Help me design a Herbie Overflow (nano)

[yongpanda]

I'm currently planning on a 12" cube reef tank build. Instead of going with the glass-holes overflows, I figures that a DIY herbie overflow would work better in terms of noise or the lack of when using a herbie.

Since the overflow will be used on a relatively small tank (7.5gallons) with a Vortech MP10es for flow, I figured that 200gph for the overflow would be a good amount.

So enough of the background of the thing, time for the questions...
1) To achieve a 200gph with the main overflow pipe, what is the recommended diameter for the piping? (I know I can control flow using a ball valve, but I'd like to stick with the smallest possible diameter to reduce the size of the actual overflow box being used).

2) Is it okay to have both the main and secondary (emergency) drain pipes to go straight up. In other words, do I need elbows on the pipes? It'd be nice if I could just have two pvc pipes of different length in a overflow box; reducing the overall size of the overflow box.

3) In regards to the second question; If I don't use an elbow for the secondary/emergency drain pipe, will it make gurgling sounds?

4) For the teeth on the overflow box; does the size of the teeth/height affect the flow rate of the entire overflow box?

5) I know both the main and secondary drain pipes lead to the sump, but is it okay to have them join together maybe using one of those pvc pipes that are shaped as a T.

6) what does head height refer to when calculating the GPH using the diameter of the main drain pipe?


*More questions to come..*

 

[yongpanda]

Where the overflow gurus at?!

 

[NanoReefWanabe]

1> i would say 3/4" is the minimum i would use for any drain, well 1" would be but i see where you are coming from on this tank..

2> yes both pipes can be straight no need for bends and elbows, heck you could screw a strainer into the bulkhead for the siphon line, and leave the other one high enough water cant get out of the tank...control the water in the box with the valve.

3> yes, but you want it too...that way you know there is a problem with the main drain...

4> yes teeth drastically reduce the skimming capacity of the overflow and also greatly increase the height of the weir...FYI there is no need for teeth on the overflow

5> NO. leave them separate or you will create turbulence and noise in the drain lines

6> head height is the height the water needs to be pushed from the sump to the display tank, measured from the top of the water surface in the return chamber of the sump to the top edge of the pipe above the display tank (if you are going over the top of the tank) if your return pipes are submerged it is the distance from the top of the return chamber's water to the water level in the display tank.