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HELP needed What is max level of CO2?

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I am really needing help since I can’t find any good information on this. I have plants only aquarium and since I know that CO2 is good for plant growth I have arrived at this question:

What is the and maximum value of CO2 ppm that I can diffuse in the water to get very good effects?

And I mean here like maximum level for the best results and also the level when things might get bad as for the water turning too acidic.

From the information that I could find online it said that 30ppm is good because then it’s good both for plants and fish but since I don’t have any fish in my tank I was curious how much I can actually raise the CO2 ppm value.

I would be very thankful for any help!:laugh2:

Susan :)
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12,174 Posts
You could probably crank it to 40 or even 45 ppm.

There is a point though, where the amount of CO2 loss will offset the amount you're injecting though, and CO2 will only drop pH to a certain pH as well.

2,602 Posts
Of late, I've been dropping back from my ~40ppm area, not least of the reasons being that I now run it 24/7. However, my primary reason is to target what I believe is the pH 'sweet spot' for nutrient uptake by most plants. This seems to be in the pH 5.8-6.5 area. So, I watch my KH levels and adjust my CO2 accordingly. My plants grew fine at lower pH levels, but i'm in the fine-tuning stages of a year-long shift in overall strategy and don't believe the extra CO2 is helping anything..
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