With the test kit I purchased is a chart for CO2. No other information came with this chart. I am wondering what is the importance of CO2 and what does it mean.
The chart crosses KH and PH. It give me a number... what does this number mean and what if this number is not with in the parameters set by the graph?
Rae

Living things (fish, plants, algae, ec.) will produce carbon dioxide by respiration. Plants will produce oxygen during the daylight hours, but at night, they, too, will produce carbon dioxide. This carbon dioxide readily converts to carbonic acid in water - and this can lower your pH. Too much carbon dioxide (carbonic acid)with little or no surface/gas exchange can significantly affect your pH levels.

Just the opposite is also a fact - substantially increasing your surface area and air bubblers so that there is a maximizing effect on the removal of the carbon dioxide can potentially raise your pH.

Unless your tank is very heavily planted or populated, or unless you have very little gas exchange/surface area, this is not a very important factor to be concerned about.

A normal amount of air exchange, air stones and a good filter with a spill over or spray bar will quickly negate any problems or changes that carbon dioxide might produce.

CO2 (carbon dioxide) is used in planted aquariums, as most feel it's absolutely vital for plant growth. Here is an example of equipment used for adding CO2. The main things the equipment does is produce the gas, then dissolve the gas in the water, then inject it into the tank. Some people use yeast, sugar, and water to produce the CO2 gas, some buy it in tanks, then use the equipment to add it.

The test is important because adding CO2 to the tank lowers the pH. You don't want to add too much, because you will make the water too acidic. Some of the most expensive equipment is completely automatic, which uses a tank, a "reactor" which dissolves the CO2 gas into the water, and an electronic pH monitor so that it turns off the CO2 when pH drops too low.

I have plants but don't use CO2, I use an alternative product called Flourish Excel. Plants don't really want CO2, what they want is the carbon, and they get it from the CO2. Excel is carbon that is in a molecular form that plants (in theory) produce when they use CO2. I have found that it can sustain some plants and provide growth, but not as good as CO2. The reason I don't use CO2 is because I don't have enough room in my tank for the equipment.

Thank you for the information. It was easy to understand and very informative. Some times since I bought my aquarium I feel like I should take a chemisty class or two.
This website has been better than any class I could have taken.
Sincerely,
Rae

lol dont i know it! lol good thing i got top marks in chem

carbon diaoxide will produce carbonate acid.. and carbon dioxide decreases the the amount of dissolved oxygen in the tank too..

both are deadly and thus best to know how much carbon dioxide is present in the tank..

to remove excessive carbon dioxide, improve air circulation.. adding air stone, introduce water falls or anything that will stir up water surface and introduce bubbles into the water..

introduce plants and lighting is a good choice too.. though plants produces carbon dioxide in the night.. thus it is advisable to leave tank light on for 10 -12 hours a day..

cheers