KH and GH testing kits

[chatony111]

Hi guys,

I recently acquired some CRS and have noticed on the web that people test for KH and GH in the water for their shrimp tanks. I went to my LFS and bought their Sera API combined kit, however it failed to change colour when i tested it against my tank water. The same thing happened when my LFS tested the same kit on their own water (i got a refund on the kit). 

My question is which kits do you guys use and is the colour change very noticable? Sorry i don't know much about these two WP so if you guys have any tips regarding it i would appreciate it too! Thanks guys

Edited July 13, 2015 by chatony111

[larrymull]

I use API KH&GH, however i'm sure others are more experienced than I am and may offer better solutions for you.

[amkr]

I use the API test kits.

[chatony111]

My bad, i meant to say thats the kit (API) that didn't work well for me

[Grubs]

I use SERA kits.  KH starts yellow in the bottle but goes obvious blue on the first drop, you keep dropping until it goes yellow again.  if it doesn't change colour and stays yellow that means your KH <1.  If you have doubts sprinkle a few grains of bicarb soda into the test vial and it should instantly go blue (bicarb raises KH).  The KH colour shift is easy to see.

GH is muddy green colour in the bottle and 1st drop changes to muddy red, you keep dropping until it goes greenish again.  The colour change from muddy red to muddy green can be quite difficult to see, especially at low GH because only a few drops of colour in the sample vial means the sample is very pale.  At higher GH with more colour in the vial its a lot easier to see.  I normally hold the vial over a piece of white paper and with each drop ask myself does the sample have a red tint or a greeny tint?.  There is an issue that for old (past expiry date) GH kits the red tint becomes a muddy brown - so you're looking for a very subtle shift from muddy brown to muddy green/brown and its very difficult to see...  time to  toss and buy another.    As for KH, if you are uncertain if the kit has changed colour sprinkle some GH booster into the vial and see if the colour changes back to red.

The API kits use the same reagents and have the same colour changes.

 

Edited July 13, 2015 by Grubs

[chatony111]

Thanks for the extensive information Grubs. I shall try again with API then

[jayc]

You can try looking down the test tube, ie. from the top, rather than from the side.

You will be able to perceive slight colour changes better from this view.

 

Alternatively, try Salifert brand for KH tests. You can change to a low range measurement just by reducing the sample water by half and multiplying the results by 2. Detailed instructions in the box, I believe. 

 

Similarly, their Nitrite and Nitrate test kits, can measure high range and low range with the one test.

Look from the top down into the bottle for high range, and look through the side for low range (divide by 10). Shrimples.

 

Unfortunately, I don't think Salifert have a GH test kit.

 

FYI - All of Salifert's test kit instructions in one PDF. http://www.marineaquarium.gr/downloads/SalifertTestKitsinstructions.pdf

 

[cjwuna]

Anyone know how to use api test kits? I've got the drops and vials, just no instructions!!  TiA

[JacksonL]

Anyone know how to use api test kits? I've got the drops and vials, just no instructions!!  TiA

http://www.apifishcare.com/pdf/GH_and_KH_Test_Kit_and_KH_Test_Kit_58-59_Insert.pdf

[cjwuna]

Thanks 

http://www.apifishcare.com/pdf/GH_and_KH_Test_Kit_and_KH_Test_Kit_58-59_Insert.pdf

thanks mate!