Are my assumptions correct about my reactor?

[Progen]

So what I have modified slightly is to drill a hole and silicone a metal air stopvalve into the cap of a Jaqno prefilter (that's what the box called it). Then I've siliconed two pieces from other filters to get the water to hit the sides of the canister for better dissolution of the gas. I know it'll be better if I can attach another elbow to get the water to swirl but right now, there are no bubbles in the tank so I'm quite happy with it.

Now I'm not Mr Physics so what I'd like to know is this.

There's always some gas trapped in the upper part of the canister even when the CO2 valve is closed for the night. I've done experiments when I've flooded half the canister (rated at 1.5 litres) with CO2 and other than those trapped in the pocket, the gas was gone in about 12 - 15 minutes.

So what I'm assuming is that when flooded, the gas is under higher pressure which is why it dissolves faster and as the water level rises, the pressure of the gas drops until it reaches a point where the water movement / pressure is insufficient to compel dissolution.

Now I'm pretty sure that all of the gas inside is CO2 because I've inverted the canister to get all the air out at the beginning and no air's going into or out of the canister filter which is driving this reactor.

I was thinking of modifying it further with a T junction but since there's no gas buildup other than that pocket and no bubbles in the output, I left it alone.

 

[Progen]

Oh dear! This is my first post and I thought the forum script would have some kind of image resizing so if folks are seeing it as large as I am, please accept my apologies.

 

[Radical MT]

What is the question exactly?


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[Progen]

What is the question exactly?


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The highlighted part. Am I right to assume that when the valve's off, there's always a bit of CO2 trapped above because the conditions are inadequate to get that bit of gas to dissolve.

 

[Radical MT]

What I can suggest is for you to try an U shape inside the serger to move the gas on top around and to have a better dissolve.


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[ian_m]

Often the gas collecting "stuck" inside peoples DIY reactors is in fact nitrogen and/or oxygen coming out of solution from the tank water rather than excess CO2. You need to devise someway of allowing it to escape and/or be flushed away.

Some people have great success by making the water vortex round in their reactors which will generally flush away any trapped air/CO2.

 

[Progen]

Often the gas collecting "stuck" inside peoples DIY reactors is in fact nitrogen and/or oxygen coming out of solution from the tank water rather than excess CO2. You need to devise someway of allowing it to escape and/or be flushed away.

That gives me an idea. Just for the fun of it, I'll siphon a bit of that gas and test whether it's combustible.

 

[Radical MT]

That gives me an idea. Just for the fun of it, I'll siphon a bit of that gas and test whether it's combustible.

I think Tom Barr did a test on that. Look for his forum. The Barr report


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[Progen]

What I can suggest is for you to try an U shape inside the serger to move the gas on top around and to have a better dissolve.


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The thing is mine isn't a Cerges. It's much simpler and seems to get the job done with zero noise. In fact, there are no bubbles inside the reactor too.

What I assume to be happening is that the gas pressure builds up to a point where it is forced to dissolve into the water. There is definitely some pressure buildup caused by the incoming water as well or else it'd just come in from the top and out through the bottom without ever filling the canister.

Now these are only my assumptions which is why I'm asking whether I'm right.

 

[Progen]

I've come to the conclusion that this method is no less than the Cerges or Griggs and a tonne less complicated.

It works on the gas building up pressure in the canister to a point where it's forced to dissolve into the water. Same end result, less work. No additional powerhead needed.

In this version, I've added in filter media for the sake of extra biofiltration and it's without the elbow to direct water to the side to create turbulence.

I've also placed the canister on its side with the outflow pointed diagonally downwards. No spray bar attached so the inflow is equal to the outflow with less resistance and a quieter impeller.

The diffuser was stuck there as a marker of the level when using a 2bps rate vs a crazy uncountable rate for 45 minutes to get a rough idea of how high a gas flowrate would result in the water being driven down to a level where gas would then enter the outflow. Guess it'd take full blast to do that so there's nothing to worry about even if I don't turn off the CO2 (which I do every early evening) for a few months.