0 Nitrate?

[Katty]

Lately my planted tank has been showing up with 0 nitrate... I don't know if this is supposed to happen or not.

First off, I had a container of multi-test test strips, one of which is nitrate with turns pink if nitrate shows up. I know everyone's going to want to chime in strips are bad after reading that, but lets ignore that for the moment. I'd used these strips on other tanks before, and they had turned slightly pink, meaning under or around 20 ppm nitrate. Well, last week I randomly decided to test my 20 gallon planted with a strip and the nitrate pad showed up pure white, after waiting 60 seconds per the instructions, meaning 0 nitrate. Huh, strange, but people say strips are unreliable anyways, I thought to myself. I don't remember if this tank ever had a nitrate reading, but it didn't have one now. Yesterday by chance I ended up at the petstore and got a liquid nitrate test (by API) to see what was going on with my plant tank. Got home rather late and tired last night but was excited to try the test, so I did it using the instructions on the back of the card, which showed inverting the test tube at certain times. Huh, it said 0 nitrate for my plant tank. I also tried it on my betta's unplanted tank using the same method I did the first time and got 5ppm nitrate on her tank. Today I was thinking that the instructions on the back were rather ambiguous so I did it again on my plant tank using the word for word instructions in the pamphlet, which involved vigorous shaking at certain points rather than the inverting shown on the card. I thought here the problem would be solved, I must just be doing the test wrong, and I will get some nitrates on this trial. Nope, did it word for word by the instructions and it still showed up as 0 ppm nitrate. I don't think the test is a flunk, because it did give a reading for my bettas tank, although I didn't do the steps right that time. Plus the (purportedly unreliable) test strips showed up 0 as well.

Also, I tested ammonia and nitrIte for the plant tank, and both are 0. Yes, there are fish in the tank I do weekly water changes, more or less 20%.

This is a little baffling to me because my tank is not particularly fast growing or high light or special or anything. It's 20 gallons with two 15 watt bulbs on top, an 8000k and a 5000k bulb. I dose daily with flourish excel, and weekly with some cheap iron plant supplement thing (just trying to use up the bottle).

Heres a bad picture of the tank to get an idea of the growth I have going on. The funny thing with the stripes is a coconut with rubberbands to hold on moss till it sticks btw. Not really anything crazy, and a light staghorn algae problem.

Where has the nitrate gone? I would appreciate any insight any of you can give

 

[aaronnorth]

Its just the innacuracy of test kits - liquid or strips.

There will always be NO3 present, as long as your plants (abd fish) are healthy I wouldn't bother testing

 

[anon02]

Its just the innacuracy of test kits - liquid or strips.

There will always be NO3 present, as long as your plants (abd fish) are healthy I wouldn't bother testing

Yours must be about the 8th opinion that I`ve read about the nitrate tests being inaccurate, is there science behind this ?

 

[ian]

there is... the regent in a NO3 test kit doesn't last long once opened, the regent often isn't 'shook' long enough, and the main reason is that most nitrate test kits actually convert nitrate to nitrite first, then test for the concentration of nitrite. That is, they actually measure the combined concentration of nitrite and nitrate. So in a tank that has no nitrite, you don't get a correct nitrate reading as the reading comes from the nitrite.

 

[anon02]

there is... the regent in a NO3 test kit doesn't last long once opened, the regent often isn't 'shook' long enough, and the main reason is that most nitrate test kits actually convert nitrate to nitrite first, then test for the concentration of nitrite. That is, they actually measure the combined concentration of nitrite and nitrate. So in a tank that has no nitrite, you don't get a correct nitrate reading as the reading comes from the nitrite.

Does this apply to the 4 component Tetra test Ian ?

 

[aaronnorth]

There is no paper on it, but you only have to read the original post to see theirs has just shown 0ppm, and the other hundreds of posts saying the same thing.

That's good enough for me.


You can also test this for yourself by calibrating the kit.

To do this, make up samples of 5,10,20,30ppm (and any others you want) by adding KNO3 to some DI water.
Test your water as you would normally, and add the reagent to the samples too.
You can then compare the colours of the sample and the card so you know which colour relates to which concentration.
Just store the samples for future use (ideally you would make up new samples every time)

This is the only way, unless you want to pay for the lab kits at about £100.

I can give you the formula's if you want to do this.

Thanks, Aaron

 

[ian]

I'm not familier with that one, Anon. But if it's a regent (liquid) test kit i would have thought so. If you're worried i would email Tetra, they are pretty good with thier customer service. I know the API and Salifert test kits work this way.

 

[anon02]

I'm not familier with that one, Anon. But if it's a regent (liquid) test kit i would have thought so. If you're worried i would email Tetra, they are pretty good with thier customer service. I know the API and Salifert test kits work this way.

Cheers Ian, I`m not really worried but it`s interesting to know

 

[Katty]

So basically nitrate tests don't work...

Its a new package and I did the instructions by the book that time. If it's not possible for an average person to get a correct reading with these things, would it be correct generalize that these tests just don't work? I mean, you could calibrate it or do it upside down or when all the planets align during a solar eclipse, but you could also say, yeah, my TV works but you have to point the antenna out the window at a certain time of day but only when it's clear and you can only see the bottom half of the picture and even then it's still fuzzy. But it works!

Not to say I won't try it again to see if I can get a reading off of it. I don't like feeling like I wasted my money xP

 

[Katty]

I tried the test again, did the instructions as they said, word for word, with a timer, and shook the reagent and the vial so much that all the blood went to my hand

 

[SuperColey1]

What fert are you adding? If it has N in it then put a few drops in a test ube with the water and it should show up pretty high!!!

One other reason no-one has stated r.e. the test kits is the user's colour recognition. A liquid or test strip could show the same colour yet you and I may say it is a different reading when comparing it to the dry sample

Also the thread on ammonia details another flaw with hobby kits in that it registers harmless related substances and scares the tank owner into thinking there is a problem.

I don't test and have no idea what any of my parameters are. Even when I didn't do a water change for a year I didn't test. No idea what the KH was at the end of that year. probably zero but no idea. 50% fresh water went straight in at the end of that year and the KH would have risen significantly. Still no idea.

I don't have a problem with people testing however. As long as they take a hobby test kit's readings for the worth they have. A decent attempt at an estimate in most cases.

As Aaron says decent test kits with good accuracy cost lots of £.

AC

 

[Katty]

I use Flourish Excel daily, and then I use some cheap fertilizer with a little potassium sulfate and iron weekly, or fortnightly if I forget.

I don't believe it's a color perception thing in my case. I am not color blind and am pretty good with telling shades apart. The color of the resulting liquid could not possibly get closer to the 0 on the card, no matter the room or the lighting or the angle. The test is definitely coming up with a 0, whether or not there is truly 0 ppm nitrate or not. On the card 0 ppm is a bright lemon yellow, 5 ppm is a school-bus yellow, and 10 ppm is a definite deep orange color.

I don't have any potassium nitrate, but I have miracle grow?? Not that I'd be able to get that to any particular ppm, but I'd be interested to see if it registers the nitrate when it is most definitely there or not.

Also the question of why it registered a 5 ppm on my betta's tank remains. I did not do the procedure right that time, I'd be interested to see if the number changes if I do it correctly, but the procedure is so obnoxious I don't really want to do that again today.

 

[SuperColey1]

Its entirely possible that your nitrate is zero. After all you aren't dosing a source of N so the only N in the tank will be from waste products

On the Miracle grow I doubt it will register. It uses ammonium phosphate and urea as it's N source although I never worked for Scotts.

Most composts and ferts will use urea or ammonium compounds. a tiny few garden liquids will use some KNO3. Quite rare though as KNO3 is a mile more expensive than urea!!!


Easiest way is to check your water report, get their average ppm and then test the tap water. If theirs says 5,10,15,20 whatever then you should get the same colour. At worst you should at least read more than zero. Their readings will of course have been done with expensive testing kits.

For example mine averages 12ppm. however I have no test that I can use to show what I mean as my kits are nearly 4 years old and whilst mostly unused are well past their dates

Plants are growing and fish are breeding so I guess the nitrates are not too low nor too high

AC

 

[Katty]

Just checked our city's 2008 water report, which lists nitrate between 0.2 - 2.1 ppm. I guess I'm just going to have to laugh at this test kit and shove it in the back of my closet

 

[SuperColey1]

That isn't a lot of nitrate and I'm not overly surprised that the test kit doesn't show it up.

I have no idea how heavily planted your tank is so there may or may not be a need to add a source of N and P with the tap levels being so low.

Flourish Excel is a C additive which also helps Iron become available. That speeds up the plants growth. The trace elements are being provided by the other bottle. The gap in the loop is providing the N and P that the plants need. That may well be defficient with you adding the C additive.

However you will know this from seeing algae or defficiencies within the tank. If there are none stop testing and stop worrying as the plants are saying they are happy.

If there are algae/defficiency problems then address the N and P issue first to rule that out then after a couple of weeks if there are till issues then you can move onto seeing what the issue is (if there is one.)

The problem with test kits is that many forget the age old rule which wil apply forever IMO.

IF IT AIN'T BROKE DON'T FIX IT

Therefore many have a lovely tank with no problems. Make the mistake of testing and go Oooh no somethings too low/high. Address something that wasn't a problem and cause a problem by their actions

Therefore if the tank is working, fish and plants are fine etc then plod on with what you have been doing.

If the fish or plants start to show something is wrong that is the time to test (but use the results as an indication rather than a definitive)

AC