View Full Version : how to calculate drainage for notch..
nanopodreefer
12-04-2006, 07:43 PM
Can anyone tell me how to calculate the max volume of water that will flow through a notch in the top of my tank that is 1.5" ht x 8" lgth, and what is the formula. I looked at the calculators at reef central but they didn't seem to work, thanks. :smile:
Pescador
12-04-2006, 08:03 PM
I was playing around with the RC calculator and got this
Gallons per Hour = 800
Recommended minimum drain pipe diameter = 1.17 inches
Recommended minimum linear overflow size = 12 inches
I don't know if that would apply to yours for sure.
Wouldn't it depend more on what size of pipe you have attached to the overflow for the drain?
Bazins formula is what you are looking Q = 0.66 x cB x (2g)0.66 x H1.5
http://www.aquatext.com/calcs/weir%20flow.htm
And from sprdsht I got for flow/height for a slotted weir. Works out for 1.5" over a single 8" wide slot 3820gph
Funky_Fish14
12-05-2006, 12:03 AM
You must remember to leave some leeway, as that formula is designed for large applications, such as in rivers, etc... In a smaller system, the water will be much more compressed into the small slot while wrapping around the corners of the space, this causes more of a problem with 8" than 50ft. Also, I would definetly shorten B as suggested on the page.
Thanks for the link on that formula, Mark!
Chris
Pescador
12-05-2006, 12:19 AM
Great reference, Thanks Mark
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