Tropical Fish Forums

[Subligaria]

Hi,

Am I the only one who's experienced differing test results from differing test kits?

When I used my Tropic Marin saltwater kit, I got Nitrite between 0.05 to 0.1, ppm and Ammonium around 1 ppm.

This struck me as unlikely, since my 48L tank has a protein skimmer and Polyfilter sponge (which I'm sure is removing excess Nitrite and Ammonium) in the filter. So I re-tested for Nitrite and Ammonium via two standalone Aquarium Pharmaceuticals tests. The resuts were 0 for both.

What gives? Is the first kit unreliable?

Any explanations welcomed.

[Darkblade48]

It's difficult to say whether a test kit is reliable/accurate or not, without first testing it on a reference solution.

The best way to check whether your test kits are working properly are not is to mix up a reference solution (I.e. with known nitrate concentration) and then testing it against the test kit.

I think Tom Barr's website has some good references regarding how to make a reference solution with a known nitrate concentration.

[Subligaria]

Hi,

It's Nitrite that's in dispute. I don't have a standalone test kit for nitrate.

Do you have an URL for Tom Barr's website?

[Luna]

You can do a reference solution for ammonia fairly easily. (And you don't need pure ammonia to do it.) I'd have to think...

Here's the link for Tom Barr's reference.

http://www.barrreport.com/estimative-index/3263-how-make-no3-po4-reference-solutions-repost-left-c.html
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--Kathy--

[Subligaria]

Thanks for the URL.

Making the reference solution is too technical for me.

I was just wondering whether other aquarists have also had reason to doubt test results. I take it you have?

[Luna]

No, but I have a biology degree so had to know how to make reference solutions for lots of experiments in college.

It's actually pretty easy. I can't do the math on a Saturday, but maybe I'll have it worked out tomorrow.
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--Kathy--

[FloridaBoy]

Subligaria, in my experience, MOST test kits are indeed unreliable, simply because their reagents are too old. Two brands of kits can give completely different results, in fact, it is not unheard of that two of the SAME BRAND kits can give completely different results. Aquarists have complained about this for years, and as a hobbyist I eventually stopped buying test kits altogether. Having worked in the retail side for several years, I can tell you those boxed test kits can sit on the shelf for a long, long time before they are ever purchased.

Have your water tested at a good local marine shop to be sure of your situation, and make sure they are using fresh reagents! Here are more thoughts on the subject:
http://www.wetwebmedia.com/mtestbrands.htm
http://www.wetwebmedia.com/martstkitfaq2.htm
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Keepin' marines happy for 25 years

[Subligaria]

Thanks for that.

Seems like marine enthusiasts get ripped off by the Trade in so many ways.

Think I'll just assume the Polyfilter is keeping everything OK . . .

[FloridaBoy]

Hmmm, well with regard to ammonia and nitrite, that could be dangerous...
My advice: have your water tested at a good local marine shop.
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Keepin' marines happy for 25 years