# CO2 Line Splitting and Even Distribution



## Annextro (Nov 7, 2016)

Hopefully someone here will be able to help me work out this problem I'm having!

The problem revolves around splitting a single CO2 line to 2 separate lines feeding 2 identical diffusers in the same tank. I've got the main line from the bubble counter (on the regulator) running to a splitter where it diverts the gas to 2 separate (same size and length) air lines. I've tried several different "splitters" with no luck; granted, they are plastic ones bought for under 5 bucks. The one I'm currently fiddling with has 2 inputs for gas lines (one can be closed) and 2 outputs with twist-knobs designed to control the output flow rate. One line runs to an in-tank diffuser (Rhinox 2000) going directly in to the water column, and the other line runs to an identical diffuser placed underneath the intake of my canister filter. Both of the output lines have bubble counters on them, so I have verified that they are each working and can distribute gas to each diffuser independently. I can't seem to get even distribution of the gas across the two diffusers; it seems like the gas is always choosing the path of least resistance (as it should...?) and not distributing evenly across the lines. With this splitter I have tried closing one input and only supplying gas through the other, and I have also tried supplying gas to BOTH inputs. Neither seem to really work. I have also tried another plastic splitter with only 1 input and 2 outputs, and that didn't work for me either. I have had temporary success with having both bubble counters active, just at different rates. Come the next day, only one counter is bubbling and the other is inactive. Hence this is the crux of my issue.

I know there are many people out there running the same setup, or who have 1 CO2 tank supplying gas to several different aquariums, so there must be something I am doing wrong! Any insight would be greatly appreciated!!!


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## 2wheelsx2 (Apr 21, 2010)

Your problem is the splitter. You need a manifold to split the lines and then a needle valve for each diffuser. I use brass ones but Pat (Mykiss) at Canadian Aquatics sells some plastic ones. I have never tried plastic ones so I don't know how well they work.

CANADIAN AQUATICS


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## kivyee (Oct 15, 2016)

You basically have to be able to adjust each line so that the pressure drop is the same, otherwise your flow will be uneven. Your two diffusers are also at different heights so the pressure on each will be different. 2wheelsx2's method will work - the needle valve is key.


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## Bien Lim (Apr 21, 2010)

I tried those plastic splitter and they don’t work very well. You need a manifold, Mykiss and king ed are the only local that I know off that carries them.


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## Annextro (Nov 7, 2016)

2wheelsx2 said:


> Your problem is the splitter. You need a manifold to split the lines and then a needle valve for each diffuser. I use brass ones but Pat (Mykiss) at Canadian Aquatics sells some plastic ones. I have never tried plastic ones so I don't know how well they work.
> 
> CANADIAN AQUATICS





kivyee said:


> You basically have to be able to adjust each line so that the pressure drop is the same, otherwise your flow will be uneven. Your two diffusers are also at different heights so the pressure on each will be different. 2wheelsx2's method will work - the needle valve is key.





Bien Lim said:


> I tried those plastic splitter and they don't work very well. You need a manifold, Mykiss and king ed are the only local that I know off that carries them.


Thank you all for your replies! They make total sense. I've had great experiences with Canadian Aquatics in the past, so I will check it out.


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