API GH & KH Test Kit ? - The Planted Tank Forum
Old 10-08-2014, 06:15 PM Thread Starter
Algae Grower

Join Date: Oct 2009
Location: Marysville CA
Posts: 30
API GH & KH Test Kit ?

I'm having trouble understanding the conversion chart. The first column is # of drops, the second column is degree dkh and the third column is ppm GH/KH. The second column always corresponds to the first column. Once I obtain a test for KH and another test for GH I'm not sure how to read the chart. My KH reads 13 and my GH reads 16. I have extrapolated out the numbers so my chart goes up this high but I'm not sure what my readings are. Can somebody explain it to me?
ellio is offline

Old 10-08-2014, 07:50 PM
Planted Tank Enthusiast

Join Date: Jun 2014
Location: Florida
Posts: 767
I wouldn't worry too much about the ppm so long as you know your dKH and dGH. For reference though, you can multiply 17.86 by your degree reading to find out the ppm.

For example: When testing my KH, it took 12 drops to change the color of the solution. This puts my dKH at 12, or 214.32 ppm. Same with GH... 12 drops so my dGH is 12, or 214.32 ppm.
StrangeDejavu is offline
Old 10-08-2014, 10:38 PM
Planted Tank Guru

Join Date: Jun 2012
Location: Gainesville, FL
Posts: 2,105
The number of drops are the degrees of hardness (dKH and dGH...the d denotes degrees). As StrangeDejavu pointed out, to convert to ppm just multiply by 17.86. All the math and chemistry aside your numbers simply mean you have hard water.
Zorfox is offline

Old 10-08-2014, 11:56 PM Thread Starter
Algae Grower

Join Date: Oct 2009
Location: Marysville CA
Posts: 30
Quote:
Originally Posted by StrangeDejavu View Post
I wouldn't worry too much about the ppm so long as you know your dKH and dGH. For reference though, you can multiply 17.86 by your degree reading to find out the ppm.

For example: When testing my KH, it took 12 drops to change the color of the solution. This puts my dKH at 12, or 214.32 ppm. Same with GH... 12 drops so my dGH is 12, or 214.32 ppm.
Quote:
Originally Posted by Zorfox View Post
The number of drops are the degrees of hardness (dKH and dGH...the d denotes degrees). As StrangeDejavu pointed out, to convert to ppm just multiply by 17.86. All the math and chemistry aside your numbers simply mean you have hard water.
Thank you so much, both of you.
ellio is offline
Old 10-09-2014, 12:44 AM
Algae Grower

Join Date: Mar 2014
Location: MN, USA
Posts: 129
GH is General Hardness, roughly the amount of calcium and magnesium in your water. GH is what we talk about with hard water; spotting, hard to make suds. GH is important to fish mineral transport via. osmosis and plant growth.

KH is carbonate hardness, the amount, again roughly, of carbonates and bicarbonates in your water. KH is sometimes called alkalinity or buffering capacity of water. It represents the ability of your water to maintain pH by reacting with acids in the tank. Ammonia generation from fish respiration and decomposition of organics is eliminated from a tank mainly by the biobacteria or biofilter with nitric and other acids as metabolites. In water with very low or no KH (rare with tap), pH can drop over time and cause the biofilter to slow ammonia removal dramatically and result in high ammonia. The pH drop is sometimes called a crash and typically is avoided by regular pwc's.

Some plants have the ability to extract carbon from carbonates, also.

With the usual buffers in tap to prevent corrosion or metal leaching, as KH increases, pH does also.
Bloomer is offline

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