Bad/Expired API GH/KH liquid test kit? HELP - The Planted Tank Forum
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post #1 of 6 (permalink) Old 03-19-2015, 06:47 AM Thread Starter
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Bad/Expired API GH/KH liquid test kit? HELP


Here I am suffering from severe confusing with no real answer..(well maybe one) BUT I wanted everyone opinion!

I bought an API GH/KH liquid test kit from my LFS. I use RO water in my 8 gallon shrimp tank and wanted to check the GH before re-mineralizing the water.

The instructions for Gh read :

1. Rinse a clean test tube with water to be tested.
2. Fill the test tube with 5 ml of water to be tested.
3. Holding the bottle vertically, add GH Test Solution, one drop at a time. BE SURE TO COUNT THE NUMBER OF DROPS BEING ADDED.
4. Cap the test tube and invert several times after each drop.
5. The test is complete when the water in the test tube, after having been shaken, turns from orange to green. If yo have difficulty discerning the color after the first drop of test solution is added, remove the cap from the test tube and, while holding it over a white background, look down through the tube.
6. The GH value is determined by the number of drops of reagent that must be added to turn the water in the test tube green. (See GH and KH Conversation Chart at end of instruction leaflet) * Refer to pics *

Heres the problem(s) - I never got an orange color using my RO water or my tank's water. I also never got a true "green" color from either water. I obtained a "lemon-lime" (ish) color from 25-30+ drops FOR RO WATER......somethings not right.

I found another forum where people posted their results...

The pics demonstrate; the orange vs. green coloring, my "lemon-lime" color, and someones (1, 10 and 20) drops into their RO water.

Several other people have similar issues online. I also noticed the BOX SHOWS 2007 for the date (though it doesn't list any expiration).


Bump: Per the instructions

# of drops/ dKH/ ppm GH/KH
1 1 17.9
2 2 35.8
3 3 53.7
4 4 71.6
5 5 89.5
6 6 107.4
7 7 125.3
8 8 143.2
9 9 161.1
10 10 179
11 11 196.9
12 12 214.8 (Chart ends)
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post #2 of 6 (permalink) Old 03-19-2015, 09:17 AM
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With RO water, there will be nothing in the water, so the test will be "done" with the first drop, so you won't see one color with 1 drop then another at a later point.

Maybe your GH is actually KH test (blue to yellow)? Try adding some baking soda (or your KH-up), and testing it. For me, the KH is orange in the bottle as well as for the little drops that get left in the cap; the GH is grey/dark-green/brown (camo).
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post #3 of 6 (permalink) Old 03-19-2015, 10:36 AM
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A LFS will try to buy in quantity and as these test kits are not used by many people
they tend to sit there in the store.
I'd get one from an on-line place as their stock seems to rotate better.
But the color(s) in your picture are the only colors I get when I use the kits. Well maybe the nitrate kit is darker.

The shortest distance between any two points is a straight the opposite direction...
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post #4 of 6 (permalink) Old 03-19-2015, 03:02 PM Thread Starter
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Right like you said it should be "done" upon first drop. But never getting a green color worries me. Not about the water but the quality (or lack of) or test kit.

Even the example's "1 drop" equivalent you can tell its green.

I contacted the LFS through their FB page overnight. They aren't open yet so well see what happens. I'm hoping to get refunded or get a new kit from them.. :-/
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post #5 of 6 (permalink) Old 03-19-2015, 04:38 PM
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You really can't test RODI water accurately with aquarium test kits, not even for PH. The best thing to test RODI water, to ensure it is pure, is a handheld TDS meter. If properly calibrated, RODI water should read zero.

If you want to "test" the test kit, mix baking soda (or Seachem Alkaline Buffer). Put 1/4 teaspoon in 5G of water, mix and aerate for a few hours (powerhead in bucket is simplest). Then test with the KH test, should be about 3 drops (in theory it is 2.8, but measurement error, humidity (affects density of the baking soda), and aeration can make a difference. If it's grossly different, the kit is bad. But you should see the normal color change behavior.

If you watch the drops, and how large/small they can be depending on how fast you dispense, different bottles' giving different size drops, you'll realize that this is not a high precision test to begin with.


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post #6 of 6 (permalink) Old 03-19-2015, 04:47 PM Thread Starter
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Makes sense but based on examples it should not be reacting the way it did.
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