# [Wet Thumb Forum]-External CO2 Reactor Config Help (outflow)



## Detox (Feb 26, 2004)

Which Setup (see attached image) is best when configuring your CO2 reactor on the outflow (inline) of your canister filter?

Cheers,

Detox


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## Detox (Feb 26, 2004)

Which Setup (see attached image) is best when configuring your CO2 reactor on the outflow (inline) of your canister filter?

Cheers,

Detox


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## docjosh (May 12, 2004)

I have mine set up as number 1. It allows the CO2 gas to go to the top and dissolve as water flows through it. I would think Setup #2 would push the CO2 gas (undisolved) into the tank. As a side note: my CO2 line enters the top of the reactor but then the tube extends to the bottom and the bubble move back up to the top (might make it easier to connect the CO2 in line without water pouring out the reactor?)


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## Hawkeye (Aug 20, 2004)

docjosh is right on. The correct way to set up a external CO2 reactor in setup #1

Hawk


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## Detox (Feb 26, 2004)

I appreciate the replies. 

I am going to hook up the CO2 reactor as per Setup #1. However, as a small modification to Setup #1 the Co2 inpue line will run at the top of the reactor parallel to the water flow. I already have this drilled and don't want to change it. 

I figure the Co2 entering from the top would be better because CO2 gas will enter the reactor and meet the water flow and bioballs. If the CO2 enters from the bottom there is a chance that a lot of the CO2 will pushed to the tank before it gets a chance to the top of the reactor.

What do you think?

Cheers,

Detox


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## Rex Grigg (Jan 22, 2004)

I would recommend having the CO2 injected into the reactor between 1/3 to 1/2 way down the reactor. Of course this depends on the diameter and length of the reactor and the water flow. Also if the reactor is of sufficient size you won't need the bio-balls.


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## Detox (Feb 26, 2004)

Rex,

I should have taken the advice you gave others earlier about reactor placement. Originally I had my CO2 reactor inline on the intake but I notice a lot of air was getting trapped and burped out of my Eheim 2215. Also due to a reduction in flow on the intake my filter was less efficient sucking out particles from the water. 

I did a major overhaul this evening, by placing the CO2 reactor inlineon the output. Unfortunately the reactor was already built so I kept the CO2 intake where it was. I am following setup #1 with the CO2 intake directly on the top, doesn't seem to be any problems. The chance of CO2 moving back against the flow of water and into the canister filter is slim to nil. 

Also, I replaced the Eheim hosing with braided tubing. This stuff is fantastic as it keeps the pressure and doesn't kink. 

Also, contrary to many posts, I have not lost much reduction in flow on my Eheim 2215. Now if only I could get my water a little more clear, it always seems like there is foggy haze of particles in the tank. 

Cheers,

Detox


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## docjosh (May 12, 2004)

Detox,
If you could modify a little tube to carry the CO2 inside the reactor down towards the bottom you will get the same affect Rex is talking about. Maybe a little nib to plug your CO2 line into the reactor where you drilled the hole...with the same nib on the inside and another bit of line to carry down maybe 3/4 of the reactor. I would not have regrets about where you drilled the hole...i think this will work great for you.
~Josh


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## Sigmatron (Oct 15, 2004)

Hi, I'm new . I like to know how much C02 is need , say per 100litre aquarium . Can this be monitored - low cost way ? 
Thanks.


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## imported_BSS (Apr 14, 2004)

You want to get your CO2 in the 15-30 ppm range. The most effective and low cost way to measure it is by getting a KH and a PH kit for your tank. There are lots and lots of KH/PH tables out there where you can determine the CO2 level.


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## imported_timlawyer (Jul 14, 2003)

What's the optimal degree for the bend in the tubing leading into and out of the reactor?


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## Detox (Feb 26, 2004)

If you know something in your tank is having a small affect on your kH and pH how can you measure the CO2 concentration? Currently I use a bubble counter because I cannot rely on the pH kH values.

I am assuming the kH, pH charts are void if something in your tank is affecting these parameters.

Cheers,

Detox


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## imported_BSS (Apr 14, 2004)

I guess it depends on what is causing the effect. Are you talking about buffers you've added? If so, I can't offer much. If you are talking about driftwood or such "eating" your KH (which I've been battling) or adding baking soda to raise your KH, then the chart should still hold, you just need to keep looking in a different column as your KH changes.

As to the bubble rate, certainly once you've determined that a certain bubble rate gets you in a certain ppm range that you should stay close to that assuming that you haven't changed anything. But, I'm not aware of any method for saying that X bubble rate produces Y ppm of CO2.

Then again, I'm still learning this stuff. So please offer up any corrections!


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## Detox (Feb 26, 2004)

BSS, 

My kH appears to be slightly affected by sone black lace rock in my aquarium. I did some tests and this stone does raise my kH a little. 

Tap water is around kH= 4 and with the stone I am at about kH = 9. I do not add an intentional buffers. 

Knowing that the lace rock can affect my pH and kH, is it still reasonable to use the the new values when interpreting the CO2 chart? 

I am fully aware that you can not use a bubble rate to determine CO2, there are too many factors such as size of bubble and diffusion efficiency etc. 

Cheers,

Detox


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## imported_BSS (Apr 14, 2004)

That is certainly my understanding, yes! With the driftwood I had steadily dropping my KH between water changes, I would always find that the PH dropped to whatever level on the chart correlated with a fairly consistent CO2 level.


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## docjosh (May 12, 2004)

Detox,
The issue is the difference between changing KH or adding a buffer and changing your "measured" KH. There are some great threads in this forum to help explain this in more detail (also check Roger Millers posts since he has really done a great job explaining it).
In short it sounds like you are actually changing KH so you should use your new KH value to determine CO2 concentrations.


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