# Diffusing Co2 with a mini filter



## Another Will (12 Sep 2010)

Hi, 

I started using an Interpet Pf mini filter to 'spread' co2 around my tank. With just the co2 tube being fed into the filter, I got good misting around the tank, but the 'popping' sound as each bubble hit the impeller seems to upset the fish a bit, as they go into hiding.

I tried a cheap blue airstone on the end of the co2, and this created  a smaller stream of bubbles, with less noise (and happier fish). It also gave an incredibly fine mist throughout the tank, with bubbles that could only be seen close to the tank. The tank looks clear when sitting further away. 

Thing is, as you may have guessed, the airstone had crumbled after a couple of days, so my question is does anybody know of a small co2 diffuser I can place into my filter (max 1" diameter/square) to diffuse the co2?

I do have a glass diffuser I got from aquaessentials a while back, but thats harder to fit in the filter.


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## nry (12 Sep 2010)

If you have an external filter then the Boyu inline diffusers for Â£5 via eBay are superb.


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## squiggley (12 Sep 2010)

Somewhere I heard it suggested to use a cigarette filter (roll your own) in the end of the air line. These are quick and cheap to replace


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## stevec (12 Sep 2010)

I blocked the end of the co2 tube and peirced lots of holes in the tube with a hot needle worked for me (you need quite a large needle think i ended up with a darning needle as with a normal sewing needle the hole was too small)


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## Another Will (12 Sep 2010)

Thanks for the replies, chaps.

Really like the idea of blocking the tube and putting holes in it. I have some 0.8mm and 1mm drill bits I can use.

Cheers!


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## nry (12 Sep 2010)

You'll never get fine mist CO2 with melted holes in the tubing...find a ceramic airstone if you must, these should withstand CO2 and give small bubbles, but the inline diffusers will likely be more efficient.


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## Another Will (12 Sep 2010)

I did try an inline reactor a while back, but it reduced the flow of my filter too much (probably more to do with the design of the reactor.

The airstone I used changed the bubble of co2 to a constant flow of smaller bubbles, which I would imagine the drilled holes would emulate. I'll give it a try, and if it doesn't work, I've only lost 1cm of tube. Any pointers on a ceramic airstone, just incase?


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## nry (13 Sep 2010)

Can't recall where mine was from years back, however make sure you buy a suitable one as those designed as airstones give bubbles which are way too big and you'll end up wasting masses of CO2.


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## stevec (13 Sep 2010)

nry said:
			
		

> You'll never get fine mist CO2 with melted holes in the tubing...find a ceramic airstone if you must, these should withstand CO2 and give small bubbles, but the inline diffusers will likely be more efficient.




it will not create a mist but it does create smaller bubbles
and i debate that inline diffusers are more efficient after taking out my up diffuser to try injecting co2 into the intake of the filter i left the setting as it was came home the next day and fish were gasping and for the first time ever my drop checker manage to turn pale yellow so had to drop the co2 very quickly?
at first i had the in tank reacktor and thought i would get better results after reading about the up diffuser on these forums gotta say that 1st for me is co2 into filter, 2nd in tank reacktor, 3rd place inline up diffuser


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## nry (13 Sep 2010)

Inline diffuser should be much better than using an airstone - can't comment on inline vs any other method.


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## Garuf (13 Sep 2010)

The theory behind misting is that there is a higher level of co2 in the water without it entering the water, these bubble of pure co2 then hit the leaves and give higher levels of co2 than a water column that is devoid of bubble but has the same amount of co2 in solution. Also since they're smaller they diffuse more readily and mean that less co2 can be used to reach the same saturation in the solution, the mist that is in the solution is then additional pure co2 meaning more co2 is actually available to the plants.


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## stevec (14 Sep 2010)

well i noticed a definate drop in growth of the plants as soon as i used the up diffuser and had for the first time an algae problem the co2 into the filter has definately returned the rapid growth of plants how long the filter lasts will be the test though


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## sdlra (1 Oct 2010)

Inline Diffuser works really well.Make sure use it on outlet not intake of your Canister.


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## ghostsword (2 Oct 2010)

sdlra said:
			
		

> Inline Diffuser works really well.Make sure use it on outlet not intake of your Canister.



Why not?


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## sdlra (2 Oct 2010)

Because from experience spreads the CO2 better through the Tank,and also the Cannister has Filterd the water.If done via inlet would clog.Have the spray bar at the back of the tank with the flow hitting the front creating a better current for the co2.


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## Gfish (2 Oct 2010)

Hi all

Ive read this thread with interest. Being fairly new to CO2 I've not yet had the chance to trial the various methods mentioned here but as a starter I have placed my small sera diffuser, set on the glass right below my FX5 intake. This method obviously uses the whole filter to actively diffuse the CO2 bubbles, and it then sends them back into the tank via a full length spraybar along the back wall. I have no noticeable fog or misting as the CO2 is obviously very well dissolved. I don't know if thats the best way or not????

Would there be any advantage in me ditching the diffuser and just drilling a hole in the top of the intake pipe and poking the end of the CO2 tubing in there, to have the gas injected directly into the filter?  
I can't see that it would make much difference, apart from the fact it would be one less piece of hardware in the tank. 
Any ideas ???

I'm interested to give it a go to see if its a more economical way to inject. I think my intake being about 3 inches above the diffuser at present is probably sucking in 90-95% of the tiny bubbles the diffuser throws out. So a small amount of CO2 rises to the surface straight up and in the far corner of the tank. This is a fairly minimal amount of wasted gas, but nevertheless, it is waste.

Cheers

Gavin


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## sdlra (2 Oct 2010)

The idea of the Diffusser is to hold the CO2 and as it were mash it up thus making CO2 disperse better in the Tank.If you want to keep your Diffusser place it under the inlet inside your Tank which means the bubbles will be drawn to the intake.However me personally still advocate  an inline diffusser on the outtake.


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## Gfish (2 Oct 2010)

Did you miss what I wrote?  that's exactly where I have my diffuser, right under the intake.

The only thing about inline is that my pipes are FX5 size which is about an inch internal diameter.


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## ukco2guy (2 Oct 2010)

Hi,

I wondered about this method considering the amount of good comments about having it on the intake. For me i worry about a premature lifespan of my Eheim 2078 and i just cannot afford to replace it at present. Can anyone comment of their experiences with external co2/canister filters and if it affects the lifespan?

Cheers,


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## sdlra (2 Oct 2010)

Oops just noticed i would leave as is then.I do know Manufactures are not keen on the inlet method.I still much prefer the outtake method more.Good luck to you.Whatever works for you stick with.


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