Overflow box design clairification help

[jays900]

I would like some clairity. After reading many threads on this topic, I seem not to have a clear answer and I'm begging for clairity.

I have a 60 gallon custom tank build project. I have the tank drilled with a 1-1/4" bulkhead for the drain. I will be running a Mag 12 pump. After head loss I should be around 700 GPH flow rate. I chose a 1-1/4" so I could regulate flow if necessary.

Now here is the question:

I have an acrylic overflow box which I need to cut the notches into. The box measures 7" ID wide by 4-1/2" ID deep. For a total linear overflow of 16" minus 1" on each side for the returns lines which makes it 14" net. I've come to the conclusion that the notches should be a 1/4" wide and about a 1/4" on center. How long should the notches be? I'm thinking 1" long to 1-1/4" long.

Any assistance would be most greatly appreciated.

Thank you!

 

[john_blaze]

I am by no means an expert, but I have been doing a TON of research for my own overflow box. From what I have gathered, teeth are really only needed to keep things OUT of the overflow so I do not think that their length plays a significant role. If you want, check out this thread:

http://www.reefcentral.com/forums/showthread.php?t=473152&highlight=calfo+overflow

You have to read through it a bit, but there are tons of Q&A's on overflow concepts/designs.

IF you make your overflow long enough and push enough GPH you can make the sheet of water over the overflow thin enough to keep pretty much everything out. 90 deg elbows turned down are an added security measure (Beans suggestion from the thread)

HTH :beer:

 

[jays900]

Thank for you reply. I've read that thread up and down already. The only thing I gathered was the same thing you mentioned which was the the teeth is to keep things out. The other was that the teeth should be about 1-1/2" long. I figure that if I go about 1-1/4" I can always make them bigger later if necessary.

The next thing I'm going to research is maybe going toothless. My overflow box is 1/4" from the top of the tank. If I need to cut some more I still have time. Thanks again for the reply.

:beer:

 

[LifeAquatic]

The teeth will also limit the water volume pushing into your over flow box. I would go about 1 1/2. It will be a pain to cut them later once everything is hooked up.

 

[jays900]

Thanks! I think I'm leaning towards a toothless overflow. From what I've been able to find, it's quieter & has less maintance. Now my decision is how much off the top of the tank should I be?

I was able to find a thread, by accident, on the tooth length recommendation.

Here it is: http://www.reefcentral.com/forums/showthread.php?t=1726293&highlight=overflow+height