Need so input on over flow

[acrouse]

I'm getting a new tank and am wanting to get rid of the HOB over flow box. I'am thinking of drilling the tank with 2- 3/4 to 1" holes high on the back and install some bulkheads and use that for a overflow to the sump. The questions I have is

1. Is there any down falls to dong this other then the risk of drilling the glass?

2. I would like to have around 1200 to 1500 gph in flow can I get that with 2- 3/4 in holes, or do I need to go larger than 1"?

3. How loud will this be?

4. If anyone has done this could you please post a photo, so I can see how you did yours?

Thanks in advance for all your help.

 

[Dave Dunbar]

Hello
I use to live in Ackworth. If you want that much flow go bigger like 1 1/2"x2. A 1" bulkhead will flow only about 600gph. When you go out the back dont go into an elbow use a "Tee" so you can make a riser for air.
http://reefcentral.com/forums/showthread.php?s=&threadid=1310585
Heres a good post about overflows
Dave

 

[Double-J]

It's not that simple... The reason for the "overflow" is to surface skim. The bigger the area of surface skimming you do is better. just putting a hole in the back of the tank doesn't give you much surface area. Now with that being said you can do a few things to make it work.

1) one would be glue a couple pieces of glass and make a box at the top of the tank like this: (one long box with hole cut in the back)

<img src="http://www.shallowreef.com/display_image.php?id=445">

Or you could cut the holes down from the tank then 90 degree them up and put 3/4" to 2" bushing or some sort of big drain top that way you are skimming "x" amount of surface water.

Also 1.5" bulkhead will drain ~1200 GPH. unfortunately adding 3/4 +3/4 doesn't add up to one 1.5 bulkhead. If you want to flow around 1200 I would consider 2x 1" bulkheads if not 2x 1.5" just to have a little room for error. I'm not sure how big your new tank is but I flow around that thru my 380G tank.

Hope this info helped and of course many people have different ways of thinking and doing thing, so this is my opinion only!

Here is a overflow calculator:
http://www.reefcentral.com/calc/drain.php