diy overflow question

[wakeboard3584]

i'm building a toothless internal overflow box for my 40 gallon breeder. my pump will be pushing just over 500 gph and i'm wondering how far above the overflow box the water level will sit. my calculations give me around 1/8". is this correct?

 

[wakeboard3584]

whoops, might help if i told you that the top edge of my overflow box is 12"

 

[salty blues]

Originally Posted by wakeboard3584
http:///forum/post/3056963
i'm building a toothless internal overflow box for my 40 gallon breeder. my pump will be pushing just over 500 gph and i'm wondering how far above the overflow box the water level will sit. my calculations give me around 1/8". is this correct?
Yeh, I would guesstimate somewhere between 1/8" to 1/4" would be correct. I run a 500 gph setup on my 29g with a toothed o/f and that's about the rise I get.

 

[wakeboard3584]

Originally Posted by salty blues
http:///forum/post/3057881
Yeh, I would guesstimate somewhere between 1/8" to 1/4" would be correct. I run a 500 gph setup on my 29g with a toothed o/f and that's about the rise I get.
what are the dimensions of the overflow? i'm thinkin if it were the same size overflow, a toothed type would have a higher rise in water level than the toothless, since the water has about half the area to run through. does that sound right?

 

[salty blues]

Originally Posted by wakeboard3584
http:///forum/post/3058949
what are the dimensions of the overflow? i'm thinkin if it were the same size overflow, a toothed type would have a higher rise in water level than the toothless, since the water has about half the area to run through. does that sound right?
My o/f box measures 5" X 5" X 2", with a 1" bushing and drain pipe. The bottom of the teeth opening sit a good 1/4" below the water line. I was worried when I first installed the o/f box that the water level line would be too low, but it levels perfectly just above the bottom edge of the top frame.

 

[i<3reefs]

same same

 

[wakeboard3584]

i'm hoping it doesn't rise more than 1/4" because that will put just barely below the rim. but there again, i would think my water level will only rise 1/8" because the water has no teeth to go through. without teeth, the whole edge of the overflow is passing water instead of just half or so.
on a side note, any bets on how long it will take my clownfish that sleeps at the top rim of the tank to figure out he needs to sleep at the bottom to stay out of the overflow? hahaha silly clowns

 

[salty blues]

Originally Posted by wakeboard3584
http:///forum/post/3059163
i'm hoping it doesn't rise more than 1/4" because that will put just barely below the rim. but there again, i would think my water level will only rise 1/8" because the water has no teeth to go through. without teeth, the whole edge of the overflow is passing water instead of just half or so.
on a side note, any bets on how long it will take my clownfish that sleeps at the top rim of the tank to figure out he needs to sleep at the bottom to stay out of the overflow? hahaha silly clowns
I get what you are saying about the teeth(or no teeth), but the rate at which your return pump is delivering water to the tank is obviously going to be a factor also. The only way to know for sure how the o/f will perform is to put it in use.
My clown likes to sleep between the top end of the o/f box and the side glass. So far he has managed to stay out of the box.

 

[wakeboard3584]

ok, heres my logic.
a 1 inch drain pipe can handle 600 gph. a 1" circle has an area of .78 square inches.
my overflow is 12" long. so, if 600 gph were being pushed through the overflow, the water would only have to rise .065 inches before it were taking up the same amount of flow area as the drain pipe.
12(length of overflow in inches) * X(height of water over overflow in inches) = .78(square inches needed to pass 600 gph)
X = .065 inches
i'm figuring 1/8" to be safe. correct or is my logic jacked?

 

[wakeboard3584]

anyone? any math/physics wiz kids out there?