Nitrate Testing

[russkev]

Hi

Over the last few weeks I've been raising various concerns on this forum around my Nitrate levels. They were being tested and seem to be over 40ppm even after 10% water changes. I was using the Aquarium Pharmaceuticals kit which tested Ammonia, Nitrite, Nitrate and also Ph. Now this weekend I spoke to the guy in my lfs and he suggested that the above kit wasn't accurate and I should use the TetraTest Nitrate tester. I did this yesterday which returned 12.5 mg/l which I'm infomred by the enclosed doc is fine for the tank

The question I have is

1) What is the correlation or conversion between mg/l and ppm ?
2) Which in people's experience is more accurate ?

The question really is which one should I be working with ?

Any comments much appreciated

Kevin

 

[@ombomb]

I think both types of kit are supposed to be very good. Personally I use the API kits and have never doubted them. I assume you have tested the nitrate level of your tap water...

 

[Stickyrabbit]

We always used part per mol (ppm) in Science class. (not that this a reflection on which instrument is best) but I think its relationship at a molecular level to chemical equations might indicate that it would deliver a more specific measurement.
If the test is faulty or the chemicals are stale or corrupted then this might invalidate the test.
The mg/l (milligrams per litre?) is just as good I would think since most fish live within a range. If you are within the paramters indicated then you should be fine.

Are any fish in the tank and if so showing adverse signs?

 

[russkev]

Hi

Thanks for the responses. In the past I've lost a few fish with Columnaris but that was when the tank was still less than 2 months old. It is now over 4 months old and the fish all seem to be fairly happy. I've got 2 Dwarf Gourami and 3 Clown Loach (among others) which I'm told is a good indication of the condition of the water so guess it can't be too far out. However having said all that I bought 2 Zebra Guppies yesterday and placed them in the tank with one dying later yesterday.

The full stock of my Juwel Rio 125 ltr is

2 x Pearl Gourami
2 x Dwarf Gourami
3 x Clown Loach
2 x Red Tailed Guppy
1 x Zebra Guppy
2 x Platy
1 x Albino Pleco

The tests of Ammonia and Nitrite record 0 again with the AP test kit. The tap water was tested again using the old kit and that showed 20ppm so will need to do the same again with the new kit to see.

Cheers

 

[Stickyrabbit]

"The other main way of expressing amounts of a substance is as moles.

A mole (usually abbreviated as mol) is defined as the amount of an element or molecule whose mass expressed in grammes is numerically equal to its atomic or molecular mass. For example, the atomic mass of gold (Au) is 196.97, hence one mole of gold has a mass of 196.97 g. A mole is also defined as the amount of a substance containing 6.02 x 1023 atoms or molecules." (http/www.soes.soton.ac.uk/staff/pmrp/GY102/module4/m4.html)

or

mole [mol]
The mole is the basic unit of substance. It is the amount of substance that contains as many elementary units as there are atoms in 0.012 kg of carbon-12.


So I rate the mg/l are easier to use for ecveryday purposes ? So the accuracy of the test is not determined by the unit of measurement.

Since a mol will vary depending on the substance there is not easy table to use to convert from ppm to mg/l

 

[tttnjfttt]

I have the API test kit, and the card say the reading is in both mg/l and ppm, so i'd assume they are the same. The molecules are really small and have low mass, so i doubt the actual difference would be that much.

 

[russkev]

Maybe my questions are incorrectly written but wondered which test kit people prefer to be most accurate. There is no use by date on either kit so can't rule this out as a possible problem !

The thing that concerns me is that one test kit shows the Nitrate to be over the recommended 40 ppm whilst the new one states that is fine ! Which one do I rely on as being correct ?

 

[bogwood]

I was told that 'mg/l' and 'ppm' are the same... I use Nutrafin test kits and have had no problems/nasty surprise readings...

 

[tttnjfttt]

Last time i used my nitrate API test, i got a false low reading. I repeated the test and made sure to shake the bottles very well before using either, and i got my normal test results.

 

[lizjamie]

1ppm is indeed equivalent to 1mg/litre (for water before you all fail your exams).

I have never used the other kinds but in my 2 week experience I agree that you can get false readings if you dont shake the test tube or tub well after putting the drops from each bottle in.