Hey Dude! Welcome to Canreef.
I've been looking at building up a new tank to do a C2C external beananimal like you with one difference. I don't want the weir inside the tank. I am going to notch the glass and let it flow over the back glass into the external overflow. All things else are pretty much the same.
In terms of your weir height, the amount that you are flowing out of the tank won't really create a very thick film on the top of the weir (like mm thick), so that's not what you need to worry about with the weir height. What you need to take into account is: if all of the back ups fail and that return plugs, how much room do you have for the pump to fill you tank before it overflows. Most people have a 2 gallon buffer tank in their sump that the pump sits in, so you'd need to be able to take 2 extra gallons of water... for you it might be more or less. That math is easy. Weir film thickness are harder to calculate. Make your life easy.
For your tank and flow 3/4" drains will be just dandy, you could go to 1" to be on the safe side. In other set ups having too large of a siphon can cause weird behavior, the beananimal design is able to circumvent this and self-stabilizes (Herbie's do this too). Put a valve on the siphon drain to dial the system in. Personally, I'd just do 1" drains and 3/4" returns.
Is it unnecessary? Heck no, that's a sweet set-up.
Don't drill the overflows AFTER it is on the tank... that's asking for trouble. Drill each piece of glass flat on the ground and lay the tank on it's back to drill it. THEN glue it all together. Super easy.
|