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I've become obsessed with nitrates lately, and am trying to monitor them in my tanks. The problem is getting an accurat reading.

I have three brand-new water test kits. Two are the paper-strip style; they're from different manufacturers. The other is a brand-new master kit that uses liquid reagent.

All three give completely different readings.

Paper strip #1 says I have 40 ppm nitrate.

Paper strip # 2 says I have 30 ppm nitrate.

Liquid kit says I have under 10 ppm nitrate. (Yes, I'm positive I did the test right -- I did it twice.)

So?????? I know liquid is supposed to be more accurate, but should the paper strips be that far off the liquid kit and each other?

As I said, they're all new kits.

(To answer the obvious: I'm not a test-kit maniac. I just bought my yearly master kit, but I also keep paper strips on hand for the times I'm in a hurry. I couldn't find the paper brand I like, so I bought another, then found the one I originally was looking for. All of which allows for some very interesting experimentation!)

surprise!!! surprise!!! i cant believe how far those readings are?!? yeah, liquids are suppose to be more accurate than the litmus type tests but when it comes with nitrate liq test...i think its a bit fuzzy... my test demands constant mixing otherwise, it will give unaccurate results... the 2 papers r close but still...the difference is very significant...i frolly, could it be that u didnt mix the bottle one and specially the bottle 2 enuf??? or u didnt mix the final test tube long enuf to give u an accurate result?? other than that, i have no idea how this happened!!!

I had a test kit which used the paper strips. It told me that despite my high pH (it estimated about 8.0), my water was quite soft. That was reeeeeeally odd, so I brought my water into work to test. The pH turned out to be 7.8, but the gH was right up there, too. The strip kit also constantly recorded ammonia readings, even after my tank had been cycled for months. I checked- no ammonia. I certainly will never recommend that anyone use one of these test kits; at least not until some reliable ones come out.

---

And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

Hi,
I'm not surprised to hear about the differences. The test
strips are not accurate and having said that their accuracy
depends on all kinds of variables. Some, of course,
depend upon the manufacturing and packing process. Others
depend upon your treatment of them at home. They must be
in a sealed container, in the dark, and kept cool and
dry.
However, if you keep them in the refrigerator, take
them out, open the container to use one on a hot summer
day,(above say, 80 degrees, with 100% humidity) then
reseal the container and place it back in the
refrigerator, the humidity will condense out and begin
to ruin the strips (must be kept cool and dry,
remember?). You contaminated your own strips.

Liquids are by far the best (between the two) however
liquids demand sunlight and a person able to preceive
subtle changes in coloration. Many discover, when
taking up the aquatic hobby, that they are color blind and
are unable to detect small changes in values. The Aquarium
Pharmacies Nitrate test is one such test. It shifts from
yellow through shades of orange.
With liquids, the ones that function through the "titration
method" are the best. Aquarium Pharmacy Freshwater Master
Kit is one such. In them the first drop changes the entire
sample to one color, and when the exact point is reached,
the entire sample suddenly changes color. Those are the
easiest to read and use. Each drop is so many degrees, and
any conversion to Parts Per Million(ppm) is a simple, basic
math function.

Some of the most expensive test kits have little
"pillows" of powder that you snip open with nail
clippers, and dump into the water sample.
Those are sealed in labratory conditions, and
as long as you get all the powder out of the container and
into the sample the test is accurate... Provided... you
arn't color blind!

Frank


Last edited by FRANK at 01-May-2005 11:29

Last edited by FRANK at 01-May-2005 11:30

-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

I'm not color blind I just can't see shades of red Anything with more red than yellow or blue looks all the same to me. No wonder stuff I called purple others called pink or orange and so on. It all looks the same to me. Aquarium pharm test kits are the best I've used despite the fact their nitrate test showed me I can't see shades of red. The strips have never given me the right ph value and my hardness color is off the test strip or something. It looks darker than the darkest color on there. Also I bought ammonia strips and everything I test with them comes out at 3ppm no matter what I do.

Sham, I don't think you have a problem with shades of red, it's just that the shades of red in the Aquarium Pharmaceuticals test kit are very similar. I consider everything that is darker than their shade of 20ppm as "too much". I would be surprised if there's any human being in this world that can tell the difference between them, especially when you're trying to compare the shades to the result of the test you've just done.

My father is a chemist, and he says even professionals have a problem distinguishing between colors.

It also might explain why I had so much trouble picking paint shades for our walls ...

The only problem I have with the Aquarium Pharmaceuticals tests is the NitrAte tests. It never reads over 10ppm.... even in a tank that hasn't had a water change in a month (I experimented).

Other than that, I'm only color blind to the higher ppms of the NitrIte test. I read it as "if it's not blue, it's bad." I taught my boyfriend that one when the 55g was cycling every time he asked "Is it ready yet??"

Yes, it's the Aquarium Pharmaceuticals nitrate test that's reading really low. Both both strips read much higher. Hmmmm ...

I have been using the aquarium pharaceuticals master test kit since starting the hobby and can tell very well the differences in color and shades. It is a very accurate kit, but care must be taken to follow the instructions carefully. It also helps to test at the same time of day when you do regular tests as parameters may change thruout the day. Another thing is to do the tests IN A VERY WELL LIT AREA. This cannot be stressed enuf. The amount of ambient light may have a very significant impact on your results.
As for the test strips, I have tried a few, can't remember which ones, but When getting them home I did 5 consecutive tests with each one to check accuracy and the values were all off miserably.
spell check

Last edited by divertran at 05-May-2005 12:39