I've been doing a lot of reading on Mazzei venturis here on TBR and anywhere else I can find information on them. I currently have a 125G running an AquaMedic Reactor 1000 on the return line of one of my two Eheim 2260 canisters. It works fairly well but I would really like to make my CO2 injection as efficient and uniform as possible, as well as add CO2 misting, and Mazzeis sound like the way to go for large tanks.

My plan is to use one, or possibly two, Mazzeis in a closed-loop system driven by a Little Giant 4MDQ-SC (880 GPH, 10.5 PSI) in-line pump. I plan on having two 1" intakes (one on either side of the tank) merging into a single 1" line into the pump via a PVC 'Y' junction. The return line will be 1/2" out of the pump split into two 1/2" lines going to either side of the tank. I'm not sure if I should use one Mazzei (before the return line splits) or two (one on each of the return lines after the split). I'll be using a pH controller with AquaMedic solenoids on the injector line(s). I'm also not sure which model of Mazzei would work the best with this setup. I'm looking at the Mazzei 584C right now because it has a 1/2" intake/output and a wider diameter bore than the 384. Would I need to use the 384 if I went with two venturis (since the line would be split going to each venturi and pressure would drop commensurately), and is having two Mazzeis even a good idea or is it overkill? I'll try to diagram the two plumbing layout options in ASCII below (please ignore the periods; had to use them to keep proper spacing):

Option 1 (Single Mazzei Closed-Loop)

Intake 1>------\................................................. ./------->Return 1
........................>----Pump>----[Mazzei 584]----<
Intake 2>------/.................................................. \------->Return 2


Option 2 (Dual Mazzei Closed-Loop)

Intake 1>------\......................./----[Mazzei 384/584]------>Return 1
........................>----Pump----<
Intake 2>------/.......................\----[Mazzei 384/584]------>Return 2


If you've got any input or experience with Mazzeis I would love to hear what you think. Thanks guys!

You only need one for such a tiny tank.

They are really better suited for large systems, where such loss in head pressure is not going to make a big difference overall.

I'd chose option 1 personally.

I'd use a set of ball valves for each 1/2 line.

This way you can jam as much flow in each 1/2 line as you want. This will help with the dissolving of the CO2, you might not want as much mist, or only a light smattering of it.

Then the left over flow, out of the other side.

So this means adding the CO2 mazzei after the last Y.
Look, these things are very responsive!

Even one 1/2 mazzei with 300-400gph running through it should knock the pH down by a full unit inside 30 min in a 125 gal.

Maybe less time.

For smaller tanks, say less than 75 gal,l go with DIY versions of mazzei or inline diffuser disc etc.


Regards,
tom Barr

Thanks Tom. I really appreciate the input. I will stick with a single Mazzei.

After doing some more research on pumps I think I'm going to go with a Poseidon PS2 (~700 gph at a 3' head, 10-11 psi) and the Mazzei 584 (3/4") venturi. This should assure me of having enough pressure to adequately push the Mazzei and, if the flow is too strong, I can always throttle it. I'll post results when I get things up and running.

Just use at least 2 ball valves to throttle the loop effectively.

You should be able to dial in a good mist or a good dissolution depending on your preferences.

I generally will run mist durning the times I want optimal growth, then for viewing or pics, stop and reduce the amount of mist, wait 1-2 hrs, then snap the pic or invite folk's over.

That way the tank is optically clear and still growing like mad.

You really cannot do this with other methods.

Regards,
Tom Barr

Travis, I run a Poseidon pump on my 180g. Just a note that the Poseidon pumps do warm the water a few degrees, on the up side they are silent with no vibration.

I can attest to the quietness.
you can and should use some E6000 and a rubber based mat and this will quiet them even more. Iwaki's are pretty quiet and add no heat, and IME, last longer.
The Poseiden are smaller and shorter, so if you have limiting space, not a bad option.

Once inside the cabinet, you can dampen sound a fair amount.

I did find a really good supplier for these pumps:

Iwaki Pumps - External Water Pumps - Aquarium Supplies | Tropical Pet Fish Supplies | Aquariums

External Water Pumps - Aquarium Supplies | Tropical Pet Fish Supplies | Aquariums

Both are pretty good pricing for either pump.

Regards,
Tom Barr