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Discussion Starter · #1 ·
I'm interested in a discussion on this topic - where folks might put, or think about putting, their inline co2 reactors.

As I see it, the filter intake position might trap debris if you are using bioballs. Also I've heard claims that there would be added stress to a canister's pump (?).

On the other hand, the return line position seems to really slow down the flow of the filter. This makes sense to me since the water has to make 2 extra turns.

So -- what's your take?
 

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Discussion Starter · #3 ·
Any other thoughts/experiences? I know there are folks with both, and I'd love to consolidate them all into one thread...
 

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DC is building an inline reactor for me that will be go on my return. Since this will be my first inline reactor experience... I'm not sure which is better. I would THINK that it would be better to put it on the return and not feed directly into the filter itself since it may get 'beaten up' in there.

Perhaps DC can chime in on this one. I would like to see more people respond to this thread... there's got to be more???
 

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Majority of folks put it on the return. I haven't heard of anyone putting it on the intake side.
 

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Put it on the return. I just went through this very issue. To get the best absorption you need to have the water running into the top of the reactor and out the bottom and have the CO2 being injected into the top. This way the CO2 will be wanting to rise to the top but will the current will be fighting to push it down. In this way there is more contact with the water and the bubble will absorb much better.

Here is my thread on it. It may explain things better. Rex weighed in on this.
http://www.plantedtank.net/forums/equipment/44825-inline-co2-reactors.html
 

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I suppose a reactor could act as an inlet to a water pump or a filter ,all it needs is a strainer attached to it and it could be hung on the back of the tank, .but I always have used DIY reactors on the return side only because pumps are more effective pushing water than pulling.
 

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Discussion Starter · #9 ·
Well, I believe the intake line to be a better choice, so long as there are no bioballs used in the reactor. I know Rex doesn't use bioballs and doesn't deem them necessary for 100% dissolution of co2.

eklikewhoa - I don't think gunk building up in the reactor will be an issue, since there are no bioballs.

Anthony - I found this design using google. It suggests using the reactor on the intake. It seems that no one on this forum would think of it...and I want to know why.

ILuvMyGoldBarb - Thanks. I was a (small) part of your thread, and I think bob seemed to even agree with me .... without bioballs, if htere is any advantage to putting the reactor on the intake rather than the return, then it shouldn't make a difference...

distrbd - well most intake lines have a built-in strainer. I'm interested in your statement that "pumps are more effective pushing water than pulling". Is there any data or scientific law that supports this statement, and proves that it is relavent to this discussion?

Here's my argument: The main complaint I hear from folks with inline reactors is that the flow from the canister filter is reduced, sometimes to the point of requiring more filtration/circulation. That just negates any good we might have done by getting a reactor out of the tank, by putting a powerhead/2nd filter in the tank!

I would argue that the reduction in flow is partially due to the fact that the pump now has to overcome 1)More friction losses due to entrance/exit from the reactor, and 2) more head. I don't have any calculations to prove that, mainly just suspicion at the moment. Conversely, with the reactor on the intake it would seem that gravity does the work. In fact, I don't think the pump has ANY more strain on it due to this design.

My other point is ease of construction. Instead of building 2 90/180 degree bends into the reactor to "loop" the flow, the intake design is a straight shot down....no hassles.



Thoughts? Comments?
 

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Here's my argument: The main complaint I hear from folks with inline reactors is that the flow from the canister filter is reduced, sometimes to the point of requiring more filtration/circulation. That just negates any good we might have done by getting a reactor out of the tank, by putting a powerhead/2nd filter in the tank!
the way i see it... the main purpose of the filter is too FILTER (mech, bio, chem, etc), not to act as a CO2 reactor or pump for 5 different in-line accessories. they aren't rated for lots of head, because that's not the way they were designed. if you need something to drive those things, why not get a nice eheim or other external pump? it's probably a lot cheaper than the nice canister filters people use, will provides less stress on the filter motor, and subsequently more longevity.
-snafu
 

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Discussion Starter · #13 ·
snafu - I think you are right we are asking too much from the filters sometimes. I personally have an xp3 on a 29g, so I've got no problems with reducing my flow a bit :) Like most other things with this hobby, I'm treating this as somewhat of a scientific experiment.

I think the flow problem arises when the filter is purchased for a tank, and the inline reactor is an after-thought...the whole goal of which is to get stuff out of the tank and utilize what you already have. In a perfect world, the canister would be oversized to the point that it wouldn't matter. But this is not always the case, and we all know how important circulation is in a PT.

Another point I'd like to make is that my mind, limited as it may be, cannot conceive of a reason why the intake line design would add ANY stress/work at all for the canister's pump -- no extra head, very little "friction" loss. If anything, this design would comply with snafu's point of "don't overwork the canister", not contradict it!

I'm waiting with bated breathe for reasons why the intake side did not work for Rex or anyone else for that matter...
 

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With an XP3, you might notice air building up in the canister housing if you connect it to the intake. I agree it would be easier to implement, try it... if your filter starts to choke and airlock, you know why.

It might work if the reactor causes no restriction of the flow. This would be tough to accomplish, since usually we use hose barbs to connect things which already reduce the diameter a little.

I think it depends on when your tank becomes O2-saturated (visible when tiny bubbles start to float through your tank). If this happens early, say at noon, and restrictions on the intake side increase the negative pressure within your filter, O2 gas will be pearl out of the water, and accumulating in the housing.

If your filter keeps working away quietly, you succeeded.
 

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Discussion Starter · #15 ·
Wasserpest - thanks, great explanation regarding the restriction of the flow. I get a funny feeling that might happen.

Oddly enough, I wonder if it isn't already happening.... In my xp3, the water level in the filter gradually falls so that every few days, I have to "burp" it. Is this the effect of degassing o2? Am I in danger of damaging my impellar/pump assembly by letting the level fall 1-2" in the media chamber?

I don't have anything restricting the infow right now, except for a sponge over the intake (baby shrimp life saver).
 

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The sponge could be the culprit. With the strong flow it will probably clog fast, you won't notice because the filter output is still plenty, but the negative pressure inside the filter will cause that accumulation of air.

Instead of a sponge, you could try to find a diffent intake strainer, bigger size with smaller holes to distribute the sucking power more evenly. And keep it clean of course.

I am getting used to Shrimp in my filters. When cleaning the Filstars, I take the media baskets out, then carefully empty the canister until only a bit water and shrimp are left, then run the rest through a fine net. Hang the net into the tank and let them all climb out, rinse and repeat :icon_roll
 

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Discussion Starter · #17 ·
thanks again, Wasser. So what I hear you saying is that the symptoms I have now (air in the media chamber) are possibly the same symptoms that I might see if I put the reactor on the intake.

Sounds like first I need to eliminate the sponge (shrimp get eaten, anyways :) ) and see if that takes care of my air pocket. If so, I'll try the reactor and see what happens.
 

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Well, I believe the intake line to be a better choice, so long as there are no bioballs used in the reactor. I know Rex doesn't use bioballs and doesn't deem them necessary for 100% dissolution of co2.
distrbd - well most intake lines have a built-in strainer. I'm interested in your statement that "pumps are more effective pushing water than pulling". Is there any data or scientific law that supports this statement, and proves that it is relavent to this discussion?

I copy & paste a paragraph from the link below:

http://www.bbc.co.uk/dna/h2g2/A476921


In a centrifugal pump, the direction of the discharge is at a right angle to the direction of the suction. This is achieved in a different way from an axial flow pump. When liquid flows into a centrifugal pump, it moves onto an impeller, which is similar to a merry-go-round. The impeller spins, causing the liquid to get flung out away from the impeller similar to one getting flung off from a fast-spinning merry-go-round. The liquid then is channelled to the discharge port by a circular casing around the impeller. Since the fluid is flung equally in all directions, the net increase in velocity is zero. However, as the fluid does now have more energy than it did when entering, it gets discharged with more pressure than it entered. A way to imagine this is to think of inflating a balloon. Once inflated, the air inside the balloon isn't moving, but is under pressure and does have energy. Letting go of the balloon and having it fly around and deflate will demonstrate the stored energy the air has.
 

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The way Rex style DIY reactor works is the water entering the reactor is suppose to break the co2 in to micro bubbles and dissolve it as it leaves the reactor,so if there is no water pressure,then the co2 will only get partially dissolved,at least that's how I understand it.
 

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When I had my first reactor on the inlet side I was getting CO2 into the canister. And for some reason the canister would break siphon all the time. You should never restrict the flow of water on a siphon feed canister filter.
 
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