# CO2 reactor vs CO2 in filter intake



## iris600 (Feb 12, 2004)

I know some canister filters have problems when CO2 is put into the intake. This said, I have a 20 high that I am doing, I decided to go with pressurized CO2 (jbj reg), and will have a canister filter. Looking at this, I am wondering if there are particular brands or types of canister filters that don't seem to have problems with CO2 going into the intake, and brands that seems to continually choke up with CO2. 
I have no problems with reactors, but I want to make sure it is external. I really don't want to have a pump and a filter on a 20, so is there a way to hook up an external reactor to the filter output line?
Comments? Brands of reactors or DIY reactors used on filter output lines? Particular flow rate needed to have a reactor work on filter outtake? Don't want to create too much current.


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## Rob G (Oct 19, 2004)

I have a 20 gallon high setup that may be similar to your preference. I use compressed CO2, which is fed into an external reactor that is plumbed into the outflow of a Fluval 204. The return from the reactor feeds a submersed spray bar, which is throttled down by a ball valve. I find that that the 204 provides a nice amount of flow for this size tank. On a side note, when I plumbed in the reactor, I replaced both the input and output hoses with smooth-walled tubing. I didn't much care for the tubing that came with the filter.

FYI, prior to switching to compressed gas, I fed DIY CO2 into the intake of the same cannister filter with success. It was, however, noisy at times, and it was not 100% efficient (i.e. every once in a while I would hear a whoosh, and CO2 would be expelled into the tank in the form of many not-so-fine bubbles.


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## ORION (Jan 19, 2005)

Using a canister as a reactor can reduce efficent of biological filter. I know that the activity of nitrification changes due to pH. So if you give co2 in it, nitrification activity can reduce because of low pH due to high co2 concentration in canister. You can find post about extarnal reactors in DIY section.
And glance at http://www.gwapa.org/articles/inlineco2reactor.asp


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## inkslinger (Jan 1, 2005)

any canster filter that has a motor at the bottom is ok , i use a magum 350 which is perfect for it , it will not air lock on you at all . you can also bulit a external co2 reactor , i just bulit one myself , i use a local plastic supplyer on the yellow pages and found one that sold me a foot of polycarbonate tube [clear tube like clear pvc but much stronger ] it cost me $9.50 plus tax, 2in by 12in , then 2 - 2in 3/4 reduce bushing with 2- 90' elbows 3/4 to 5/8, i also drill and tap treaded a 1/4 to 1/8 brass hose barr for the co2 i use small bio balls or you can fit 10 of the large bio ball if you like, put the balls in glue the bushing on the end i use a little pvc cement on the pvc bushing and bought weld-on 16 for the clear tubeing , than use some taphlon tape on the the elbows and the brass barr when you hook it up to a canster filter go in at the top an come out at the bottom put the co2 inlet at the bottom part that way it goes up the curtent better and you can also use clear pvc tubing a if does matter use normal pvc to and if you need to use 1/2in tubeing change the elbows 3/4 to 1/2


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