# co2 and hang on back filter



## dpeipus (Feb 5, 2010)

Is it even worth the trouble to use co2 system with a hang on back filter?


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## Darkblade48 (Jan 4, 2008)

You can still use CO2, yes. 

Just increase the water level a little so that surface agitation from the filter return is minimized.


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## Lab_Man (Dec 7, 2012)

I use a HOB and like the flow that I get from it. I can keep my CO2 in the 30 ppm range at a 1.5 bpm rate with a GLA 75 mm Atomic diffuser. 

I have to supplement O2 so the fish don't start gasping for air.


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## tattooedfool83 (Mar 15, 2013)

Are u guys feeding the co2 intake line into the intake of the hob?


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## Entomologist210 (Nov 16, 2013)

I am, but I'm still unsure if it's a good way to get more CO2 from my DIY yeast system into the tank or if I'm just making it easier for the CO2 to exit the tank through agitation.


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## Lab_Man (Dec 7, 2012)

tattooedfool83 said:


> Are u guys feeding the co2 intake line into the intake of the hob?



I am injecting CO2 on the opposite side of the aquarium from the HOB. I have a circulating fan to propel the CO2 bubbles down and across the aquarium. The bubbles then are propelled by the HOB flow across the aquarium and down the glass wall. Then due to the current, the CO2 makes several revolutions around the aquarium and is disbursed through the water column.


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## Lab_Man (Dec 7, 2012)

I don't inject into the HOB filter intake because I think that I'd lose more CO2 due to surface agitation. Cavitation (due to the CO2 bubbles) of the pump is also a concern as it would cause a pre-mature failure of the pump.


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## tattooedfool83 (Mar 15, 2013)

I have a co2 tank half full and a 20 long with 2 Hobs on it. Debating how to go about injecting co2. I have it on another tank and was using a power head to distribute the co2.


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## Lab_Man (Dec 7, 2012)

The biggest factor that contributes to CO2 loss because of HOB filters is low water level. If you are vigilant and keep the water level up the HOB doesn't effect CO2 too greatly.


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## shift (Jan 7, 2013)

Cooler water also holds more co2. On the flip side you want some surface agitation or an air stone so you don't has your fish (if you are injecting high amounts)


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## Lab_Man (Dec 7, 2012)

shift said:


> Cooler water also holds more co2. On the flip side you want some surface agitation or an air stone so you don't has your fish (if you are injecting high amounts)


I found that I had to add an air stone when I transferred my fish into my planted tank. They were gulping and breathing heavily at first without the air stone. After adding the air stone everyone is happy, happy, happy.


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