# Understanding API gH and kH readings



## hisplaceresort1 (Mar 10, 2014)

Hello, all.
I don't have a problem(?), but do not understand my water hardness readings...

API Test Kit measuring general hardness and carbonate hardness... 
the results chart goes up to 12 drops, the equivalent of "degrees". dKH

The ppm of whatever they're measuring does _not _go up in a linear fashion.
http://www.apifishcare.com/pdf/GH_and_KH_Test_Kit_and_KH_Test_Kit_58-59_Insert-3.pdf

Over the last couple of months, my gH has been from 21 down to about 17. (It started lowering after I added driftwood). My tap water is about 19.
For kH, 17 to about 15 degrees after 7 days (measuring right before water change) Again, it started going lower after adding driftwood. It's about 17 out of the tap. My water is about 8.0 pH out of the tap. My tank has always been 8.2 and occasionally maybe 8.3. But pretty bulletproof steady.

I was once afraid to add aquarium salt because I was already literally "off the chart"... But apparently my water is pretty buffered, because it didn't change when I added it before. I don't add buffers. Just Seachem Prime as a water conditioner.

I actually know why my water is this hard... my municipality adds a lot of lime to keep it within state standards... cringe... and our rock beds are limestone... The river I live on has a limestone bed, and measures nearly the same.

So, my question is - do I have anything to worry about? I emailed API about how high is too high, and all they said was... "Great! your cichlids should love it." A condescending answer when what I wanted was to actually understand just what 21 drops and 19 drops actually measured!

But anyway... just wondering if anyone knows 1.) if this is a potential problem or not, and 2.) how high is too high and 3.) what do the drops actually correspond to?

Thanks!


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## Deeda (Oct 12, 2012)

1° = 17.9 ppm, it is just a conversion to another measurement.

So if your GH is 17 drops of API reagent before it changes from orange to green, this means you have 304.3 ppm of hardness, (17 x 17.9 = 304.3).

The same with the KH, 15 drops of API reagent before it changes from blue to yellow means you have 268.5 ppm of alkalinity.

Your hardness (GH) and alkalinity (KH) are just fine for the rift lake cichlids. I don't see any problems. A KH over 7° usually reduces the chances of pH problems.

Hopefully this answers your questions.


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## hisplaceresort1 (Mar 10, 2014)

it does... Thank you!


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