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CO2 reactor excess gas

6K views 19 replies 11 participants last post by  Killavolt 
#1 ·
Planning to build a CO2 reactor... what happens with gas accumulated inside the reactor? or how do you avoid the bubble?
If Co2 dos not dissolve fast enough gas bubble will build up inside the reactor and as that CO2 comes with 15-20 psi it can
a-push water back to filter and make the impeller overwork breaking the electric motor at the end
b- push water through any joint making it leak
c- send water + Co2 undissolved through the pipes and to the tank making the tank look the same as using a diffuser ( soda sprite look)
 
#3 ·
I find that I need to bleed off the excess CO2. If I don't, it the CO2 doesn't seem to dissolve into the water as efficiently. I just pull the tube off on the reactor side of the check valve to let it bleed off.

I've thought about make mine own reactor and using a bleed valve on top. I used to ride dirt motorcycles and we had bleed valves on top of the forks to bleed off air with a push of a button. The threads are awfully small, so I'm not sure I could thread it to a DIY reactor.
 
#4 ·
But if you bleed the accumulation then your are wasting CO2 which is something I dont want to do. On the other side plantsrockmysocks said to adjust this but will this be fast enough to provide for the plants
Co2 does not easily dissolve in water.
 
#5 · (Edited)
if you have a rex reactor and sump you can tap a hole at the top of the reactor and shove a tube in it and run the other end into the sump.

edit: if you dont have a sump, you can tap a hole at the top of the reactor and attach the other end to something like a maxi-jet
 
#8 ·
This is not true
A: Simply not true for this type motor. It is not a solid connection and they are not broken even when the impeller is totally broken. It happens pretty often and it doesn't break the motor. When the impeller gets dirty, it stops moving until we clean it and then it runs without any damage.
B: Does not happen. The filter tubing is open at both ends and there is no way to build up extra pressure from a bubble collecting.
C: If this happens it is due to the reactor not being designed and built correctly. Sized and designed right , there will be no buildup and no bubbles seen in the tank. Too many people try to "improve" the original design and mess it up.

To build it right, I suggest using the original design that Rex Grigg's worked out. Do not try to improve it. Size it to fit the tank and CO2 supplied and there is no problem. Do not use a fitting to inject the CO2 at the side of the reactor. It works better when the CO2 is injected into the center of the water flow where it is moving faster. When it enters at the side of the reactor the flow is slower and the CO2 can move up the side to form the bubble. The bubble doesn't damage anything but it can cause noise from the splashing it can cause.
 
#9 ·
Hey Rich I was asking because seeing videos of some reactor they build up some giant bubble on the top. reagrding your answers
A: I got. you are rigth they are magnetic and are not really attached to any thing
B: So if there is no extra pressure (and I understand that) its is dissolved only based on time of contact with water? why people keep saying that you have to build enough pressure to disolve Co2.( not in this thread)
C:Yeah I would like to build that design without change or complications but the pictures there are gone
Finally do youcurrently have one in use? how noisy and effective is at disolving CO2
Thanks
 
#11 ·
C:Yeah I would like to build that design without change or complications but the pictures there are gone
Finally do youcurrently have one in use? how noisy and effective is at disolving CO2
Thanks
All 2" fittings cept the barbs which are 3/4". the 1/4" Co2 tubing was pulled through a 7/32" hole.
Materials list:
2" PVC pipe
2" PVC Coupler
2" PVC Tee
2" PVC plug
2x 2" to 3/4" Bushing
2x 3/4" Barb


example with another hole at the top to remove the excess air pocket (the red tube would either go to the sump near the pumps intake or into a maxi-jet pump in tank)


im currently pumping around 500~600 gph or w/e the 4/10 setting on a Jecod DCT pump is, no Co2 bubbles. only bubbles im getting are produced from the venturi mod i have on my outflow pipe.
 
#10 ·
tom barr conducted a few tests on the "air" bubble at the top of reactors and concluded that it is co2 and that it is pretty much unavoidable (assuming that you are pushing enough co2 to achieve a 1pt pH drop in couple of hours after lights on). c02 is relatively difficult to dissolve, particularly as the ppm increases; that's why we see the bubble gradually accumulate as it approaches lights off. you can try to recapture the excess using tom's "dual venturi" mod on your reactor or something along singalongwithtsing's suggestion about attaching to powerhead. both methods, however, will introduce co2 mist in the tank.

i am running a modified rex reactor. total height is 17". pushing 230gph through it. i'm not sure how many bpm co2 i'm using but i do get a 1pt pH drop in a couple of hours. i get no co2 mist entering the tank, and i do get the bubble accumulating as lights off approaches.

just read op's reply. go to tom barr's site and look for dual venturi external reactor, got pics. it is a sticky in the articles section of the forum. i modified rex's using tom's co2 input method (rex's allows you to have it stand on the floor). it is effective as methods come and the only sound i hear is from the hum of my pump (maxijet 900) and a little trickling as the bubble accumulates.
 
#12 ·
CO2 reactors are really not a very complicated piece of equipment. It's amazing the degree that some go to to over complicate them. PlantedRich's post was basically dead on. If it's properly sized there won't be much of a build up and even if there is, it's usually other gases from the water that make up the bubble since the CO2 has long since been dissolved. If the bubble makes it's way all the way back to the canister then the pump is vastly underpowered.
 
#14 ·
I'm making a Cerges style reactor and am half considering trying out an "internal venturi" at some point. If you drilled through the outlet side of the housing, and used a piece of notched rigid airline tubing, or even a bend/elbow of some kind, the water flowing passed it on the way out of the filter would creature a small vacuum that would then pull the gas out to the desired level as set by the depth of the tubing.

My concern with this, at least in my plumbing setup, is that this won't produce the micro bubbles that would be easily transported out of the plumbing and may end up in gas pockets just getting caught somewhere else down the line.

I had also considered using a venturi tee for pool and spas, but I'm just not sure this would work well without a higher pressure as any back pressure would basically stop the vacuum.
 

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#15 ·
I'm pretty sure before that venturi idea would do anything you would start losing head pressure. With the type of pump a canister filter uses, the head pressure is very small to start with, so any loss of head pressure is significant. That's why it is a good idea to minimize the elbows, and other short radius bends in canister filter plumbing. When you lose head pressure the output flow from the filter drops, and with any significant loss of head pressure you get very little flow from the filter.
 
#16 ·
forgot to mention in my case this is running separately from the filter on it's own pump.

Another thing to consider is if the gas pocket has any pressure behind it, if it does then that will also help push the gas out through the output.

like I said I'm not sure if it would really work but I might give it a shot at some point just for kicks.
 
#20 ·
It's not complicated, it's all smooth angles to reduce flow restriction, those aren't pumps, they're heaters. Hydor ETH series.

water will be pulled through with a pump on the top right side, the Tee fitting won't return water to the reactor due to there being suction on the lines from the pump. But that's also just a diverter loop so I can adjust how much water flows through the reactor and how much water will bypass it.

I removed the reactors pressure relief valve and that's where I'll inject CO2, I'm going to drill another hole so I can install a gas pocket relief line that will run to the pumps venturi.
 
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