Dual venturi DIY External CO2 reactor

[Tom Barr]

This unit cost about 20$ due to using Clear PVC housing, you can use solid 2" pipe if you wish.

You can find all the parts at any Orchard Supply Hardware or Home Depot.

Two: 2" slip to 1/2 threaded bushing
Two: threaded 90 elbow 1/2" barbed
About 10 Bioballs if desired
12" of rigid 3/16" air line
PVC glue
3/16" drill bit
Drill
Powerhead or canister filter etc

This works very well in sump areas also.

 

[Tom Barr]

So assembly is very easy as are drilling two to three 3/16" holes.

As you can see from the pictures, we drill two holes on the top.
You insert a 12" long piece of rigid 3/16" tubing and glue the top and bottom with the PVC glue. This seals it in place and is the CO2 inlet.
I chose clear PVC(available through Aquatic Ecosystems) so I could use this like a bubble counter. I can see how many bubbles per second are going into the reactor.

The other hole can be used for two different functions.
It merely has a 3 " piece of rigid air line tubing inserted and glued in place.
It can have a simple ball valve(irrigation drip valves work well here) and allows you to remove any gas build up manually. It also allows control of the gas being sucked out if you want to use this for degassing the chamber with venturi suction.

This prevent any gas build up inside the venturi External reactor.

Optional:
Another hole can be drilled, about two inches from the top of the reactor. This can be fed to the suction side of the powerhead to degas the chamber once the gas builds up to this preset level.

The usefulness of this method is incredible. Degassing the chamber via the venturi
loops allows the chamber to have much reduced gas lock and backpressure, as well as providing a fine gas mist once the gas buld starts affecting efficiency.

This waste some gas later in the day but adds the mist directly to the tank and plants. The effect is phenomenal.

This design is based on a closed loop like the internal venturi reactor.

Both are 100% efficient until the gas starts to build up and then it starts degassing the bubble into mist and ejects it out into the tank later in the day.

 

[FacePlanted]

So do you only use one or the other of the "venturi outlets" (the one on top vs. the one on the side)? Or can you use both of the short airline pieces to create 2 venturi loops?

Do you only need the second outlet 2" down if you are using the smaller top outlet as a relief valve?

Thanks.

-Mike B-

 

[Tom Barr]

You use only one of the venturi holes generally.

No need to use the lower one if you use the upper.

The article and pictures are not done yet, so I'm going to move some post around here a bit.

Regards,
tom Barr

 

[FacePlanted]

Is there a way to construct a venturi loop without the placing the end of the loop on the intake side of a canister filter/pump/impeller? Can the end of the venturi loop be fed into somewhere after the canister filter/pump? Somewhere on the return line?

I ask this because I am using the pressurized Rainbow Lifeguard Modular Filters with a Quietone 3000 pump and I dont think that the microbubbles will be able to be forced through the micron pleats in the mechanical module. And that it would just create a bubble that I would need to bleed out of the module.

Is there some way I can still use the venturi loop with this type of setup/filter? Or will it only work with the suction that is created by the intake of the pump and smashed up by the impeller?

Thanks for your help and patience.

-Mike B-

 

[mrkookm]

What would we ever do without you! I just built a reactor based on your design and I am veryyyy happy with the results! I get a lot more mist I can barely see 'have to go up real close and look real hard' perfect bubble size. I even like hearing the water inside churning sounds as if co2 and water is getting truly mixed in and my plants are telling me they love it! Crazy pearl even more than before!!

I have this setup on a 90g w/ sump. My reactor sits in the sump with is own pump feeding water in and the misty water output hose I have inserted into the bulhead that feeds my system pump so nothing is wasted or circulated in the actual sump.

I have used many reactors in the past and this is the only one that has ever worked well for my demanding system!

 

[Tom Barr]

This should outperform every other brand or reactor out there.
Most have no clue as to the venturi and mist idea.

Those are my designs.
The internal reactor is similar.

Degassing the gap inside helps a great deal in the effectiveness.

Regards,
Tom Barr

 

[mrkookm]

Degassing the gap inside helps a great deal in the effectiveness.

I agree with you 100% on this! Simple but very effective....keep the ideas rolling TBarr!

The output coming from my reactor gives a new meaning to what we call 'misting'

 

[Tom Barr]

Well, it does get more out of the misting and keeps it running full time when the reactor is on.

The good thing is that it's less wasteful than the internal method.
Some collection and coalescence occurs in the sealed chamber as well as recirculation to a much greater extent than the internal design.

You can also set the desired levels of recirculation to increase or reduce the misting by adjusting the valve on the venturi loop. You can also place the venturi inlet hole higher or lower depending on your goal.

I'll bring this unit to the Local SAPS club meeting this Nov to show folks how to make it and so they can see it up close up and touch it etc.


This is the entire reactor:

This is the option to use the lower venturi intake:

This is the option to use the top venturi intake method at about 1" depth for the gas collection bublle vs 3" in the above example:

Missing from pics are the venturi ends are a ball valve irrigation drip to control the flow and also to turn off the Gas and seal the end when not in use.

Note: you can modify the AM 1000 and the Dupla reactors by making a venturi loop to the powerhead or pump driving the flow through.

For 10-15$, it's hard to beat this product and design.
This is good to about 180 gallon or so with 400-500gph.

Regards,
Tom Barr

 

[hani]

HI, just woudring how the degassing works? will the extra gas go back through the intake of the pump and goes back to the reactor again?
hani

 

[Tom Barr]

Yes, it basically recirculates it again, but this time is produces a finer mist that is able to pass through the reactor out the bottom and exits.

This "recalcitrant gas" is not pure CO2 and tends to build upo in the latter 1/2 of the day inside all CO2 reactors.

By purging the gas, we are better able to add CO2 and reduce backpressure, it also grinds up any CO2 that's present in the "recalcitrant" gas and any new CO2 that cannot dissolve faster enough without building up inside the reactor the normal way, then the venturi mist kicks in.

So this venturi adds another layer of dissolving CO2 as well as purging the reactor as it builds up in the latter 1/2 of the day.

You can set this level of purge also to any depth inside the tube you wish, the holes can all be drilled into the top also, and then insert however long a piece of 3/16" rigid tubing you want to a desired depth before the venturi loop starts to work.

I generally allow 2" or so, some less, some folks more.

Regards,
Tom Barr

 

[FacePlanted]

The extra pictures are good. They give me the idea to make this in a sort of HOB kind of way. I really want better mist than my glass diffuser, but I dont think this will work with my pressurized, pleated filter module. I have a quiet one 1200 pump I could use, but I think the 300gph w/ 0 head would be too much for my 29gal.

Any ideas??

By the way, how long is the clear 2" pvc tube?

Thanks!

-Mike B-

 

[Tom Barr]

The PVC tube is 12" long x 2" Dia. You can use a larger tube anbd larger in/out fittings, and higher flow etc for larger tanks, and the same thing except smaller for smaller tanks etc......

For a HOB variation, (there are many) I think a venturi loop may be more appropriate. That is yet another method I've sort of suggested and pushed within the hobby for CO2 diffusion and is based on the CO2 mist idea.

Another simpler idea for the venturi: simply drilling a hole into the return line right after the filter, placing a good seal and tapering the tip of 3/16" rigid tubing that goes into the return line, make it very fine by heating the tip and then stretching the tip out. Much like pulling pizza cheese etc apart. It should get progressively smaller.

Or you can pinch it but make sure there's some hole available. I also bend the 3/16" tubing away from the current to allow the bubbles to ripped up and stretched out as they come out by the current and it seems to produce less backpressure into the tubing towards the CO2 gas system. Still, the venturi mazzi valve is a wise option, but on smaller systems, not that applicable/cost effective.

This reactor is very cost effective though.
You can likely modify the venturi loop on the reactor "in line" by placing the venturi hole right after the filter and place the reactor farther down the line for the return.

As long as the hole is in a region of tubing that has much faster flow than the reactor tube, that should cause a gas pull and a venturi mist. Note: it will not be as effective as the pump drawn suction etc, but should do the job in line.

I'll post a pic later for a set up and the venturi loop etc.

The other idea is to use a disc or small glass bead stone inside the tubing in line.
CAL Aquaria Lab's makes a small disc inside a glass reactor bulb, rated for 160gph or less, sort of fragile but nicely made. Runs about 60$.


Regards,
Tom Barr

 

[FacePlanted]

YES! Thank you so much for that post! This is exactly what I have been wondering. I thought that putting the loop after the filter, and point it with the flow might work. I'm glad to hear that I can use the venturi loop that way. That is exactly what I wanted to hear.

I tried to place a diffuser into a reactor that I made, but the reactor was too narrow and short, and the flow was too much. Very tiny bubbles did shoot out of the outlet, but not enough. And I had to crank the bubble count. Even still, the co2 concentration never got high enough.

I will make one the correct way now. Wider tube, and a makeshift venturi loop after the filter.

Thanks again.

-Mike B-

 

[Gerryd]

AM 1000 mod?

Hi Tom,

I have an AM 1000 for my 180gal (dual overflow) driven by a 500 gph Mag drive pump.

This unit has a gas exchange ball valve used to release gas buildup. I have NOT seen the need for this on a daily basis regardless of time of day???

1. Am I doing something wrong that it should require more frequent de-gassing?
I've done it before, but not that it needs it daily.......The reactor stays full of water as the pump runs through it all the time, but the c02 is NOT run 24/7 and run a little less than the lights. 1/2 off before lights off and 1 hr before lights on.....

2. Is the modification to REPLACE this ball/check valve with a longer piece of rigid tubing and connect this with flex tubing back to the OUTFLOW of the pump?

3. Won't this just send water from the reactor back to the filter if the reactor is full of water as mine always is? Is the intent to send just GAS through the venturi, or gas enriched water?

4. How did you connect the return loop back to the filter output line? Looks like you grafted it in somehow???

5. The output of the reactor is stuck into the large sponge filter surrounding the intake of my 1800 gph pump that splits to both outlets to tank. Is this adequate? I was concerned about hooking a 500 gph restricted flow (due to reactor) into a much larger pump, that I would be killing the bigger pump by limiting intake.

Sorry if these questions seem obvious or silly..........

I appreciate all of your time and patience.

I have made many other improvements you have suggested to improve my c02 usage and they have all worked well. I think this may be even more optimal if I can understand it lol

BTW, I started EI this week and will keep all posted. New 6500k MH (from 14k) bulbs and drop checker expected by end of this week, so all hardware changes will be done and I can FINALLY verify my C02 levels. Hope to post some before/after pix!

My plants all pearl much more now, even algae and crypt leaves at the very bottom of the tank. This is a big improvement from before, where only leaves close to the surface would pearl......

Thanks again to you Tom and all others who have contributed to my knowledge base and tool kit and have answered my many questions.

 

[Tdon1md]

I'm a little confused. All designs I've seen b4 for the CO2 inlet have showed the injection point of CO2 within 2" of the TOP of the reactor, normally from the side. You suggest using 12" long 2" diameter pipe and a 12" length of rigid airline inserted on the inlet side of the reactor. This will obviously put the CO2 injection point at the BOTTOM of the reactor. Obviously the gas doesn't just exit the reactor. I trust your design much more then that! But does that mean that my reactor is even more inefficient then I thought? I do get quite a bit of mist (large bubbles at times) in my tank. Could this have something to do with why? I also moved my reactor to in intake side of my canister at the suggestion of several folks @ The Planted Tank. You reference putting it on the outlet side, down stream from the venturi return port. Again, was I guided incorrectly?

 

[Tom Barr]

Todd, this is simple design based on counter current contact time.
the reduced flow is due to the larger 2" PVC pipe as water enters the 2" dia pipe.
Bubbles easily rise even at fairly high flow rates as they are about 1/8" to 3/16" in diameter(bubbles).

Fine mist is perhaps 0.1 mm to 0.5mm in dia and do not have enough buoyancy energy to fight the current.

The Aqua Medic 1000 reactor has the same long tube going deep into the reactor, but they only have 3/8" pipe going in/out of the reactor, but they have a gas release valve that can be used and modified to use this same principle here.

Just attach a CO2 line to the gas release valve and snake it back into the impeller side of the pump/powerhead driving the flow through Reactor.

Works like a charm.

Regards,
tom Barr


Regards,
tom Barr

 

[Gerryd]

Mod done - EZ

Hi Tom,

The release valve on the AM 1000 already had a nipple ending on it. I slipped some c02 tubing over it and connected the other end to the strainer of the pump that drives the reactor, so it is just PRIOR to the impeller and sent back to the reactor. I then just opened the ball valve and let it rip.....

Is this the venturi loop you mention?

This was way TOO easy. Now I am thinking I did something wrong

The tubing from the release valve has a constant stream of water going through it.

Is this expected? Or is the expectation that gas only will flow?????

My entire reactor is always filled with water (see prev reply for details),

Thanks again for all of your help.

Tank is looking better all the time

Sorry I am struggling a bit with this......

 

[FacePlanted]

You did it right, Gerry. That is how it is supposed to be hooked up, but for some reason, your reactor doesnt build up gas half way through the day. Either it is really efficient and dissolves all the co2, the flow is really strong and pushes everything out of the reactor--so no gas builds up, or you aren't injecting enough co2 to have a buildup in the reactor later on in the day. Since there is no buildup, only water is flowing through your loop. Usually it will be co2/gas or a mix of gas and water. BUT, if your co2 levels are ok, dont worry about it. If the gas ever does build up, your venturi loop will certainly work (at least how I picture it, it will).

Good luck!

-Mike B-

 

[fjf888]

I have a stupid part question, I apologize in advance. I had a hard time finding a part like your 1/2 threaded elbow that is half white. Does not appear necessary, but just wanted to double check to make sure I was not missing something obvious, looks like I can just connect with tubing. I got an extra of the 90deg black elbow. As an FYI to everyone, I also found that Lowes had everything I needed, Home Depot in my area (DC area) did not even carry the 2 to 1/2 bushings threaded bushings