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[APD] Radical thoughts on DIY CO2 reactor designs

I've been secretly doing some test using a DO meter, chamber tubes and an IR to see about gas build up and efficieny of CO2 reactors. Perhaps not radical, but few have really looked at this issue in this much detail.

O2 levels are directly correlated and proprotional to gas bubble build in CO2 reactors, wereas the CO2 levels are not. 

In testing this idea, I needed to maintain the CO2 level. This was a problem since at higher levels with plants, the O2 levels exceeded saturation and outgassed in the chambers.

We have all seen this gas build up occur diurnally as the photoperoid progresses throughout the day. Many folks have asked why this occurs. Well, rather than sitting around wondering...........

This off gassing of O2 greatly reduces the efficiency of a CO2 reactor when you need it most, near the last half of the day.

After about 4-6 hours of intense lighting, the O2 levels are sky high.
I measured the gas build up (In millimeters) in the reactor tube and graphed it next to the O2 levels(ppm).
Next, I did the same for CO2. CO2 went down while the O2 continued to match the reactor tube level. 
I tried my internal designs and they did super though. the O2 levels rose, but so did the CO2 levels.


The venturi loop I added to my old design some 10 years ago.
This is the same venturi loop I have on the DIY internal Reactor here:


At first glance, the venturi appears to waste CO2, but it's really there to pruge O2.
This pruging allows the reactor to operate at a higher efficiency dissolving CO2. 
Some folks asked why I added that. Now you have the reason, I needed to prove it first though. 

Internal reactors have little issues with gas lock and flow reductions. 
I have recently designed a DIY External reactor that pruges the O2 in a similar manner.
This removes the gas lock and O2 build up automatically and gets back to the business of dissolving CO2 when you need it, during the day.

An interesting note: the Sintered diffuser stones do not have this O2 build up, nor does the internal DIY reactors I've posted plans for. So that is one good thing about the snintered stone diffusers, all the gas is CO2 coming out of them. There are trade offs with them also(Clogging and maintenance, good flow is needed to to diffuse through the larger tank sizes and other issues). FYI, if folks are interested, I know a company that also sells 1"x6" stones much like the airstones but at 100-500micron bubble sizing for around 55$. I am not affliated with the company nor do I sell these. This size of stone would be enough for a 200 gal tank or so. Unlike the ADA products, these can be placed on the substrate or under wood etc hidden from view rather than on a side or back glass pane. 

I'll post a DIY externals venturi loop design in a few days. These will give the best response of any reactor designs for our needs and also be cheaper than any commercial products internal or external.

Tom Barr




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