My two stage CO2 Reactor/Diffusor

[rthien]

Hi Guys,

Kho (shortman) visited my place a couple of days ago and suggested that I share with folks here my two stage CO2 reactor. Kho passed me a Dennerle Cyclo Turbo XL diffusor some time ago as he found an in-line reactor/diffusor that worked better in his tank than the Cyclo Turbo. Thanks so much Kho!

I was using a UP Turbo-Jet reactor myself and saw a lot of visible bubbles meaning that the reactor was not doing a good job. This started my quest for a better solution....

After some experimenting, I managed to come up with the contraption below. The 1st stage being the Turbo-Jet (green) with the CO2 being fed into this reactor. The ceramic rings in the Turbo-Jet traps some of the CO2 bubbles. As the water from the Turbo-Jet is channelled directly to the Cyclo Turbo (clear), the bubbles that escaped the Turbo-jet are caught on the "steps" in the vessel of the Cyclo Turbo to prolong the contact of C02 with water. I'm using a seperate Eheim powerhead to drive this. I wanted the ability to control the flow from my canister filter independently.



Click on images above to see a larger version

Well, I'm happy to say that diffusion of CO2 is highly efficient with this setup. The only minus is that you have to clean the reactors quite often as the water channelled through the reactors are not filtered. Yes, I guess I should aim for clean and crystal clear water.... as they say, easily said than done. I've borrowed a diatom filter, that should help me to "polish" up my water!

Oh, I guess it is a little pricey too! Just know that I'm making use of what I already have.... newbies may want to look at an external reactor (water filter canister type). I kinda like looking at the bubble of activity going on in this contraption... so nah, no external reactor for me until I get a huge tank in which this contraption will not suffice!

Anyway, all suggestions and comments are most welcome!

Happy and prosperous 2005!

Cheers,

Roger

[zmzfam]

Roger,

where's the inlet of the pump? You could plug the inlet with foam filter material.

[FC]

Roger,

Reducing maintenance
- Is there any reason that you are not using the filtered water (from the canister filter)?
- remove the ceramic

My opinions
- the Dennerle reactor alone should already be sufficient and more than 95% efficient. That said, you need to tune the outflow (need trials/experience) to get that.
- the first stage reactor may accumulate undissolved gas which you need to purge periodically. Retrofit a air pipe (with valve) on top of the reactor.

[PeterGwee]

Roger, did you test the response time of your two stage internal reactor? Response time is very critical in a well running tank in my opinion and BBA is never an issue.

How long does it take the CO2 system/reactor to hit 30ppm from ambient levels (3-4ppm)? I tried several internals without much success on the response time issue but nailed it with a large external 3.5" dia. x 10" long reactor with high flow rate (225g/hr with a maxi jet 900...flowrate probably less due to turbulence and head loss)and CO2 fed at the suction side of the pump. It took roughly 1 hr to hit 30ppm from ambient levels. I'll continue to verify it for the next few days till Tom Barr post me his design.

Here is a quote from APD on the design concept of a good high flow CO2 reactor. Work towards the one with large diameter reactor chamber with high flow rates and low velocity flow in the chamber.

> David Terrell" <Dave at TerrellClan_com> wrote:
>
>>I had posted the original question to the APD, wondering if the
reactor
> would be too short for the flow.<<
>
If a reactor is allowing bubbles to pass through, the most sensible solution
for us is to provide more "residence time" in the reactor. This is generally
accomplished in one of two ways.

The first is to increase the length of the reactor. This is how Hagens CO2
Natural Plant System
(http://www.drsfostersmith.com/Produc...=8981&R=6309&N
=2004+2021+113565&in_merch=1) operates. Residence time in the reactor is
increased by lengthening the distance the CO2 bubble must travel before
exiting. You can do this in your setup by replacing the reactor you have
with 20 or 30 feet of 1/2 inch or larger hose or tubing. Not a very
practical solution for most.

The second is to decrease the water velocity through the reactor. With lower
velocities, the bubbles can overcome the downward pressure of the water
flow, and remain in the reactor until dissolved [Please note the difference
between velocity, measured in distance per unit of time (typically feet per
second) and flow, measured in volume per unit of time (typically gallons per
minute).] One way to decrease velocity is, as you have done, to decrease the
flow rate. This works well, unless you wish to maintain the flow rate as
high as possible. Another way to decrease velocity is to increase the
diameter of the reactor. In this solution, the flow rate remains high, while
the velocity of the water in the reactor is decreased due to increased cross
section. This is the method I use. It results in a highly efficient and
fairly compact reactor.

My reactor is made of clear PVC, is about 12-inches in length, and 2-inches
in diameter. It is placed in the inlet tubing of my Fluval 303. There are no
bioballs, or anything else inside the reactor. The CO2 is injected at the
top of the reactor, and stays there until dissolved in the water. It could
probably be as short as 3 or 4 inches. I have no problem with free CO2 in
the filter.

Just something to think about after you move.


Douglas Guynn
432.368.5411
d_guynn at sbcglobal.net

A government big enough to give you everything you want is big enough to
take everything you have. - Barry Goldwater
_______________________________________________

Regards
Peter Gwee

[rthien]

where's the inlet of the pump? You could plug the inlet with foam filter material.

I've tried putting foam filter material at the inlet of the powerhead but it only took a day to be totally clogged up with dirt/debris.

Is there any reason that you are not using the filtered water (from the canister filter)?

Like I said, I wanted to control the flow from my canister filter independent of this contraption.

Peter, thanks for sharing Tom's reply. This is my 1st experiment with DIY reactors. I'll try to apply the principles which you described. Your approach is way more "scientific" than mine. For me, I'm just judging this from visual inspection ie. I do not see a lot of huge CO2 bubbles escaping from my contraption.

Cheers,

Roger