High Efficiency Rex Griggs/ Cerges Reactor - The Planted Tank Forum
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post #1 of 4 (permalink) Old 10-27-2016, 07:54 PM Thread Starter
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High Efficiency Rex Griggs/ Cerges Reactor

Let me start off by saying this is purely an idea, that, depending on the feedback, I may build. Ok, so my idea is to build a cerges/ rex griggs style reactor that works similar to a calcium reactor in the reef world. If your not familiar with a calcium reactor I included a picture below.

By replacing the calcium reactor with a griggs/ cerges reactor, the water would circulate multiple times inside the reactor, thus saturating the water with co2. Now, obviously, the water would be returned to the tank at a higher rate than the drip of a calcium reactor, but as long as the turnover of the reactor system was faster than the rate of water pass through the system it theoretically would work.
Now the part I am unsure of is; how much higher would the turnover of the reactor have to be, than the water flowing from the tank through the system? Lets say that this is used on a 40b display tank, and you passed 40gph of water through the system. That way you turn the tank over once every hour, with the filtration and other forms of flow helping to distribute the water evenly over the tank. Would turning over the reactor at 200gph, so 5x faster, be enough to saturate the water? On the other end of the spectrum is 5x more than enough to saturate the water?
The efficiency of the reactor would have to be much greater than that of a griggs/ cerges reactor, to justify the added cost of the extra pump needed for the system. Does anyone know how much co2 can be dissolved into water and how much co2 a well built griggs/ cerges reactor can dissolve?
Any opinions are welcome. This was just an idea that popped into my head, and being the engineer that I am, I thought I would share and see what others thought.
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post #2 of 4 (permalink) Old 10-28-2016, 12:13 AM
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Myself I think that with a cerges or Griggs reactor, as long as you aren't getting bubbles in the tank you are getting close to 100% co2 absorption.
So the only way to make a reactor "more efficient" than 100% would be to build a reactor that is more free flowing than the cerges or Griggs style reactors. Looking at your idea and plans, it looks like it would be more work and take up a ton more space under the tank. But still is an interesting idea. For my co2 use I'm happy with no co2 bubbles in the tank, for me that's plenty efficient and much more simpler.


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post #3 of 4 (permalink) Old 10-28-2016, 01:49 PM
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think the system would work, but I don't think it would be more efficient than a properly build reactor
although you would be able to keep saturated water cycling through the reactor and only mix in "fresh" water when CO2 is required in the tank.
that way you could have a better and more precise control over the CO2

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post #4 of 4 (permalink) Old 10-29-2016, 04:15 PM
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When judging new design I often look at the cost versus benefit question. In this case we are looking at adding a good deal of complexity to the process and gaining only a little from the CO2 used. Since the CO2 loss is often due to gassing off, I'm not sure having "super saturated" water falling into the tank would reduce the loss or if more would be lost in the process.
But since CO2 gas is so cheap and equipment like pumps, so expensive, I would not think the payout point would be one that would attract me.
I would think a better, far less complex way to reduce cost would be to use a larger CO2 tank. The real expense of CO2 is not the gas itself, but the labor involved in filling the tank as well as the time and effort we spend going to/from to get the cylinder refilled and changed out.
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