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GDominy 02-04-2005 10:38 PM

CO2 Chart
1 Attachment(s)
For quick and easy reference, here is a copy of Chucks CO2 Chart, easy to read.

Original Information credited to Chuck Gadd. Chart values used from:

masYPSI 11-15-2006 03:49 AM

How do you convert from degs, on the chart, to ppm, what i have.

Lycosa 11-15-2006 03:53 AM

Divide ppm by 17.8 to get degrees.

west9491 01-04-2007 01:28 AM

you don't have to convert, skip the degrees part. Type in your pH, then skip the degrees box, type in your KH reading ppm in the box to the right. Then when you click on the degrees box, your reading of both your co2 concentration and KH reading converted to degrees should show, pretty neat, took me a while to fig. out.

but i'm running 16.6 w/ DIY co2, i have the stuff for a co 2 tank, just can't find a co2 tank that is ridiculously priced, any suggestions?

cbennett 01-04-2007 05:57 PM

just a note: most KH test kits give results in "mg/L" - that is the same as ppm.

leoslizards 02-07-2007 01:20 PM


Originally Posted by cbennett (Post 352577)
just a note: most KH test kits give results in "mg/L" - that is the same as ppm.

Yeah I was wondering the same thing. This has been very confusing to me. My test kit also give results in "mg/L" and I don't know how to measure that in ppm. For example my test kit says to add one drop of solution at a time until it turns a certain color and take the number of solution drops added and multiply it by 20 for GH and 10 for KH. My tests resulted in 11 drops of GH solution and 11 drops of KH solution, which I then multiplied.

11x20=220 GH
11x10=110 KH

The chart only goes to 15 KH Can someone please explain this to me? Thanks. :)

Hoppy 02-07-2007 05:50 PM

The chart is based on degrees KH, not KH in ppm or mg/liter. The conversion factor is 17.86 ppm per dKH. Your 110 KH = 6 dKH.

IceH2O 02-07-2007 06:19 PM

Goes to show these charts and caculators are worthless.

I don't inject CO2, I use Excel which won't translate into a CO2 reading.

According to the chart my CO2 level is almost 38 ppm.

We all know thats impossible. Most I could have is whats in the atmosphere, what is it 3-4 ppm?

Hoppy 02-07-2007 06:50 PM

The charts and calculators are not at all worthless. They are very good, but not for determining from the tank water KH and pH what the CO2 concentration is. If you use a drop checker, with distilled water having a known KH in it, the chart and calculator work extremely well. If you read carefully, Chuck Gadd notes in his discussion that the equation is not valid for water that isn't "perfect".

Glouglou 05-14-2007 11:28 PM

Itís for that some people prefer to use a drop checker solution, where you mix ph reagent and distill water that you bring to 4 or 5 dkh.

This way, no more guess...

4 dkh green at 30 ppm CO2
5 dkh green at 40 ppm CO2


plantbrain 05-15-2007 01:35 AM

Oh, there is certainly guessing, but it's trying to figure out how long the reaction time and what color is what in the drop checker.

Still, vast improvement over other methods folks had been using and assuming about KH.

Tom Barr

BlueRam 05-15-2007 03:49 PM


Originally Posted by IceH2O (Post 370332)
We all know thats impossible. Most I could have is whats in the atmosphere, what is it 3-4 ppm?

Atmosphere ~ 300 ppm (0.3%)
Water at equilibrium ~2-5 ppm.

Darth Sensei 05-17-2007 12:19 PM

According to that chart, my baseline CO2 levels are only 1.8. Is that possible?

My pH is 8.0 right now and 6 degrees KH.

IF this is correct, what ph should I shoot for? My calculation shows 6.8.

PLease help.

Rex Grigg 05-17-2007 12:33 PM

That is possible.

And you should shoot for a a drop in pH of one degree. So 6.8-7.0 is correct.

Steve Z 08-07-2007 02:18 AM

What does the Kh mean on Chuck's chart

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