# Inline diffuser on the inlet to or outlet from filter?



## Whitebeam (13 Sep 2010)

Simple question, but conflicting indications of the correct answer: Into which hose of the filter should the inline diffuser be inserted? Input or output? I notice that the Boyu is designed to replace the inlet strainer, suggesting the answer is 'inlet', with the filter acting as a reactor; but most of the posts I read have it on the output, so I guess the answer should be 'output'.

Peter


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## Dolly Sprint 16v (13 Sep 2010)

Hi 

Always put the inline diffuser on the out going water form the filter unit - if you place it on the incoming water pipe the ceramic plate or tube (in this case) will get clogged up as the filter unit is pulling all the dirt / debris from within the water column.

Regards
paul.


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## sdlra (1 Oct 2010)

I suggest the outward side of your Filter.Not only will you have the diffusser being clogged up onthe intakebut also could create airlock.


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## Themuleous (3 Oct 2010)

Outlet, every time 

Sam


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## CeeJay (4 Oct 2010)

Hi all
I would recommend the outlet too.
Some have used them on the inlet, but the CO2 will also attack the seals/O rings on your filter and you could end up with a living room full of water   .
I haven't seen anyone report on here that their seals have failed, but they will eventually.
It's for this very reason that you cannot use 'standard' air line for CO2 delivery. It will eventually perish and you will lose all your gas.


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## steveninaster (19 Oct 2010)

I would've thought the CO2 bubbles would dissolve or be moving about within the water and have very little contact with seals\o rings, unlike the airline which is in permanent contact.  I bubble my CO2 into the inlet and from what I can tell the any bubbles get trapped in the sponges and dissolve there.  So I guess I may have to replace sponges more often.


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## George Farmer (19 Oct 2010)

Whitebeam said:
			
		

> Simple question, but conflicting indications of the correct answer: Into which hose of the filter should the inline diffuser be inserted? Input or output? I notice that the Boyu is designed to replace the inlet strainer, suggesting the answer is 'inlet', with the filter acting as a reactor; but most of the posts I read have it on the output, so I guess the answer should be 'output'.
> 
> Peter


Good question! 

Most inline diffusers are designed to be place on the outlet, so the CO2 microbubbles or mist can be distributed effectively throughout the water column.  CO2 like this, in its gas form, is more efficient at delivering CO2 to the plants.  It also means that one can run a comparatively lower dissolved CO2 level in the aquarium, yet still obtain enough CO2 for the plants.

However, this method does require excellent water circulation in the aquarium to enable the CO2 mist to reach _all_ parts of the tank and plants.  In poor circulated tanks some plants will be getting plenty of CO2, others will starve and algae will proliferate.

I have noticed that in tanks with lower levels of circulation it's better to have the CO2 100% dissolved.  It seems that the CO2 is more easily distributed this way, and all the plants stand a better chance of getting their required CO2.  

This assumption is based on experience with various set-ups and differing CO2 delivery methods, from ladder diffusers, to ceramic discs placed at the opposite end to the filter, to inline diffusers place on the inlet and outlet.

For me the hobby is more about aesthetics than pure plant growth and gardening.  So I have an inline diffuser placed on the inlet.  This means I don't get millions of white bubbles all over, spoiling the aquascape.  The trade-off of this vs. risk of the filter leaking (I haven't had an issue in over 7 years of CO2 being pumped directly into filters in one way or another) and better plant growth is worth it, in my experience.

So, in summary; if you want the best possible plant growth and have excellent water circulation, and don't mind seeing lots of bubbles floating about, then positioning your inline diffuser on the outlet is the better option.

If you want 100% CO2 diffusion and no bubbles then the inlet is an option.


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## andyh (19 Oct 2010)

I have recently moved my UP inline Atomizer from my outlet to my inlet under advice from Mr Farmer.

Why?
I had become frustrated with the misting. I wanted the tank to look crystal clear. Also i had never been able to get my drop checkers to turn go greeny/yellow no matter the bubble rate.

When?
I moved it over onto the inlet approx. 10 days ago and the results have been great. The is no mist whatsoever in the tank, my water is crystal clear. Secondly and most interesting my CO2 drop checker turned yellow for the first time. No adjustments were made and my co2 drop checker turned yellow after about 3-4hrs. This had never happened before so it suggest that the co2 is being diffused better, i suspect the impeller on my filter has something to do with this.

nb. the filter this is connected to is my second external on my tank and only contains coarse filter pad, filter wool and active carbon.


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## Dolly Sprint 16v (19 Oct 2010)

Andyh

The media within the filter has a significant affect on breakdown the co2 bubbles - same affect as the bio balls within an AM1000 reactor.

Regards
Paul.


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