You can use the recirculating Rio 600 or 800 modifications and they have a 6 blade imepller, then you can drill or melt tiny holes in each blade.

I have a plan for doing this for the in line version, as well as having an in tank Rio for this as well to hit the spots I want mist that the normal filter outflow does not target.

When folks come over, or a photo shoot, I can remove those in tank items.
This gives me a couple of redundancy levels.

In line, you need a pump that does not leak, the suction side will have little if any back pressure, so making a loop, much like the venturi mazzei loop, you add this to it.

You do not need a large pump for that and it'll work in line with most any system, or size.

Then you melt the holes into the impellers.

Regards,
Tom Barr

Today I modified my Maxijet 600 to be a CO2 mist machine! I used a small finishing nail to melt only three holes per blade, but they are much bigger holes than a needle gives, and I made sure no holes overlap from blade to blade. Then I took an airline size piece of acrylic pipe and plugged one end with acrylic cement-the high viscosity stuff. Just before it was dry I poked a needle hole thru the center of the cement to get a very small hole for CO2 to bubble through. This I used acrylic cement to glue into a hole I drilled into the intake tube for the powerhead, so it acts like a crude venturi. I connected my vent line from the external reactor to that. It is now running in the tank, giving a faint buzz as each CO2 bubble goes through, and the tank is now seltzer water. The added circulation is still considerable, even with the drilled paddles. Now I need to adjust the CO2 bubble rate so I don't kill the fish.

I like this much better than the Barr Internal Venturi reactor - it is much smaller, no clear tube to grow biofilm on, and it really generates the CO2 mist, with CO2 that would otherwise just sit in the top of the external reactor. I'm a fickle "lover" though, so I may get over this love affair too!

I have a Rio 800 (RVT), but I can't figure out how to get at the impeller ... I'm afraid I might break it. Anybody have any clues?

Yes, the trade off is better and actually easier to DIY than the internal method.
So the only way someone will steal this idea, is to make powerheads.

So anyone can DIY a powerhead anyway, and then it's easy.

Now, setting up a similar thing in line is all that needs some detailing out and then it's a wrap.

I'll be doing one sometime soon (For the 120 and the 180 I'm doing).
I'm thinking of using a Danner Mag drive 250 or 350 GPH pump and make a loop with some tubing mods to make a semi venturi intake.
That will be a 1/2" line ball valved off loop from the the 3/4" return lines.
The heater is also 1/2, so I'll have another 1/2" loop split there.
A check valve for the CO2, plus solenoid+ minimal pressure inside the Danner mag drive when the CO2 and pump are off should help prevent any leak related issues.
They seem pretty decent as far as leaks go in the past.

I'm mostly worried about the seal on the Mag drive with 3 ft of head in the line.
When the pump is running, the pressure is suction in and out.
But I'll shut the pump off at night I think.
I could leave it and rely on the solenoid.


Regards,
Tom Barr

The powerheads I have worked with have a twist off compartment that holds one end of the rotor. You have to be able to get to the rotor, because you need to clean it and the inside of the driving coils or it eventually locks up. The removable part is the part with the inlet (center) and outlet (outer) passages. I had to use a pair of pliers, gently, to turn the one on the Catalina powerhead so it would come off.

Some have the flexible blades like the Rio's Rejuv systems.
You have to hold these and then melt the holes in.



Regards,
Tom Barr

Yep, that's what I have ... hinged flexible blades. The hinged blades sure seem small. I could probably get 9 holes in each one if I used a needle (and was very careful). If I go with a 1mm size, I'll probably only be able to get 4 or 5 holes in each one. I might alternate blades and do a combination of both sizes of holes. I'm wondering if a sewing needle sized hole would even do anything ... perhaps it's too small.

I've been looking into trying the needle wheel method for distributing CO2 with a little powerhead. However, I've been wondering why a simpler solution would not work and I cannot think of one.

I have a canister filter. If it is strong enough, could I modify the impeller to be a needle wheel and then simply run the CO2 hose directly into the filter intake in the tank (just put a hole in the prefilter and run it thru)?

I do exactly that, except I haven't bothered to modify the impeller of my canister filter. I get complete dissolution without any buildup of CO2 in my canister. It's like an inline PVC reactor except that it happens to have filter media in it. It's worked well for me, so I've never wanted anything more complicated or involved. Simple is good, right?

You reduce the flow rate, but likely not a lot unless you really maul the impeller.
But yep, this should work.

Regards,
Tom Barr