PVC overflow

[AndrewMack]

I have seen a few pics of these PVC overflows and wanted to know if anyone knows how to make one? How they exactly work? and what size PVC= so many GPH and if the overflow is pushing 600gph and i only have say a 400gph return pump will it empty my tank or lose suction completely?

 

[buyobuyo]

the overflow will only flow as many GPH as your pump will flow. Even if it is designed to be able to flow more.

There are some good calculators here (http://reefcentral.com/calc/) for overflow pipe size and such.

 

[Rallysman]

Hit me up on AIM and I can take you through it step by step.

Have you checked the sticky at MFK? It covers pretty much all bases.

 

[AndrewMack]

yea i checked it just didnt understand really and it only had one picture. My55g will be OS so i need to get more water so i figured a big 30-50gallon wet/dry will help

 

[Rallysman]

here is another pic. The red represents where the water will be when the pump is shut off. Perhaps you can make more sense of this one.

The short tube is what determines the water level. If you want the level higher, make that tube longer. The part with the valve connects to the sump. The tall is a vent so it can act as an overflow rather than a true siphon.

 

[AndrewMack]

so if i make the tube so its only about 3" from the surface of the water then if my power goes out on 3"s of water is drained from my tank? correct

 

[Rallysman]

if you make the tube where it's 3" below the rim of the tank, the water line will be 3" below the rim of the tank. Imagine that there is a hole drilled at the same level as that tube----that's how it will act.

 

[AndrewMack]

ohh so it needs to be just below the surface?

 

[Rallysman]

If that's where you want the water level to be, then yes

 

[rohnds]

Rallysman, I have question about the above picture. I am to assume that the whole thing hangs on the back of the tank with the U section inside the tank.

During a power failure, does it keep the siphon?

When the power comes back up, does it return the water flow without any help.

Thanks for any help you can give me in my own DIY project.