Mechanics of DIY overflow building one. Questions

[Gigaah]

I have some questions about this acrylic overflow I'm making.
Picture attached.
Basicly measurements for the syphon i was thinking 1"x8" with a nipple on top for my powerhead to keep it primed.

My questions are from designs I've seen on the internet. The sections in red I'm not EXACTLY sure the purpose of. The box in the water I understand skims off the water level and adjusts so you can pick the level of your water. but do you need that? maybe i don't exactly understand its full purpose.
2nd: The divider in red. What is its purpose? and if its supposed to be there how high(perhaps in relation to the syphon) should it be?

any help is appreciated. The cost of the acrylic is really low..like 10$ for home depots .093 thickness. which IS thick enough.

also are there any sort of calculators out there to tell me the syphon size to flow rate? rough seat of my pants calculations tell me the 1"x8" is way big enough but is it too big..is the possible?

 

[bjohanson1234]

The box inside the water is to keep set the height of the water inside the tank yet letting the syphon to still be below the surface of the water. In the event of a power outage, the box gets drained of water not the tank.

The Divider inside the overflow keeps the one output end of the syphon under water. This prevents it from losing the syphon. Not sure on the height of it though.

 

[Reefrookie]

Your flow rate out of the box is determined by the size if the bulkhead you drill in. Your tank should handle a 1" bulkhead, which is about 600 gph

 

[Rcchanlder]

if you do it bend the acrylic. dont cut and glue. you will never get it air tight again. trust me. ive been leak proofing mine for weeks

 

[Rcchanlder]

also. a one inch gap is a lot. you would be more likely to get air build up. and make sure that the pump you use is strong enough to get the overflow box started. i ran into that problem as well. if you want to know more of my mistakes i would love to help you keep from making some. saves some $$$. The hieight of the divider on the inside of the box needs to be higher than the lowest part of your syphon. this will ensure that the syphon stays primed at all times.