test kits and fluorescent room lights

[PDX-PLT]

Hi,

just thought I'd pass along a little tip. I was checking water chemistry last night; since it was after dark I looked at the samples under the light on the kitchen counter. I was surprised that the ammonia was non-zero: and a little concerned, even though it looked pretty low (looked about 0.2 ppm). So I did it again today, with the same result(?) What's going on? An established tank, nitrites zero, nitrates 5 ppm; had just done a 50% WC in a lightly-stocked tank.

Then I realized the kitchen counter lighting was fluorescent. Could it be throwing off the reading? Those lights tend to give a greenish tinge to photographs. Sure enough, when I looked at the sample under a halogen light, the tube was completely yellow (reading of zero). A word to the wise: beware of color shifts that fluorescent lights can cause when looking at test kits!

[Alight]

Not the lights. Does your tap water contain chloramine? If so, the ammonia is probably from treating your tap water with Prime, and is in the form of non-toxic ammonium. If the above is the case, you will always get an ammonia reading right after a water change, but this should to to zero within 24 hours. It's nothing to worry about. The effective ammonia concentration is zero.

[Ed13]

A flourescent tube between 5000k-6500k shows colors more reallisticly than a halogen most likely around 3000k-4100k or lower which tends to shift the spectrum more to the yellow and red part.

[poconogal]

I always view my test results in my kitchen, under the flourescent lights, and if ammonia is 0 (it always is) test result shows as bright yellow. So I don't think its your lights.

[sleonard]

The color spectrum of the lights can and will make a difference to how something appears. You proved the point by looking at the same sample under 2 different kinds of light. The reference standard is sunlight and will be the most accurate. Any kind of man-made light will show some degree of color shift.

Scott

[Ed13]

The reference standard is sunlight and will be the most accurate.
Probably not enough to notice with the naked eye but, depending on location there is a shift of lumens and spectrum received from sunlight!

[PDX-PLT]

The color spectrum of the lights can and will make a difference to how something appears. You proved the point by looking at the same sample under 2 different kinds of light.

Actually, 3 lights. It looks fine under a standard incandescent light as well. Considering fluorescents are notorious for giving photographs a greenish tinge, I'm sticking with the light theory. I have well water so I don't treat it, so it is not chloramines.

Checking under daylight will need to wait until the weekend (checking under actual sunlight will probably need to wait 'til June!).

[Alight]

What does your water, straight out of the tap test with the ammonia test kit?

How about water you know has absolutely no ammonia in it (RO or distilled water).

Always best to have standard with any of the liquid test kits.