# DY external reactor problem



## Rub (Jul 14, 2005)

Hi!!!, I have questions for you.
I made my DY external reactor (similar to Gomer´s DY reactor  ) with PVC tube 10" x 2" (25cm x 5cm), bioballs and a difusser airstone ( is in the reactor). Water flow goes from top to the bottom (CO2 is inyected on top). I place my reactor on the input side of my external filter (eheim 2213).
The reactor works well, but the filter begins to do some noise and emits small bubbles (I think that is undisolved gas) in the evening (all is ok during the morning).
What do you thing?????

Greetins


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## Laith (Sep 4, 2004)

I find it better to put an external reactor on the output side of the filter. That way only filtered water is going through it and any bubbles that come out will go into the aquarium and not the filter...


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## Rub (Jul 14, 2005)

Thank you for your answer Laith.


> I find it better to put an external reactor on the output side of the filter.


............why????????
I placed reactor on the input side because I thought that any bubbles would finish dissolving within of external filter..............
what is the best? high flow or low flow water whitin of reactor????

Greetings


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## QuantumCranker (Oct 9, 2005)

The eheims are "impeller in the top" type filters. Air bubbles always float to the highest point that they can. This is where the impeller is in Eheim filters. The noise you hear is likely the CO2 bubble building up in the impeller housing. This is called airlocking and can wear out the impeller pretty fast due to overheating. The only good canister filter for CO2 to go INTO is the magnum 220/350 floor models, not the H.O.T. Their impellers are in the bottom. I hope I helped a little.


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## jonathan (Apr 6, 2005)

I've never tried using an inline DIY reactor, but I'm planning to make one soon. I'm going to try adding a pre-filter to the intake of the filter/tube to reactor. Hopefully this will keep the big stuff out of the CO2 reactor.

http://www.thatpetplace.com/Products/KW/prefilter/Class//T1/F26BA+0558+0011/EDP/5217/Itemdy00.aspx

I bought a few of these whe nthey were on sale for 5.49 for my red cherry shrimp tanks. They have a very fine media so it will catch the big stuff easily.

The only trouble I had with them is when I had bluegreen agale, the sponge seemed to be a magnet for it. I'm looking for a way around that. Maybe on a second try with CO2, I won't get bluegreen algae. I bleached the old sponges and they are still good as new. They seem to be made of decent material.


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## czado (May 26, 2005)

Assuming the filter has adequate mechanical filtration, inline reactor output side keeps debris out.


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## tazcrash69 (Oct 24, 2005)

One other thing is that you want the CO2 to bubble up (counter-current) from the bottom of the reactor. This will give it enough time to dissolve before it makes a big bubble at the top of the diffuser. If you inject the CO2 from the top, you essentially made a really effective bell jar diffuser, and you might get splashing sounds when a big enough bubble is created.


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## TPIRman (Apr 28, 2004)

Rub: The noise is normal for an external reactor. It is annoying, but it is not a sign of a problem. Check out this thread:

http://www.aquaticplantcentral.com/forumapc/showthread.php?t=1956&highlight=reactor+noise

Also, to dispel a couple myths in this thread: there's nothing inherently bad about putting a reactor on the input side. Debris is a problem in theory, but seems to be much less of a problem in practice.

One problem with putting the reactor on the output side is that it can reduce flow. Ghazanfar Ghori and I have both experienced this using an Eheim 2213. The location of your reactor should be decided based on your particular setup, but either side can work just fine.

Putting the reactor on the output side will not get rid of the noise.

The noise you hear is not CO2 building up in your filter. Also, CO2 bubbles are probably not going to hurt your Eheim. Eheims are designed to prevent airlocking, and many hobbyists inject the CO2 directly into their Eheims, using the filter as a makeshift reactor, without any trouble.

In short, don't worry. If you can't stand the noise, you might consider an internal reactor. As you'll see from the linked thread, I have tried to find a solution to the trickle noise on the external reactor and never figured anything out. Wish I could be of more help.


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## NE (Dec 10, 2004)

There is a quite huge difference in the amount of gas that you could dissolve in the water if you have it under pressure or suction (i guess this is not the correct term but i hope you understand anyway).
I was not able to dissolve enough gas to meet my target without total gas build up in the reactor when i had it connected to the suction side, now when i have the exact same setup but on the pressure side, the maximum gas build up is about an inch.
I think There is some kind of physics law that correlates to this as well, I has been discussed in a Swedish forum as well.


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## jonathan (Apr 6, 2005)

Yes there will definately be more CO2 dissolved if you put your reactor in the input side of the filter. Quick chemistry recollection -> for a chemcial reaction to take place there has to be collision of mollecules. Stiring, heating, and increasing pressure (added kinetic energy) speed up a reaction. A filter seems to be a good stirrer to me. :-D

So has anyone used a prefilter and an inline reactor on the input side? I never tried this but I will when I get my CO2 equipment :-D A prefilter will stop all the big junk from getting in. That seems to be the main knock on putting the CO2 on the input side. 

For the other issue (CO2 in the filter) , just be sure your filter is bottom propelled and you'll have a great system.


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## TPIRman (Apr 28, 2004)

NE said:


> There is a quite huge difference in the amount of gas that you could dissolve in the water if you have it under pressure or suction (i guess this is not the correct term but i hope you understand anyway).


Perhaps -- usually turbulence and saturation are cited as the two main factors in CO2 dissolution. Regardless, like I said, input/output side is a decision that really has to be made on a case-by-case basis. If Rub put his reactor on the output side of his 2213, he'd likely be getting significantly reduced flow -- cutting off the nose to spite the face. I think he has it right for now.



jonathan said:


> So has anyone used a prefilter and an inline reactor on the input side? I never tried this but I will when I get my CO2 equipment A prefilter will stop all the big junk from getting in. That seems to be the main knock on putting the CO2 on the input side.


Seems that way in theory, not actually a big deal in practice. I ran an inline filter on the input side for six months with nothing on the intake except the standard Eheim strainer. I had no problems with clogs or debris buildup of any kind in the reactor. Bio-balls just aren't a good mechanical filter, so stuff generally passes on through. As I mentioned, Ghazanfar Ghori ran a similar setup with a similar experience.



jonathan said:


> For the other issue (CO2 in the filter) , just be sure your filter is bottom propelled and you'll have a great system


Again, this is a bit of a myth. Many, many hobbyists inject CO2 into Eheim filters with their top-mounted impellers and have no trouble. I can't speak from direct experience with other brands, but a cursory search of the forums will reveal that many of us are injecting CO2 into Eheims with no ill effect.


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## NE (Dec 10, 2004)

> Yes there will definately be more CO2 dissolved if you put your reactor in the input side of the filter. Quick chemistry recollection -> for a chemcial reaction to take place there has to be collision of mollecules. Stiring, heating, and increasing pressure (added kinetic energy) speed up a reaction. A filter seems to be a good stirrer to me.


This seems to me as the opposites, input/suction side and increasing pressure.

The effect on the suction side is somewhat similar to when opening a syringe to fast and the gas dissolves from the fluid.


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## QuantumCranker (Oct 9, 2005)

Quote:
Originally Posted by jonathan
For the other issue (CO2 in the filter) , just be sure your filter is bottom propelled and you'll have a great system



TPIRman said:


> Again, this is a bit of a myth. Many, many hobbyists inject CO2 into Eheim filters with their top-mounted impellers and have no trouble. I can't speak from direct experience with other brands, but a cursory search of the forums will reveal that many of us are injecting CO2 into Eheims with no ill effect.


There is nothing myth about it really. It is a fact that a bubble of any size of any gas will naturally find the highest point it can in a container of water. If the highest point is the impeller chamber, and, now here is the key, The rate/size of bubbles introduced into the area are large enough then there WILL be some cavitation. Cavitation=NOISE . and will also reduce performance/efficiency.


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## TPIRman (Apr 28, 2004)

The myth is that you need to be "sure" you have a bottom-impelled filter. The truth is that a top-impelled Eheim works. (Note that I am being specific about Eheims here because I lack experience with other top-impelled canisters.)

QC, you said earlier that the noise was a bubble building up in the Eheim and that an Eheim was not suitable for CO2 injection. Both of these statements are false. The noise is a normal trickle noise emanating from the reactor, and Eheims are specifically designed to avoid airlock.

As a general principle, you're correct about cavitation. In practice, it is more complicated. Your blanket statement doesn't apply in this case. An Eheim Classic 2213 is a perfectly fine vessel for CO2 injection because of the filter's design. This has been tested again and again by many hobbyists. Most users experience a small "burp" once in a while as the Eheim expels any collected gas, and that's it.

My main point is "if it ain't broke, don't fix it." Rub seem to be asking if the noise in his/her external reactor is a sign of a problem. It isn't -- it's a normal side effect of a basic external reactor.

Rub never said anything about low CO2 rates or poor plant growth. People are recommending the purchase of new equipment and reworking an entire setup to increase efficiency when there may very well be no need for it. This can be so overwhelming.

It is great to discuss the merits of different setups -- for instance, I find NE's discussion of suction vs. pressure pretty intriguing. But it is another thing to recommend costly/time-consuming equipment changes when they may not be necessary. There are a number of ways to skin this CO2 cat (vive la difference!), and while some methods may be more efficient than others, that doesn't mean that a non-optimal setup won't be "good enough." Rub has said nothing to indicate that his/her setup isn't "good enough" in terms of plant growth.

My message to Rub: relax. Watch your plants grow, and make changes to your setup slowly. If you don't like the noise, you might try an internal reactor, a diffuser, a Venturi loop, etc. (you can find more info on these with APC/Google searches). There is nothing in your current configuration that is likely to cause disaster, so there is nothing that you absolutely *need* to change. This means you can take your time and spend your money carefully. There is no one "true" way to get CO2 right. I have learned that the hard way.


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## QuantumCranker (Oct 9, 2005)

TPIRman said:


> Rub seem to be asking if the noise in his/her external reactor is a sign of a problem. It isn't -- it's a normal side effect of a basic external reactor.


Well, OK but Just FYI, Actually, he said it was his filter making the noise. Re-read the first post. Aw what the heck, Let's just go have some beers!


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## TPIRman (Apr 28, 2004)

QuantumCranker said:


> Well, OK but Just FYI, Actually, he said it was his filter making the noise. Re-read the first post. Aw what the heck, Let's just go have some beers!


That's true. I thought he was talking about reactors' diurnal splash noise, but maybe he was talking about the "burp." Regardless, Rub, you'll be fine.

And QC, beers are on me!


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## Rub (Jul 14, 2005)

Hey!!!! thanks for all your coments 

Well, my reactor works very well ( the growing is good and the plants is perling all the day.......). My problem is the noise that is produced in my 2213 filter. Is peculiar but only it makes noise in the evening (during the morning is all ok). I put the reactor on the input side of my filter because I thought that if left bubbles of the reactor, they would dissolve in the filter.

Note: I have two external filters in my aquarium. Eheim Ecco makes a biological filtration. Eheim 2213(was a present) makes of powerhead of my external reactor. I'll put the reactor on the output side, because a low flow is not a problem for me. I will prove it to see if it works fine.

Greetings from Spain.


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## TPIRman (Apr 28, 2004)

You were indeed right about the noise, QC -- my apologies. I hate it when people don't read the posts thoroughly, and now I'm guilty!


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## QuantumCranker (Oct 9, 2005)

Hey, no biggie! I have been guilty many times in the past. But since it is occurring in the evening, that is certainly buildup of CO2 in the impeller. But, as long as it burps it out every now and then, no big deal. Except, of course, the noise.


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## greenfish4 (Nov 7, 2005)

sorry to beat a dead horse, but is a venuri loop on an external reactor the tubing that runs from the highest point back down to the lowest? would this give the gas another chance at dissolving? I believe I read this on one of Barr's post.


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