Best Place To Inject Co2 In A Sump.

Andrew T

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Jul 15, 2015
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As the title says, I’m looking for the best place in my sump to inject CO2.
I have a bean animal overflow with the drain 1” under water.

The drop in between baffles is no more than 1” so water gently flows over them, no splashing.
I suppose the best place to inject Co2 would be the first baffle where the main drain is to have maximum CO2 diffusion with minimum to no mist/co2 bubbles by the time it returns to the tank?

The initial plan was to run a GLA in-line aluminum diffuser on the return line but I’ve used the similar UP-Aqua in the past and Co2 mist was just too much.

I was thinking maybe a ceramic disc stuck to the bottom of the sump and just rely on the sump to break down co2 bubbles by the time they reach the return pumps?

What do you guys suggest?

Sorry for the long post!
 

Tim Harrison

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Sumps aren't really the most efficient place to inject CO2, too much off gassing; you'll go through a lot of gas to get optimal conc in the tank. Even tanks with sumps that inject directly in to the tank will loose far more CO2 than tanks with canister filters. But that said, if I were you I'd inject directly below the outlet back to the aquarium. I would have thought that the cavitation created by the pump impeller will help dissolved the gas in to solution so the mist won't be so apparent.
 

Andrew T

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Jul 15, 2015
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Seattle
Sumps aren't really the most efficient place to inject CO2, too much off gassing; you'll go through a lot of gas to get optimal conc in the tank. Even tanks with sumps that inject directly in to the tank will loose far more CO2 than tanks with canister filters. But that said, if I were you I'd inject directly below the outlet back to the aquarium. I would have thought that the cavitation created by the pump impeller will help dissolved the gas in to solution so the mist won't be so apparent.
I see...
There’s no perfect scenario, I used to run a canister filter and lily pipes and surface scum was always a problem...
Surface skimmers were an eye sore too even though they worked.
Now I’ve got crystal clear surface and arguably less tank clutter but will burn more CO2;

I believe gas exchange should be way better with this setup.
Really don’t mind refilling the cylinder a little earlier than needed but get the “other” benefits.
I just didn’t want to see the fizz in the tank. I guess I’ll try an in-line atomizer on the longest return line and see what that gives me.
If not, build a reactor and try it that way...

Tim, I also believe different sump designs and overflow configurations will yield different results as far as CO2 loss goes and sumps can’t be generalized.
Some will be more turbulent and mix way more air with the water thus losing more Co2 where a full siphon configuration with minimal water drop from baffle to baffle or overflow box will be way more efficient in this regard.
Hoping to find out soon enough, was just wondering if there’s something else that I haven’t thought of yet.

Thanks Tim! Will keep this updated after the dry start is over and be finally injecting Co2.
 
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shoggoth43

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Bean or Herbie should off gas far less CO2 than a Durso variant setup will. I need to drill the tank for a new overflow and I’m building a new sump that will use mattenfilter “plates” with minimal drop. The largest drop will potentially be into the pump chamber depending on the water level.

Injecting the CO2 before the sponge plates would definitely eliminate any mist going into the tank. Injecting just before the pump should theoretically chop any mist even finer and hopefully diffuse it faster/finer. It’ll be interesting to see how that will work. It should just be moving a diffuser or a tube from one chamber to the other and seeing what happens.

-
S
 
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Andrew T

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Jul 15, 2015
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How about drilling a hole big enough to fit the co2 tubing into the side of the drain pipe right before it enters my filter sock? So tubing straight from the needle valve to the pipe.
Full siphon and the fact that the pipe drains under water should be a perfect scenario? Or not...
Gotta try it...
 
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brian.brigg

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I'm in the process of setting up a sump with a Bean Animal "ghost" style overflow on my 200 liter tank but I plan using a 20 inch filter housing as a CO2 reactor inline with the return. I have the housing over half full of bioballs in the hope that it will be enough to avoid the 7up look.

I will be interested in seeing how your plan works out as my backup plan involves using the old inline atomic diffuser to feed from a separate submerged pump but I'm worried about how that will work against the pressure from the return pump unless I figure out some sort of venturi setup.

Let us know how it goes.

Sent from my LG-H870DS using Tapatalk
 

Kyalgae

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I have an atomic inline diffuser, I feed a sera 1000 reactor with it. There’s some co2 mist but I would say its 80-90% less, and the bubbles coming out are all the same size. If you still get some misting in your tank you could always drop one into your sump and power it with a small submersible pump, sort of a mini closed loop. There’s a video of one of these things working submersed here. https://barrreport.com/threads/20gl-shallow-tank-plant-farm.14880/page-2#post-148928
 
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Just wondering how it worked out?
I imagine that you off gas most of the co2 in the sump before it reaches the return pump and enters the tank.