Reliability of old API test kits - The Planted Tank Forum
 
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post #1 of 6 (permalink) Old 12-25-2015, 09:47 PM Thread Starter
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Reliability of old API test kits

I just got a new API test kit for xmas, replacing a very old one I have. I believe the old one is 7 years old, although the ammonia test kit is somewhat newer, but still probably 5 years old (I did a lot of ammonia testing the first couple of years).

One difference with the new kit is all the bottles are stamped with an expiration date about 5 years from now. None of the bottles in the old kit have expiration dates.

Here are the results:

  • ph Low 6.4: Both kits tested the same
  • ph High 8.2: Both kits tested the same
  • Ammonia 0.0: Both kits tested the same
  • Ammonia 2.0: Both kits tested the same
  • Ammonia 4.0: Both kits tested the same
  • Nitrate 0: Both kits tested the same
  • Nitrate ~20ppm: The older kit was a noticeable shade lower, maybe making it low by about 5-10ppm.
  • Nitrate 45ppm: Both kits tested the same, but it's very hard to tell the difference of even 20ppm at this level.
  • Nitrite 0: Both kits tested the same
  • Nitrite .50: Old kit .25, new kit .50.
  • Nitrite (very very high): Old kit .50. New kit through the roof.

For the Nitrite measurement, Iím used water from a tank that Iím currently cycling. The old test kit has been consistently measuring .5ppm the past week (which seems too low and too consistent). The new kit shows it through the roof, which seems right. Also, the old kit changed colors right away, and has a ďdirtyĒ look to it.

For the .25 Nitrite measurement, I used RO water with 1 drop of the water from the cycling aquarium, which is about 1% of the water measured. So that probably means the tank is at 25ppm, which is believable considering it was done with ammonia cycling a week ago, and I havenít done a water change yet.

My conclusion: don't throw out your old test kits, but don't count on the nitrite kit being accurate, especially for high nitrite values.
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post #2 of 6 (permalink) Old 12-26-2015, 05:45 PM
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The API GH test kit is one that doesn't age well at all. If it is over a year old you will probably find it no longer works. I have even had a brand new, off the LFS shelf, GH kit not work at all. (When it doesn't work, one drop gives you a faint final color, but no number of drops will give you a color change.) Tetra GH test kits seem more durable and easier to read.

Hoppy
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post #3 of 6 (permalink) Old 12-26-2015, 05:52 PM
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I had the same experience with GH kits that Hoppy described.

Also, while they don't have expiration dates, bottles should have the month and year of bottling stamped on them. Haven't checked new bottles for it.
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post #4 of 6 (permalink) Old 12-26-2015, 06:44 PM Thread Starter
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Quote:
Originally Posted by kevmo911 View Post
Also, while they don't have expiration dates, bottles should have the month and year of bottling stamped on them. Haven't checked new bottles for it.
The old bottles I have just have the lot # printed on the label, and a single digit number on the bottom of the bottle (mine have 2, 3, or 8).

The new bottles have the lot # and expiration date printed on the bottle just above the label, and also have a one or two digit number on the bottom of the bottle (mine have 1, 2, 7, 9, or 10).
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post #5 of 6 (permalink) Old 12-28-2015, 06:09 PM
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Quote:
Originally Posted by cjp999 View Post
The old bottles I have just have the lot # printed on the label, and a single digit number on the bottom of the bottle (mine have 2, 3, or 8).

The new bottles have the lot # and expiration date printed on the bottle just above the label, and also have a one or two digit number on the bottom of the bottle (mine have 1, 2, 7, 9, or 10).
For the old bottles, the last for digits of the lot number should be the month and year of manufacture.
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post #6 of 6 (permalink) Old 12-29-2015, 06:56 AM Thread Starter
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Quote:
Originally Posted by kevmo911 View Post
For the old bottles, the last for digits of the lot number should be the month and year of manufacture.
In that case, most are 5 years old, except for the ammonia tests. The ammonia #1 bottle has 0807 as the last four digits. It's possible it's that old. I replaced the ammonia bottles (I think from ebay), so maybe I got something that had been on the shelf a long time. The ammonia #2 bottle has no lot # on it.
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