# diffuser vs reactor



## bfhoney (Jan 12, 2014)

I have a question for the wise, 
I am currently using an in line diffuser in my 80 gal set up. I have to start the co2 2 hours before the lights to get near 30ppm and I have a lot of fine bubbles coming into the tank so I gather some of my co2 is not dissolving in the water. Would a reactor do any better? its crowded under the cabinet so Its not easy to work in there but if it will make a difference I'll do it.
BTW I am doing EI have high lighting and get a small amount of bba hence the question.
Thanks
BillS


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## hoppycalif (Apr 7, 2005)

I think the primary advantage of under-the-tank reactors is that they are out of sight. No question they do work well at getting a lot of CO2 into the water, but a small water pump/powerhead, with holes drilled/burned into its rotor, also does that job very well. The advantages of the powerhead/pump are the extremely small CO2 bubbles you get, which last a long time in the tank, and the ease of installing and working on it when you need to.


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## khanzer22 (Nov 30, 2009)

It's really up to you, there are pros and cons for both and I've tried both... 

From my experience, reactor works very well if you have a big and long tank, like 120gal for example... It will disperse CO2 in the water nicely plus you have enough space under your tank cabinet for the setup... Diffuser, it does it job too and I like it using on smaller tanks, 90cm length and below, and aesthetic wise I like it on rimless tanks  And yeah, no extra clutter in the tank cabinet...


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## tiger15 (Apr 9, 2017)

I use Tunze reactor, which is a power head driven reactor placed inside the tank. You can easily imitate and diy.

https://www.amazon.com/Tunze-USA-7074-500-Diffuser-Compact/dp/B00H6YW0QK

Nearly all inline reactor is connected externally to canister filters. I do not use canister nor like the idea of under the cabinet plumbing of any sort for fear of leak that drains my tank, specially it is located in my living room. I trust only HOBs without external plumbing and Tunze style reactor fits my need and provides excellent co2 dispersion.


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## hoppycalif (Apr 7, 2005)

I have heard of "Tunze reactor", but I never looked into it. That looks like a great DIY project, which I may play around with to avoid boredom! Thank you!


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## tiger15 (Apr 9, 2017)

Tunze reactor is similar to Barr’s venturi reactor without the feed back loop. It’s pricy but comes with a powerful magnet that is a third of the cost allowing one to secure it anywhere in the tank. I placed it at the lowest point in the tank to maximize the pressure to desolve co2 and and the longest distance to rise up. In my search, only two companies make power head driven reactor and Tunze is a German company that makes a full line of aquarium equipment. I like it’s compact size and performance, but if you have a 6 ft tank, you will need two.


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## hoppycalif (Apr 7, 2005)

I plan to make this, with some 3/4" diameter acrylic tube I have, and using a very small submersible water pump, which I have one of. It would add the recycle effect that Tom Barr used for external reactors, to a Tunze type design. The little pump has suction cups to hold it in place, but I might need to use a magnet. As far as I can see, it should work better than my current reactor. This is the pump (or a similar one from my LFS) https://www.amazon.com/gp/product/B06XSK73D3/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1


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## tiger15 (Apr 9, 2017)

I don't know if Barr'feed back loop is a good idea as it may shorten the life of the impeller due to cavitation effect.

https://en.m.wikipedia.org/wiki/Cavitation

When I run the Tunze reactor at high bps, an air pocket will build up in the tube over time. The capacity of the reactor is limited by maximum expansion of the air pocket to the full length of the tube, which is about 6 bps in the bubble counter, and 3 bps in the reactor tube.

I don't think the air pocket is all co2, but likely contains O2 and N2 too due to air stripping effect of rising CO2 bubbles. My reasoning is that the air pocket may take couple hours to dissipate after stopping co2 injection, suggesting that it contains less soluble N2. Also, right after WC, an air pocket will build up from off gassing from the new water without co2 injection. So the idea of having a feed back loop may not contribute to dissolving significantly more co2.


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## hoppycalif (Apr 7, 2005)

Right now I use that same little pump to chop up my CO2 bubbles and spray them into the water. The only difference this will make is possibly reducing the amount of CO2 that still goes into the air, as the micro bubbles pop at the water surface. I'm planning to set it up so the excess air can float up out of the pump inlet grill, but the much less volume of CO2 stands a chance of being sucked into the pump rotor. I may have to tweak it a bit.

I will start a new thread in the DIY forum to stop stealing this one.


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