only stand off 2" off the back and be about 7" deep from the top of the water.
Then, you can place the external overflow box anywhere you want, and it does not have to also be 8' wide, it really only needs to be 2 or 3 feet wide, will stick off about 6" off the back of the tank, and be about 9" or so deep. So you can offset that to one side, and you don't need to get someone thin and gangly to reach in there for you. If you do that, of course, the opposite end of the overflow box will need some support, so you just drill another hole for an additional bulkhead at that end and just cap that one off.
