Advanced Reading on CO2

[Purrbox]

I'm currently using the followng formula to calculate CO2 levels, which is the same formula that most of the calculators use.
CO2 (in PPM) = 3 * dKH * 10^( 7-PH )

It came up in coversation in Chat awhile back that this is probably a very simple version of the calculation, and that there is actually a more complex (and more accurate) calculation for CO2. Does anyone happen to have the more complex calculation or information about it?

Thanks!

 

[malkore]

the only time I"ve seen anything more complex, was a 9 page discussion over at plantedtank.net

a couple chemistry guys figured it out. however, the above formula is accurate within 10%...and that's only because you're bound to have some buffering besides just Kh.

Even then, at 30ppm per the calculation, that means 27-33ppm...a perfectly fine range.

 

[Purrbox]

I tried searching for that thread on PlantedTank.net but obviously wasn't using the right search terms as I didn't find any discussions on CO2 that were over even two pages. It sounds like some interesting reading.

 

[czcz]

It came up in coversation in Chat awhile back that this is probably a very simple version of the calculation, and that there is actually a more complex (and more accurate) calculation for CO2. Does anyone happen to have the more complex calculation or information about it?

I do not know and have not read about this calculation, but remember that a more complex calculation will likely make more assumptions, including and probably not limited to test kit accuracy.

In the end experience trumps the formula, and more people seem to be opening up to the fact that they just crank CO2 and stop worrying about ppm. Just my observation, but I'm pretty sure people -- especially those that use EI principles -- have been doing this for years. Its just that now more people are talking about it.

If you suspect CO2 is too low, you probably need more

Just my two cents.

(And since iirc you are already on a staggered schedule with DIY CO2, its easy to add a new bottle to the schedule, so you can gradually increase CO2 while observing the animals.)

 

[malkore]

That's pretty much what I do czcz...maintain 30-35ppm of CO2 when the lights are on. I have 10dKh so it doesn't shift much at night.

A few people have told me that they've had good luck with glosso at just 2wpg, as long as they kept CO2 at 40ppm. nice horizontal growth, and pearling.

 

[Purrbox]

I routinely run my CO2 above 30ppm and have no issue with that. From what I've seen 30-60ppm seems like a nice safe range to help fight algae and not risking the fish health. I'm getting pretty close to finding the right generator bottle size and change out schedule to keep each of the tanks in that range.

It's not so much that I feel I need this more complex calculation to fix something in my tank, so much as I'm just curious about it and would like to find some more information. Guess I just miss those days when I was first reading about CO2 and felt like the information was going to make my head explode.

 

[czcz]

Yeah, suggest you move forward with another nutrient or look at alternate methods of transporting CO2, especially Barr's CO2 mist.

 

[newfound77951]

I've done the full calcs for seawater....they ain't fun....very complex, lots of assumptions, and a mess with units. If the above formula is good to within 10%, then I'd definitely go with it. For most of us with aquarium test kits, the accuracy of our kits is not high enough to gain any benefit from using the more complicated calcs.

FYI, the other factors besides pH and KH that make a big difference in the calc are salinity and temperature.

 

[Zezmo]

I crank my CO2 until my guppies start gasping, then turn it down just a little.

 

[Purrbox]

Well, after searching for awhile for the thread that Malkore mentioned I did find a couple of very interesting threads that relate to CO2 even if they don't relate to CO2 Calculations. The second two links are actually a discussion centering around Barr's CO2 Mist which czcz had suggested trying.

CO2 Saturation
CO2 Mist
CO2 Mist Part 2

~Edited to add extra CO2 Mist Link

 

[hashbaz]

It's not so much that I feel I need this more complex calculation to fix something in my tank, so much as I'm just curious about it and would like to find some more information. Guess I just miss those days when I was first reading about CO2 and felt like the information was going to make my head explode.

If you're like me you are a little dissapointed now that you know all the basics quite well. Learning new stuff takes a lot more work now that we know all the "easy" stuff.

 

[sherry]

czcz convinced me to try the mist and I am loving it. my plants pearl like mad and I got that ugly reactor out of my tank. If anyone wants a plantguild reactor let me know.

 

[Zezmo]

I use a mist too. On the main tank, the CO2 diffusor bubble right into the inlet of a powerhead. The plus side is it works awsome for the plants, the down side is now your tank is filled with a mist of fine bubbles.

 

[czcz]

To add 2 cents to Zezmo's post, I find the degree for that plus and minus for CO2 mist is so extreme it is interesting. Stuff like Eriocaulon and Tonina and R. wallichii -- hard plants -- just *love* it. If you want a tank thats always pretty, the bubbles will drive you crazy: mist plus pearling just looks like a swirl of bubbles. I've been considering putting my mist powerhead on a timer along with "noon burst" lighting to see what will happen, and limit the time I have to live with the CO2 bubbles.

Purrbox and hashbaz, if interested there's a bunch of "new" concepts linked here. The list grows when I'm not lazy.

Here's one where George Booth disses the whole "increasing CO2 when there's probems and the fish don't gasp" method: http://fins.actwin.com/aquatic-plants/month.200603/msg00076.html Always good to read alternating viewpoints from gurus

 

[7Enigma]

Just wanted to thank the OP and other poster's in this thread for the discussion. The links provided were very interesting!