KH and non bicarb alkalinity KH

Tom Barr

Staff member
Jan 23, 2005
Here is a good discussion on alkalinity and various methods used(eg by our cheesy test kits):

Given the precision with the pH measurements and pH monitors etc, seems this might be a better place to look when dealing with KH and ultimately CO2 determination for folks.

Give it a read and consider the methods and then consider your situation.
Many folks have very high theoretical CO2 levels but healthy fish and good growth while many have normal CO2 theoretical measurements and good growth/fish health as well.

What we do NOT see is low theoretical CO2 levels and indications that we have lots of CO2 in solution.

So the error almost always means we have __too little__, not too much CO2 in our tanks.
I've yet to observe too much CO2 from the theoretical measurement.

If you use 100% RO and reconsitute, you get around many of these issues, but then you have the trade off for cost of the RO, use and hassle.

Using both RO/DI and tap can tell you much more.
So you do not need to do the RO thing all the time, just perhaps 1-2 x and see(even a small test cup etc) and then set your tank with tap from then on.

These are practial things aquarist can do to figure out some of these issues like "Why do I have 79ppm of CO2 and my fish are fine?".

Tom Barr