API Test Kit

I've been testing my nitrites every day for a couple weeks and with mine the initial color is bright turquoise and it gets darker depending on the levels. Yours doesn't sound right but I'm not sure what the problem would be.

According to the instruction sheet I am looking at...

Step 4. Wait 5 minutes for the color to develop.
Step 5. Read the test results by matching...... and so on.

Since Step 4 is done before Step 5, uh.......

The instruction does not describe the initial color though. However, the color of the chemical is blue.

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There's a reason for that.... See Step 4.

Until the reagents have had time to react, nothing you see has any meaning whatsoever.

I would say that your light blue color is in fact a "0" reading.

Actually, that means your nitrites are off the charts. For the API nitrite test kits, if the liquid turns purple/red and then goes to light blue, it means it's off the charts.

blue_soda025 said:

Actually, that means your nitrites are off the charts. For the API nitrite test kits, if the liquid turns purple/red and then goes to light blue, it means it's off the charts.

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WTF? I don't mean to sound rude, but where in the world did you come up with that?

Step 4. Wait 5 minutes for the color to develop.
Step 5. Read the test results by matching...... and so on.
Until the reagents have had time to react, nothing you see has any meaning whatsoever.

The only color that means anything is the color after five minutes. Until that point the reagents have not reacted, which is what causes the color we use for measurement.

On the "Fresh and Saltwater Nitrite NO2 Color Card" (API, of course) that I have in my hand, light blue is 0ppm (mg/L).

CaptnDan said:

WTF? I don't mean to sound rude, but where in the world did you come up with that?

Step 4. Wait 5 minutes for the color to develop.
Step 5. Read the test results by matching...... and so on.
Until the reagents have had time to react, nothing you see has any meaning whatsoever.

The only color that means anything is the color after five minutes. Until that point the reagents have not reacted, which is what causes the color we use for measurement.

On the "Fresh and Saltwater Nitrite NO2 Color Card" (API, of course) that I have in my hand, light blue is 0ppm (mg/L).

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That is exactly what API said themselves. I don't know if it was on this forum or not, but a member emailed the company about this (liquid turning red immediately and then light blue) and they said themselves that this means the nitrites are off the charts. I'd like to think they know what they're talking about.
Here is a thread about this issue: http://tropicalfish.site5.com/tfc/showthread.php?t=75084

Please entertain the possibility that you may have read it wrong, or simply remember incorrectly. After all, you don't seem to remember what forum it was even posted on.

I find it odd that this information would be omitted from the instruction manual, which I admit, I only read for the first time tonight.

I never read it before because I never felt the need... I do this kind of thing for a living.

[EDIT] The reference you cited in your edit doesn't support your statement. A member of the board seems to have come to the conclusion that a false reading was being produced. There is no mention of API being involved. They also refer to the "solutions" (plural). There is only one reagent used in Nitrite testing. There are two used in Nitrate testing, but that is simply because in order to test for nitrate, you have to neutralize the nitrite first or you would end up with a reading that was the total of the NO2 and NO3 combined. (This is a gross oversimplification, but I am not up for typing all night and detailing it.)

Hmm, is there something wrong with my test then? I always start out light then get darker

karna68 said:

Hmm, is there something wrong with my test then? I always start out light then get darker

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The instance that Blue_Soda025 was referring to could be due to the fact that the person who had the problem was also dealing with green water, a major algae bloom. We didn't get the full story here.

The nitrite reagent contains hydrochloric acid. It is well within the realm of possibility that when the acid contacted the algae and of course killed it instantly, this caused a color change because the acid was reacting with organic materials.

The normal time to get the nitrites down is like 4-6 weeks. You're at a point where it is entirely possible for you to be seeing Nitrites = 0.

The next thing you should start noticing is a gradual climb in Nitrates, if you haven't seen that already.

I am confident that you are there.....