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

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-

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

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-

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.

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?

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

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......

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-

Mike-B,

Thanks for the confirmation! I feel better

It does work a lot better. I can see the difference via pearling and that my c02 turns off more often than before to get to the target.....

I think the AM 1000 is a good reactor IMO.

I run a 500 gph pump to drive it (Tom's tip) and it is only 12" of flex hose between the pump and the reactor, so the flow through is excellent. The outlet is stuck right into the sponge for the 1800 gph return to tank, so I think the c02 is well chopped and distributed!

Am still playing with c02 rates as my drop checker is still blue

Thanks again to all!