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Discussion Starter #1
i drew a picture so i dont have to explain lol.



questions will the venturi work?
will i need to add a power head or should i plumb the venturi into my other filter inlet?
or leave it like it is? :-k

Parts list:
1 pvc 4 way 2"
4 pvc reducer to 1/2" npt
2 3/32" x 1/2"npt venturi fittings
2 5/8" x 1/2"npt fittings
1 3/32" x 1/2"npt
1 2" union for cleaning.
1 12" clear pvc
1 2" sleeve

my venturi fitting :cool:
 

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Hmmm... Not sure if I follow. Could you add a few more arrows for the idiots in the class (me)?
What does the yellow line represent? Is that some sort of closed loop system? The water flow in the upper right tube flows toward the 4way, would this cause a flow issue with the CO2 coming the other direction and meeting the water head on? Also does this sit outside or inside the tank...?
Just looking at it, I'd have to guess that you'd need some way of either drawing or pushing water thru that venturi under pressure. Not an expert, but I don't know if hooking straight to the filter inlet would acheive this. Looking at the inline reactor featured in that other thread, the water is forced thru the unit, drawing the CO2 with it...

Sorry, no help at all, I know. Best of luck!!:D
 

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Oregon, I'm a little confused too. Why are there two venturi fittings? Also I think you will have to very careful with obstruction of flow in this set up. If I am correct then the outlet and inlet of the DIY venturi seems to be about 1/4 inch. Seems very small to me and you could burn out your pump motor with that kind of pressure. Seems like the only venturi necessary is the one at the 4 way PVC fitting. The only problem with that is that depending on the efficiency of the venturi action you will have a steady stream of small bubbles going into your filter instead of staying in the reactor.

Don't know if I've got it right but that's what I can see from here.
 

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This idea will work, except that the venturi in the top of the reactor doesn't do anything, and the device shown in the photo of a "venturi" won't work. It won't work because as jmontee said, it places too much of a restriction in the water flow hose. It also won't work because it doesn't do what a venturi is supposed to do. A venturi, shown in the sketch below, speeds up the water flow through a throat, which causes the pressure of the water to drop, which sucks in CO2 where it is ripped into small bubbles by the speeded up water flow through the venturi throat. If the water hose is 5/8 inch inside diameter, the venturi throat should be something like 3/8 to 1/2 inch inside diameter. That wouldn't restrict the water flow much if the tapered inlet and outlet in the venturi were smooth enough, with no sharp corners anywhere.

The way this would work is that the CO2 injected at the top of the reactor would form a large bubble there, with some of it dissolving into the water. Some of it would be sucked into the venturi where it would be ripped into tiny bubbles and partly dissolved into the water. The rest would add to the big bubble at the top of the reactor, to be sucked back to the venturi for another trip through the water. If everything is sized right, you would get 100% of the CO2 dissolved into the water.

 

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Discussion Starter #5
lol ok


my hopes where one water entering the reactor would push agianst the co2 coming out of yellow line, this causeing co2 to stay in longer

2 that the water passing buy my "home made venturi" would create a siphion, their by sucking any water or co2 bubble thru a 3/32" hose to the reactor again.

3 that the change of pressure of the siphon 3/32" to hose 5/8" would be a venturi lol

4 my "venturi fitting" is actually just a 3/32" pvc type fitting to get co2 into the reactor i dont want to use brass.

5 the more i thought about this last night when I SHOULD HAVE BEEN SLEEPING the more i didnt like it because of the 90deg inlet

new way? 3 way pvc not 4. i was thinking inlet at top co2 on left, i have had trouble figuring out tom barr's design. what i am confused about is his "venturi" i will have to stick with his. learn by doing.

i wish i had the money i would just get one of those mazzi ones.
 

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Tom Barr's design isn't really a venturi based design. Any time the diameter the flow goes thru is reduced, the flow velocity goes up and the pressure goes down. So, just putting a fitting in the inlet line to the reactor you show, with the fitting having a somewhat smaller diameter than the hose, and with a hole in the side of that fitting with the CO2 feedback hose forced into it will act as a usable venturi. To avoid leaks a small barb for the CO2 hose there is better than forcing the tube into a hole, in my opinion. Then slightly melting the end of that barb, the end that goes into the tee, will give smaller bubbles there. My preference is to introduce the CO2 in the reactor further down the reactor, so the rising bubbles get exposed to more water. The flow velocity in that reactor tube isn't great enough to blow the bubbles out the bottom water outlet unless the bubbles are very tiny.
 

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My thought when I saw the drawing, overall, not exact materials list, was that larger CO2 bubbles would keep circulating in the yellow part until they were small enough to get dissolved in the incoming water (incoming from the right side or the drawing), and would get sent to the tank via the downward aimed outlet. I have seen such an item, but if I remember correctly there was a powerhead or a pump with threaded inlet and outlet where the 4-way PVC is in this drawing.
 

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Discussion Starter #8
I was trying to reinvent the wheel.

Really i like the tom barr design but i have never been much for drilling and gluing i prefer using fittings.
 

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I think we are trying to over complicate a simple piece of equipment, kind of a Rube Goldberg approach to a co2 reactor. If you check out the DIY co2 reactor thread in the DIY section, there are several simple yet very effective designs. A reactor works simply by keeping the co2 suspended in the water column until it dissolves, no venturi needed.
Brian
 

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Discussion Starter #10
LOL yes i have never been one to go with K.I.S.S. right off the bat!

i decided to go with a basic design. i will worry about the other stuff if it happens. only difference is i will add the union in it so i can separate the 2 pieces for cleaning.
 
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