How can suck air into my return lines?

[MimicTang]

I wanna use some physics to suck air into my return lines on the way to my growout tanks by creating suction as the water passes by. hence not needing any air pumps.

[mr pink floyd]

not sure if this will work, but if you bring the pipe up maybe a foot over the tank, put a T on vertically, so the water goes straight down, put a cap on the top side of the T with a hole drilled in it, i think the water would create suction as it tries to start a siphon, and air will be drawn in through the hole...

to get the air to mix with water better, try fitting the hole with airline and running it down

im not entirely sure this will work, but when i think of it in my head it sounds plausible..

[Pbrown3701]

you wont pull much air that way. You would be better off to add a venturi to the line, and then it would suck air - but only if you have a big enough pressure drop across the venturi.

This will of course limit your flow if just gravity fed.

[mr pink floyd]

how exactly does a venturi work anyway?

tell me if im wrong, but is it just water rushing past a hole causes an area of low pressure that the air fills?

[BeanAnimal]

That is the basic idea yes... the effect is more pronounced if you force the water to try and compress by shoving it into a narrow space that opens into a larger space... because water is not compressable, there is a large pressure change at the narrow point and then at the wide point. The pressure change is what creates the suction.

Anyway you can look up the bernoulli principle and find more than you ever wanted to know.

[MimicTang]

Ok so how can I setup some piping to acheive this.

[RandyStacyE]

First of all what size is your return plumbing and is it PVC?

[MimicTang]

it doesnt exsist yet. probably 1" hdpe