Help me build my 55 gallon reef

Sorry, I should have elaborated. You NEED the box on the outside, as that is what keeps the system primed. Both sides of the box have water in them (up to the same height on both sides), including after you shut the return pump down. Then, once you start the pump back up, it immediately begins to siphon down to the sump. Without this outer box, every time your pump shut off, you would need to manually start the siphon all over again.

 

How would something like this work? http://www.3reef.com/forums/i-made/non-drilled-tank-alternatives-my-diy-overflow-140523.html

Instead of the vertical PVC, I was wanting to use a more aesthetically pleasing box. I don't see why drilling, as opposed to having the pipe hang over the rim, would make any difference.

 

Because both sides (PVC inside the tank, and PVC outside the tank) retain water after the pump turns off. That is the key.

The way the siphon works is as water flows over the U-tube and down the drain, it needs to "pull" the same amount of "media" (either water or air) with it. Since the side in the tank is full of water, it pulls more water. When the pump stops, if you just had a straight pipe to the tank, it would siphon until the water level was below the strainer of the overflow box. Then it would be pulling air instead of water, breaking the siphon. If water is able to be trapped on the drain side like in Todd's design, the water drains until it is at the same level on both sides. Once both sides reach equilibrium, they both retain water and the flow stops. When the pump is turned back on, it pushed the water in the overflow back up the pipe and starts the siphoning again.

I hope this makes sense!

 

Gotcha.

Could I use his plumbing design and use an overflow box instead of the PVC overflow box he used inside of the tank?

 

At that point I would just buy a manufactured unit. I myself have an Eshopps 1000 GPH box. Through 7 months, and hundreds and hundreds of start & stops, it has never failed to siphon. Unless you build in protections (have a high float shut off the return pump if the siphon failed), I would not attempt to do your own.