How to calculate CO2?

[Lukara]

Hi, I was wondering if anybody here could tell me what the formula is to calculate my CO2 levels?

Thanks :)

[carpguy]

You just use this handy chart (http://www.sfbaaps.com/reference/table_01.shtml). Its not foolproof, but what is? The chart depends on you're buffering being from carbonates: in some unusual circumstances there may be other buffers, don't recall the details, but it effects the outcome. If your results don't make sense, post back and one of the more knowledgeable folk will help you sort it out.

[wetmanNY]

The buffer could be partly from phosphates. They're added to our New York City water: you may have them in your water too.

Borates would be a very unusual possibility. But someone-- maybe not here at AC-- dosing a planted tank and suffering inexplicable problems recently was dosing with boric acid!.

[Lukara]

OK, so let me see if I got this right....

I did tested my water today and my KH is 40 mg/L (divide by 17.8 to convert that to german degrees which gives 2.25) and my PH is 7.6. So if I used the table to see what the ~ CO2 level is, that would mean that my CO2 is approximately 1.7 mg/L?

Is the recommended dose of CO2 for a heavily planted tank 10-15 mg/L?

I ask because I'm having a case of algae (not severe yet) but I'm looking to see if I could get my plants to outcompete the algae and at this point I'm wondering if they're getting enough CO2...

Any help would be greatly appreciated!

[oyashare]

Here is an actual calculator.
http://watergardens.coolnessdojo.com/co2chart.php

Omid

[Lukara]

Thanks Oyashare. I used the chart and the result was 2.087. So... I from what I've been reading, this is fairly low.

Is the proper amount for a well planted 50 gallon tank 10 - 15 ppm?

[carpguy]

On the first chart, you want to be in that middle band for plants (14-30 ppm). The white area (where you are) is low for plants, the darker area is dangerous for fish. Ideally you'd want enough to get to the upper teens or into the 20 ppms. From what I've read, DIY will get you maybe as high as 20 (can add 10-15 ppm), pressurized is needed to maintain higher concentrations.

[Lukara]

Thanks so much for your replies. The help on this site is quite amazing.

When I originally posted this thread, my KH was 40ppm, PH was 7.6 which gave a CO2 result of approx 1.65 ppm. So I added some baking soda (2.3 tsp) to raise my KH to 90 ppm and increased my CO2 to release approx 1 bubble per 3 seconds. I'd like to achieve a PH of 7 - 7.2 and a CO2 level of about 15ppm.

Now, my question, how long does it take before the PH levels change from the increase in CO2 levels?