DIY overflow attachment - flow rates?

[Richies^Ghost]

Hello peoples,

So I've made a vertical style overflow (takes water from the surface) but I am also making a horizontal style (takes water from below the waterline) so that detritus is collected.

Instead of having it go straight into the tank and collecting detritus from one spot, I'm making it go down then branch out using smaller diameter pipes. These pipes will be capped, with holes drilled in them.

So my question is one of flow rates...

1) The main pipe is 25mm - how many 20mm branches would take advantage of the 25mm flow rate? From the pipe sizing sticky, it appears as if two 3/4 inch pipes would go into a single one inch pipe - my guess is that two is the right answer for my question.

2) What diameter holes should be drilled, and how many, to maintain a strong suction whilst ensuring maximum flow? The two(?) pipes will be different lengths - the one going across the back of the tank will be twice as long as the one going to the front of the tank.

Any ideas are appreciated

 

[fallin49er]

a drawing of what you are trying to do would help get you more answers.

 

[CHOMPERS]

You have to use the cross sectional area of the pipe in your calculations instead of the pipe diameter. The formula for area is
A = pi x r^2

or

A = (pi x D^2) / 4

And the total area of your holes needs to be equal to or exceed the area of your pipe.


...notice I said "your calculations" and not mine.