CO2 Chart - Page 4 - The Planted Tank Forum
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post #46 of 57 (permalink) Old 12-04-2011, 05:52 PM
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Posts: 4 ph is 6.1....and mydkh is 1...ppm gh/kh is 17.9...with out co2 injection? question is my tank getting co2 from elsewhere?
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post #47 of 57 (permalink) Old 04-14-2012, 03:10 AM
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oOKkay...This way is much clearer:
dKH = 1
dGH = 17.9
pH = 6.1

It will help if you provide more info on plants, tank size, lights, trying DIY CO2? etc.

If lights are strong enough plants' chloroplasts are able to make plant sugar/energy from carbon in solution (depending on plant requirements this translates to having preferably higher alkanity).

Floating plants are able to get their energy from carbon dioxide in air but also benefit from carbon in solution as carbonates, organic soil, etc
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post #48 of 57 (permalink) Old 07-07-2012, 12:09 AM
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How would you use this chart if your PH is past 8.2? Or better yet keeping your PH at 8.2 while maintaining adequate PH. I have hard water cichlids (lake Tanganyika), but am planning on planting the tank. Is there no way to keep the KH/GH at 8-15, PH at 8.1-8.3 and still maintain decent levels of CO2 with very little swings in chemistry?
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post #49 of 57 (permalink) Old 10-16-2013, 04:56 PM
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Interesting reading through the learning curve. Figured out my problem. That chart is the Bible. The harder the water the less CO2 it takes to get to 30 ppm. I am at 11.5 Kh according to Salifert so my range is 7.2 Ph. I was cooking my plants with CO2.
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post #50 of 57 (permalink) Old 03-05-2014, 03:46 PM
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I have just read this whole thread. Great information BTW!

I would like to see the article and chart but the link is broken.

It appears to me some people keep referecing the pH of their aquarium water when actually the chart is for a drop checker REFERENCE SOLUTION as others have stated. Unless of course your tank water has few or no other acids in it... Is that correct?

My QUESTION is why at the base of the chart does it say the ideal CO2 is 25ppm when most people are targeting 30ppm or even higher as Tom Barr has stated? It clearly says that anything over 25ppm is dangerous for livestock. Is this true or not?


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Last edited by kirk; 03-05-2014 at 03:57 PM. Reason: to try and be more clear
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post #51 of 57 (permalink) Old 03-05-2014, 04:32 PM
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Optimal CO2 is based on the individual aquarium in question.

A low light tanks with a shop light over it, maybe 1-2 bulbs, well, the CO2 demand is not going to be great.

A similar tank with more light that's strongly PO4 limited, will also have less CO2 demand.

A very high light tank and plenty of ferts, and also very intense plant growth, will need more CO2.

So there's no one single optima for all tanks.

For most densely planted moderate light tanks with reasonable ferts, 30 ppm is a good target to start with. But the chart may not be accurate due to the tap water treatment for SOME tap water suppliers, while it's likely okay for others.

Optimal CO2 is pretty much done by eyeballing it. Looking at the plants, growth and fish/livestock health.

You get close with measurements as best you can, then the rest is a slow progressive increase/decrease and watch closely over the next few days before deciding to add more/less etc. There's no hard no# associated with CO2 really. And it's not something you can easily measure and dial in. You need to work at it.

You need to know the signs of poor CO2, in plants, in algae and with livestock.

Unfortunately, this means experience. Which newbies and folks with issues rarely have .

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post #52 of 57 (permalink) Old 03-15-2014, 05:14 PM
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Originally Posted by Loligo View Post
Whew! I wish the first post of this thread said, "For use with a standard dKH solution. Compare the color of your drop checker to your pH test kit card, and use that reading (along with your standard dKH) to find your ppm of CO2." that's here in case someone as slow as me reads this.
Thanks! I too was using the pH reading of my tank water instead of the drop checker. Proper instructions should be printed in bold letters right on the chart itself. After you've been in the habit of checking the pH of tank water for years, and then you see a chart that requires you to take a pH reading, how are you supposed to just automatically know that it's a pH reading of a drop checker, not a pH reading of tank water like you've been accustomed to doing all those years?! Maybe some people are just born knowing this stuff, but not me.

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post #53 of 57 (permalink) Old 03-18-2014, 01:54 AM
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Dingdingding! I finally got it!

My drop checker didn't come with a full chart, just "blue is low, green is good, yellow is high" but I can use the chart that came with my API freshwater kit to get the pH of the dropchecker solution. So from the CO2 chart, I am closer to optimal CO2 than I thought (ignoring the presence of other buffers), which supports my hypothesis that I've been neglecting some other fert all this time.

DC pH = 7.2
tank KH = 5
GH = 6-7
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post #54 of 57 (permalink) Old 03-18-2014, 02:10 AM
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Soo... If the "appropriate" CO2 level is dictated partially by the CO3^(2-) KH level... THEN I should be able to dose baking soda again, get another degree of KH and then the levels of CO2 in the tank will be even better for my plants? I had added baking soda to my tank last week to raise the KH one degree after reading about it in Walsted's book......... Without an effect on the pH, which was my main concern...

I know someone said earlier that the CO2 produced by the fish should be negligible, but I have 10 goldfish in 100G here. I want to turn the airstone off but I am scared of oxygen deprivation, especially with my old one. Are there differences between how the fish act with oxygen deprivation and carbon dioxide overkill?

Is there a danger in raising CO2 concentrations if I don't really have the plant load, or is it more of a concentration thing rather than a total CO2 in the tank?
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post #55 of 57 (permalink) Old 02-05-2015, 01:10 AM
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once you have timed your gh and kh times that by 0.056 to get the number for the co2 chart.
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post #56 of 57 (permalink) Old 02-05-2015, 02:39 AM
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Equation to solve for chart.
If KH or pH is out of the ranges in chart.

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Growing is not that difficult.
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post #57 of 57 (permalink) Old 12-25-2018, 01:35 AM
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