# CO2/KH-GH Chart????



## GIfishguy (May 6, 2008)

I am a little confused about the conversion chart. I have a 55Gal planted tank with tetras and rasbosas and some other fish in it. I've always had problems with my PH being low (6.0) because of low KH/GH (is about 1-2) I do not have CO2 injection. Can I still asume that the my CO2 levels are high? If the plants use the CO2 in my tank, wouldn't my PH go up?


----------



## Left C (Jun 14, 2005)

You said that you have a pH of 6.0. Is this measurement taken straight out of the tap? 

Pour some tap water into a cup and let it set out for 24 to 48 hours and measure you pH. It should measure between a pH of 7.0 to 7.3 with a KH of 1 to 2. This allows the water to degas itself and reach an equilibrium with the atmosphere.

If you aren't adding any CO2, you don't have anymore that what is available from the atmosphere or ~ 3 ppm.


----------



## GIfishguy (May 6, 2008)

My water comes out of the tap at 7.0. if I let it sit it will drop. My tank is 6.0. It has always done that with my tanks. I had to put some crush coral in my cichlid tank to keep it at about 7.0 with a GH/KH of about 4-5. 

So the chart only works if you are suplementing CO2?

Should I raise the PH before adding CO2 to the equation.


----------



## Left C (Jun 14, 2005)

Your pH should rise after you let the water sit out. It's impossible for the pH of the tap water to get lower with a KH of 1 or 2 after it sits out unless it is tampered with.

Try it sometime. Measure the pH of your water fresh out of the tap. Then let that same water sit for 24 to 48 hours and measure it again. You can stir it from time to time to help it to out-gas itself. You will find that the pH has actually risen.

I can understand about adding tap water to your aquarium and the pH falling. You probably have acids that are built up inside the aquarium. Some of these acids could be nitric acid, carbonic acid, tannic acid, sulfuric acid, etc.

It would be a good idea to go back and read what Chuck says about the pH/KH/CO2 relationship. If it's not really clear, go back and read it again. That's what I had to do. There's a ton of information packed into that article and sometimes it's hard to grasp all of it at one time.
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

You can use the calculator to play with some numbers using your KH of 1 to 2. You will find that you need a pH of 7.0 to 7.3 to equal a CO2 level of around 3 ppm.

My water has a KH similar to your water. I don't add anything to increase the KH. It's simply not needed. You are really blessed to have soft water. Ask some of the hard water guys sometime.

You may have to add a little GH Booster for the plants. They need the Ca, Mg, K and Mn in it. You may get by with just adding Epsom Salt for a little Mg increase.

The chart only works if the only buffer present is carbonate based. Most aquariums have phosphate that can buffer the water some. Other acids and bases in the aquarium can skew the results as well.

If you aren't adding any CO2 to the water, you won't have any more CO2 that what is available to it from the atmosphere. Whatever CO2 that the fish and critters add is only a very tiny amount.

A very good method to determine your CO2 level is in an aquarium is by using a drop checker/CO2 indicator with a known carbonate based dKH solution and a few drops of Bromothymol Blue pH indicator fluid.


----------



## GIfishguy (May 6, 2008)

Thanks for the info Left C. Ya I guess I am blessed to have soft water for my little guys. How do I bring the PH up to, and keep it there, without raising my KH? I guess I'm looking for that happy medium.


----------



## hoppycalif (Apr 7, 2005)

The best way to deal with the 6.0 pH is to ignore it. That is well within the range that plants do well will, and, for most fish it is no problem either. The fish you mentioned will do fine with that pH.


----------



## GIfishguy (May 6, 2008)

great! thought so but that makes me feel a little better at least.


----------



## Left C (Jun 14, 2005)

The folowing is to reinforce what hoppycalif mentioned. About a month ago, I set up a new aquarium with a dusting of peat moss and Eco-Complete. I believe that I added a bit too much peat because I have to drop the pH to the low 5's to get a green drop checker color using the 4 dKH solution. This aquarium has about 0 dKH instead of 1 or 2 dKH like the others. There's a school of Cardinal tetras, a breeding pair of dwarf cichlids, pygmy cories and otos. The fish are fine.


----------

