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View Full Version : External Coast to Coast overflow....How to figure what the "tooth" will flow?

110galreef
11/29/2010, 10:35 AM
It is a 1/4" slit (pretty sure), that runs 24" in length? I have tested with like 500-700gph and seems to be about the max? 700 looks ot be pushing it. As the water level in the tank, seems to be right at the top of the tooth. But I would imagine 700gph should be handled quit well for the overflow. I don't plan more than 700gph anyway. 550gph seems about ideal for the overflow

However this should be way more available space to overflow than a std internal box that is like 16 x 6. As this only has an available 28" of area, but half is teeth? But they are taller teeth. I have pushed about 1000gph thru on before on a 110g setup w/o issues

Would making the slit like 5/16? It definitly is not backing up, just wondering if the surface skimming performance would be effected?
110galreef
11/29/2010, 09:09 PM
Any thoughts.....
das75
11/29/2010, 11:26 PM
yep, there's a Excel spreadsheet on Reefs.org in the download section called Overflow Capacity Calculator,

You put in the variables, number of teeth, width of gap etc and you can find the gph.

see here (http://www.reefs.org/library/downloads/)
mr.maroonsalty
11/30/2010, 05:16 AM
how much material is between the 1/4" slit? Lets say you have the same amount of material as the slit (1/4 1/4) that equals 12" of opening in a 24" weir the overflow calc on the home page gives you 800gph. Tooth length must be a variable; I don't know how to fit that in; my machine can't use that download from reefs.
110galreef
11/30/2010, 08:28 AM
how much material is between the 1/4" slit? Lets say you have the same amount of material as the slit (1/4 1/4) that equals 12" of opening in a 24" weir the overflow calc on the home page gives you 800gph. Tooth length must be a variable; I don't know how to fit that in; my machine can't use that download from reefs.


There is ONE tooth. It is 24" long and a 1/4 (tall)
autodave
11/30/2010, 08:44 AM
I don't run any teeth on mine-you can push alot of flow and provides great surface skimming
110galreef
11/30/2010, 08:47 AM
I don't run any teeth on mine-you can push alot of flow and provides great surface skimming


what is the size of your coast to coast and how big is the slit? also what flow are you running thru it?
das75
11/30/2010, 09:11 AM
There is ONE tooth. It is 24" long and a 1/4 (tall)

you can use the spreadsheet but one tooth, 24" wide 1/4" up is 780gph.
110galreef
11/30/2010, 09:15 AM
you can use the spreadsheet but one tooth, 24" wide 1/4" up is 780gph.

Ok, then i should easily be fine as max should be 700gph unless pump is way underated.

Do most of you find the water level in tank is at the top of the overflow slit regardless. As this was my concren? The display wasn't filling up, just wanted to be sure would still surface skimm effeciently.
110galreef
11/30/2010, 09:16 AM
das...

Thanks for the link & calculation. I don't currently have excel on this laptop. I will play later with the calculator.
autodave
11/30/2010, 09:47 AM
what is the size of your coast to coast and how big is the slit? also what flow are you running thru it?
I have an external overflowbox-not a full c2c-but my tank is 30x30 and my external is 15 inches.I am running about 1200 gph through it.I cut out my teeth and glad I did,I have had a few fish go over.With the size you have and the flow your looking for you should have no problems with that,it should be a nice thin sheet of water.