Help with overflow size

[vincephuket]

Dear all,

I am getting a custom nano tank built, will be 38 g. As I cannot have a sump I decided to get a filter built on the back, like the all in one style tanks can you find on the market.

The tank style will be like this:

now my question is, considering that my return pump is about 500 gah, how long should be the teeth section (overflow) and how big the gaps between the teeth? The water level is 2” below the top of the glass.

please help me, I am struggling with this. I know I should avoid teeth, but do not have any other choice.

thanks in advance

Vince

 

[Ron Reefman]

A 1" diameter pipe fed by gravity flows about 900gph. Figure the square inches of a 1" diameter pipe and then the square inches of the holes in your overflow.

When I did mine, I found that the friction of the smaller holes of the overflow meant that I had to just multiply the square area of the holes by 1.5 compared to a 1" pipe.

If your flow is too much, you can always block some of the flow from behind the weir holes.

Here you can see the holes I had to drill in order to flow 900gph.

 

[vincephuket]

Thanks a lot Ron Reefman, in the end I drilled a total surface of 15 cm, should work

 

[Ron Reefman]

If you can, I'd suggest a test before you commit to doing a saltwater set up. I drilled extra holes and then enlarged holes before I got it right.

 

[vincephuket]

If you can, I'd suggest a test before you commit to doing a saltwater set up. I drilled extra holes and then enlarged holes before I got it right.

According to Reefcentral calculator for 350 gph I need a linear overflow surface of 5”. To be safe I made 6” (15 cm). In case it is too much I can adjust the return pump (Sicce syncra 3.0) or plug some holes.

Well surely I will test it before putting salt water, rocks or whatever .