Unit of Measurement for GH and KH - The Planted Tank Forum
 1Likes
  • 2 Post By Hoppy
 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 02-09-2016, 11:11 PM Thread Starter
Planted Member
 
Iwagumist's Avatar
 
PTrader: (0/0%)
Join Date: Jan 2016
Posts: 184
Unit of Measurement for GH and KH

I use the API liquid test kit to measure my KH and GH, and I am really confused . In the back of the instructions is a conversion chart for the test readings, and it has two different units of measurement: dKH and ppm. So, does dKH measure KH and GH or just KH? Also what degree is considered hard and what soft in a planted tank? My KH is reading about 8 dKH (143.2 ppm) and the GH is 9 dKH (if you can use that unit for GH) or 161.1 ppm. Is that really hard? Any advice is welcome !
Iwagumist is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 02-09-2016, 11:27 PM
Planted Tank Enthusiast
 
PTrader: (0/0%)
Join Date: Apr 2015
Location: Queensland
Posts: 525
Degrees and ppm is exactly the same as metric and imperial, they both measure exactly the same thing.

KH is KH, and GH is GH. Doesn't matter what scale they're being measured in, degrees or ppm. One degree of general hardness (dGH) equals 17.848 ppm of general hardness (GH). One degree of karbonate hardness (dKH) equals 17.848 ppm of karbonate hardness (KH).

https://en.wikipedia.org/wiki/Hard_w...classification
Note that this applies only to the GH measurement of the water.

Feel free to edit.
Audionut is offline  
post #3 of 6 (permalink) Old 02-10-2016, 01:16 AM
Planted Tank Guru
 
PTrader: (84/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,015
If you measure your KH and GH with a kit that reads one degree of hardness per drop of reagent, the real relationship between 9 dKH and ppm is 180 ppm, or even 200 ppm. When you measure something and read out in one digit, only one digit is useful when you convert that reading to something else. For sure you can't reasonably use 17.848 as the conversion factor.

Hoppy
Hoppy is offline  
 
post #4 of 6 (permalink) Old 02-10-2016, 01:41 AM Thread Starter
Planted Member
 
Iwagumist's Avatar
 
PTrader: (0/0%)
Join Date: Jan 2016
Posts: 184
I just read back over my question and I don't think my question was very clear... What I am TRYING to ask is this: can GH be measured by dKH, or can it only be measured in dGH? Or is there even a difference? The API test uses a one drop to one degree of hardness ratio, but only has dKH marked down on the chart, no section for dGH. So does the one drop to one degree ratio only work for KH or does it work for GH as well? Hope this is making sense... here is a pic of the chart:
Attached Images
 

Last edited by Iwagumist; 02-10-2016 at 02:19 AM. Reason: specify
Iwagumist is offline  
post #5 of 6 (permalink) Old 02-10-2016, 02:10 AM
Planted Tank Enthusiast
 
PTrader: (0/0%)
Join Date: Apr 2015
Location: Queensland
Posts: 525
Quote:
Originally Posted by Hoppy View Post
For sure you can't reasonably use 17.848 as the conversion factor.
For sure you can reasonably use that figure as the conversion factor, because that is what it is. Without doubt. To suggest otherwise is to breed uncertainty.

If the test kit has an accuracy of +/- 10 ppm, that is another issue entirely.

Feel free to edit.
Audionut is offline  
post #6 of 6 (permalink) Old 02-10-2016, 04:55 AM
Planted Tank Guru
 
PTrader: (84/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,015
The circumference of a 1 inch diameter circle is 3.14159265359, not 3.14159265357 Sorry, I'm an engineer.
Audionut and Audionut like this.

Hoppy
Hoppy is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome