CO2 injection into filter - The Planted Tank Forum
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 02-21-2015, 01:51 AM Thread Starter
Algae Grower
PTrader: (0/0%)
Join Date: Jan 2009
Location: Hartford, Ct
Posts: 5
CO2 injection into filter

After being frustrated of seeing bubbles from my CO2 diffusers go to the surface I decided to re-locate the diffuser to under the filter intake. I have a Eheim Eco Pro under the tank so I figured it would not have any problems dealing with the small bubbles from the diffuser. Despite having it quite near the intake I still lost bubbles so I then drilled a Medicine measuring cup and mounted that on the screen and after that I got 100 % capture and no bubbles are exiting the filter outlet. The pH in the tank is about 6.7-6.8 at a KH of 3-4 so 15-20 ppm and when I let the outlet of the filter hit the sensor on the pH meter it reads 6.5 so I have about 30ppm of CO2 in the filter so I don't think there can be any adverse effects on the bio filter or the pump. It seems like a more reliable solution than putting an external diffuser inline with the filter. Any thoughts?


tribologist is offline  
Sponsored Links
post #2 of 6 (permalink) Old 02-21-2015, 02:00 AM
Planted Tank Enthusiast
dcutl002's Avatar
PTrader: (1/100%)
Join Date: Apr 2014
Location: Smithfield, Va.
Posts: 687
Love it! If you get tired of cleaning that diffuser you may consider a DIY CERGES reactor. They are very efficient.
dcutl002 is offline  
post #3 of 6 (permalink) Old 02-22-2015, 08:16 PM
Algae Grower
PTrader: (0/0%)
Join Date: Aug 2014
Location: Austria
Posts: 13
but with this setup it would be possible that co2 or bottlegas will be left in the filter and cause a gas bubble which could damage the filter wouldn't it?
NatroN is offline  
post #4 of 6 (permalink) Old 02-22-2015, 11:07 PM
Planted Tanker
burr740's Avatar
PTrader: (130/100%)
Join Date: Feb 2014
Location: Bama
Posts: 5,848
Neat trick OP ^^

Originally Posted by NatroN View Post
but with this setup it would be possible that co2 or bottlegas will be left in the filter and cause a gas bubble which could damage the filter wouldn't it?
Depends, some brands handle this better than others. Usually if there's any build up the filter will begin to "burp" intermittently. It is not something that will go unnoticed.

I have an older Fluval 304 that wont handle even a little bit of co2 w/o burping. Havent tried it with my SunSun. From seeing other people do it, most Eheims seem to be OK with it. Although I dont own one so cant say for sure.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

burr740 is online now  
post #5 of 6 (permalink) Old 02-23-2015, 12:00 AM
Planted Member
PTrader: (5/100%)
Join Date: Nov 2010
Location: Portland, Me.
Posts: 255
I thought I read on here that putting the CO2 directly into your filter intake creates conditions in your filter that are too acidic for denitrifying bacteria?
Sluggo is offline  
post #6 of 6 (permalink) Old 02-23-2015, 02:10 AM Thread Starter
Algae Grower
PTrader: (0/0%)
Join Date: Jan 2009
Location: Hartford, Ct
Posts: 5
Thank you for the input!

I seen claims for both it being harmful for the bio filter and for the pump impeller but I did not see any first hand information on this.

Since the condition (pH) of the water leaving the filter indicate about 30ppm and the fact that the bubbles seems to absorb fairly well I'm not that worried that it would be harming the bacteria. The condition in the filter should be the same as if I have 30 ppm in the tank, right?

In regards to cavitation damage I think there is some confusion on that. Cavitation damage or erosion occurs when the pressure is the liquid is so low that you for a vapor bubble that then collapses at or near the surface resulting in very high pressure spike that is deforming the metal. You can also get cavitation driven corrosion on materials like stainless that is protected by oxide layers. To collapse a CO2 bubble would require you to dissolve it and that is not as fast of a process as collapsing a steam bubble that is condensing into liquid so I don't think it is likely to happen.

I have however noticed that I do get burping now and then when I am increasing the flow rate of the CO2 trying to get 25-30ppm in the tank so I will probably pick up a 10" filter housing and make a in-line reactor.

I did order a Sera Flore CO2 Active Reactor 500 a few weeks ago from Petco but after 10 days seeing it show as "In progress" and twice calling just to talk with some clueless customer service people I cancelled the order and will go with a DIY reactor instead.

tribologist is offline  


Quick Reply

Register Now

In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome