What size CO2 Reactor for my set up? - The Planted Tank Forum
  • 2 Post By NuclearArmedBarbies
  • 2 Post By Kathyy
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post #1 of 6 (permalink) Old 11-06-2015, 03:21 AM Thread Starter
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Been on the fence, but finally decided to go through with setting up pressurized co2.

So before I order, I just want to double check what size reactor I should get for my set up.

I have a heavily planted 100 gallon tank (60" long x 18" front to back x 20" high) and will be using a single SunSun HW-304B (rated 525 GPH, more likely a whole lot less flow than mentioned) canister filter in-line with the reactor. So with my tank and flow rate, what reactor housing dimensions should I be looking for?
I am currently unsure what co2 injection rate I will have.

I just want to get the right size so I won't have any undissolved bubbles being blown into the tank.

If you don't know for my set up, can you mention your tank and flow rate so I have a general idea what size may work for me.

The sizes I can get are (whole house water filter for Cerges style reactor);
20" tall x 2.5" wide
20" tall x 4" wide
24" tall x 2.5" wide

Any reason to go with Rex Griggs over Cerges? I guess it's a bit cheaper and more customizable, but I kind of do like the more "professional" look of a Cerges reactor.
If I did go for Rex Griggs style building out of PVC, what dimensions should I go with?


Looking to order today!
Just want some opinions on what size reactor housing to get for my set up.

Nobody at all?

I'm sure plenty of people are using Cerges or Rex Griggs reactors.

Even just knowing your filter flow rate and the dimension of your reactor would be very much appreciated.
As well as with you set up, if you do or don't get micro co2 bubbles making it out of the reactor undissolved and into the tank.

Last edited by Darkblade48; 11-08-2015 at 03:31 AM. Reason: Please use the edit function for back to back posts to keep threads cleaner
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post #2 of 6 (permalink) Old 11-06-2015, 09:49 PM
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While I don't have a cerges reactor myself, I do have a rex griggs reactor. From my knowledge based on the research I did, the length of the reactor is more important than the width. The longer the reactor, the more time the co2 has to disolve in the water before it is blown into the tank. Personally I'd go with the 24inch by 2.5inch filter if I were you, seeing as it'd provide the most dissolution time with impacting your flow rate the least.

My rex griggs was made out of spare piping I had. It is 2 inches wide and 11 inches long and I get a few micro-bubbles a minute.
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post #3 of 6 (permalink) Old 11-06-2015, 09:54 PM
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I have a 4"x20" whole house filter housing and it works really well on my 180 gallon tank. I don't know if width matters or not. I used the outside of the inner ring to fit my PVC pipe so inner and outer circles have closer to the same size areas in cross section as one wants to keep the bubbles tumbling in the outer ring until dissolved and I didn't want a sudden increase in velocity pulling them through into the tank itself.
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post #4 of 6 (permalink) Old 11-06-2015, 11:37 PM
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I use this one - works perfectly with a fluval 406, bubbles never reach the bottom.

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post #5 of 6 (permalink) Old 11-09-2015, 09:02 PM Thread Starter
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Thanks everyone for the replies.

I'm just about to order, but forgot to ask about the size of the ports (the threaded insert connections for inlet and outlet).
Which size ports should I get?

My SunSun 304B uses 3/4" inner diameter - 1" outer diameter tubing, but the tubing leads to skinnier 5/8" ID, 3/4" OD black tubing.

I've seen the whole house filters come with 3/4" or 1" NPT brass ports, which should I get? Would either work? I want to keep as much flow from my canisters as possible (if flow proves to fast, I can install a ball valve, but I don't want the "unadjustable" fittings slowing down the flow, yes I am aware in-line devices reduce flow).
Would the 1" provide any benefits or does it only end up being a little costlier for the larger 1" fittings when assembling the reactor?

And by the way, is the filter wrench really needed?
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post #6 of 6 (permalink) Old 11-10-2015, 03:12 AM
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The filter wrench is needed for opening the filter housing when the servicing of the filter element is needed. As you are using the unit without a filter element - no element requires service and you don't need the wrench to open the housing for any purpose other than cleaning which may become essential only after ten years or more if at all.

If the output tubing of your filter has ID of 3/4" then the input side of your whole-house filter will need to be fitted with a 3/4" nipple; if otherwise it is 5/8" then the nipple needs to be 5/8". Use only a single piece of tubing from the filter output to the cerges reactor. I would like you to use the 20" tall x 4" wide choice for the cerges.

If the lead tubing to your tank's return from the filter is 5/8" then the output side of the cerges should be fitted with a 5/8" nipple and a single tubing used.

If you have a choice, you have a problem, till you elect your choice. No choice, no problem, only consequences, learn to live with them.
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