CO2 rate

PeterGwee

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Jan 23, 2005
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George Booth said:
1) Your CO2 "reactor" (whatever means you use to get CO2 mixed with the water)
is not very efficient. I forgot how large your tank is, but 2 bps does not sound
huge unless you have a very efficient reactor or a smallish tank. Don't forget
it will take more CO2 to raise the concentration initially than it will take to
maintain it.
This is one of the reasons it it not smart to turn CO2 off at
night.

I found a thread in APD that George Booth posted quite long ago regarding CO2 rates and CO2 level. I'll like to see the view of what folks here have to say regarding the line in bold.

Regards
Peter Gwee
 

detlef

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Jan 24, 2005
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Re: CO2 rate

Hi Peter,

regarding the often from Tom cited paper (Bowes et al. 1976) C02 levels in the early hrs into the photoperiod seems to be the most important.
Quote: "Most photosythetic activity occurred in the morning when the free CO2 was highest and O2 and solar radiation was lowest."

Thus, CO2 injection should arrive at 30ppm when the lights come on as I understand it. Nothing new here Tom repeats keeping CO2 levels high during the whole photoperiod for years. I bet that even Amano does not arrive at 30ppm with lights on since he switches CO2 and lights at the same time.

I found I had to start injection 2 to 2,5 hrs before lights come on as to arrive at the targeted level. I'm using an Aquili diffusor which is similar to Amanos' which I was using before also. One minor drawback is a high CO2 spike (around 50ppm) in the afternoon. Fauna does not seem to be affected though. Recently I started to fight the spike with additional O2 bubbling. I don't know yet the side effects.

Regards,
Detlef
 

Tom Barr

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Jan 23, 2005
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Re: CO2 rate

Many blast the lights during what time? Midday after the CO2 has had a chance to build up.

Amano does that.

You can simply add CO2 1 hour prior to the lights on phase if response times are an issue, there's no drain on the CO2 and there's a fair amount by the time the lights come on.

Shut the CO2 off 1 hour before the lights go out.
Amano does that too.

Not an issue, I disagree with GB about the CO2 though, I think the tank does better without adding it at night, so do fish.

GB whines about the high CO2 and then exposes the fish to chronic 24/7 high levels, I'm not sure why that makes sense but what I suggest does not:)

We add CO2 for the plants and do not add too much to hurt fish, clearly CO2 at night holds no good purpose for the fish, the notion that pH stability is of any consequence is ludicrious, we do large water changes each week and observe no ill effects and the changes are rapid and dramatic with CO2/pH.

No issues there.


Regards,
Tom Barr
 

PeterGwee

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Re: CO2 rate

I can get the CO2 mist to move around the entire tank (20 gallon long) pretty effectively for my method but I just couldn't get 30ppm within one hour along with the lights as Tom often mentioned unless I crank the rate higher but it will hit excess and perharps toxic range late in the day. I really am not sure what is missing since the CO2 is moving around good and Tom just say in his pm to me that he gets the response time of 1 hr for his 20 gallon tank. :confused:

I'm hoping for diagrams and detail illustrations from him since I feel alot of folks out there still have this issue.

Regards
Peter Gwee
 

PeterGwee

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Re: CO2 rate

detlef said:
I found I had to start injection 2 to 2,5 hrs before lights come on as to arrive at the targeted level. I'm using an Aquili diffusor which is similar to Amanos' which I was using before also. One minor drawback is a high CO2 spike (around 50ppm) in the afternoon. Fauna does not seem to be affected though. Recently I started to fight the spike with additional O2 bubbling. I don't know yet the side effects.

I'm not really into starting it early as the solution might work for a week but then how about the CO2 level after the weekly large water changes? Wait for a few more hours before the lights are allow to come on? :rolleyes:

Regards
Peter Gwee
 

Tom Barr

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Re: CO2 rate

There are a few ways to get things cooking.

1.Less light in the start up phase, 1.5-2w/gal
2. Add CO2 on another timer, starting 1/2- to 1 hour prior to lights on.
3. More current(unless maxed out already)/mixing
4. Less plant biomass(eg low growing HC mostly)
5. Distribution and flow pattern adjustments

Even if you max out all these, 15ppm at the one hour mark start, then gradually up to 30ppm at 2-3 hours is likely fine.

Main thing is to prevent CO2 limiting conditions. There are a few ways to do that.

I think mist method is one such method.
I see large growth rates eariler in the day using that method with similar or even lower CO2 ppm in the water.

This was confirmed by measuring the DO levels.

The plants, more so than the CO2 ppm, is the main focus.
The CO2 maybe a secondary effect, even if the CO2 is only 10ppm dissolved, how much is getting to the weeds that first 1-2 hours as mist?

I do not know, but I do know the O2 levels rise much faster.
So something is occuring, whether folks believe my notions or not I really no longer care.

Same thing with the venturi mist internal reactors.
You can max those out early in the day and then back off the flow(DIY can even be used in conjunction with gas tanks or a dual solenoid/valve to add more CO2 during the initial 1-2 hour phase).

Regards,
Tom Barr




Regards,
Tom Barr