# Nitrate and Phosphate test solutions



## JET (Dec 20, 2008)

Could someone please tell me how to make test solutions for nitrate and phosphate to calibrate the test kits with?


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## Diana K (Dec 20, 2007)

Go to the fertilator program linked at the top of this page. This will show you how much of certain chemicals, added to a certain volume of water will result in how much of a change in each of the macros and some micro nutrients. 
Might take a little math on your part, but should be easy to figure out. 
Most of the chemicals listed are available from 
www.aquariumfertilizer.com

Much more accurate if you can weigh the chemicals, not measure with a teaspoon. For this you will need a scale that measures perhaps up to a few grams and down to fractions of grams.


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## William Beebe (Jan 7, 2008)

Nitrate and Phosphate test solutions as per my calculations are the following. If anyone comes up with a different calculation, please advise. I don't claim to be a chemist.

Nitrate. For a 12 ppm solution, add 0.067 grams of KNO3, Potassium Nitrate to one liter of water.

Phosphate. For a 1.0 ppm solution, add 0.0754 grams of KH2PO4, Mono Potassium Phosphate to ten liters of water Obviously you'll want to discard 9 liters, but making a larger batch provides greater accuracy.

When comparing my Phosphate kit, with the above test solution the kit proved to be fairly accurate. 

When checking my Nitrate kit, with the Nitrate test solution, the kit was way off. I called the manufacturer. He advised me that the kit was probably out of date and suggested that I shake it vigorously for several minutes. This made a dramatic improvement, but I trashed the kit anyway. I got a new Nitrate kit of a different brand. The new kit showed my Nitrate 12 ppm test solution to be 80ppm! I am contacting the manufacturer to ask what he suggests, and will report his response.

IRON I had problems with my iron kit as well. It came with a test solution which is a super idea! As per the manufacturer's own test solution is was way off, but the manufacturer was pleased to send me a new kit which works well. Can we mention brand names on this site??? It was SeaChem. 

Anyway, I suspect the plant and algae problems which I have had for the past two years are possibly due to bad readings from test kits.


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## Aquaticz (May 22, 2009)

Look for that myself this AM
Hoppy wrote this (of course) 


Calibrating Test Kits - for non-Chemists


I received a request to write something like this, so: (I hope someone will check this for accuracy.)

Calibrating Test Kits

Calibrating a test kit means using that kit to measure some water samples with known concentrations of the substance being tested for, and using those test results to verify that the test kit is accurate, or to train yourself to recognize the colors that correspond to the concentrations you want to test for. Hobby test kits are not laboratory quality tests. That means we don’t need extreme accuracy in the standard test solutions we use for calibration. If we have a good quality gram scale, with +/-.01 gram accuracy, and good laboratory glass graduated cylinders to measure water volume, there are other articles that tell how to make very accurate standard solutions. The methods described here are for use with ordinary kitchen measuring equipment, measuring spoons and cups. And, the Fertilator calculator on APC was used to easily calculate how to mix these.

Nitrate Test Kits

First, buy a gallon of distilled water from your local grocery store. Use that to make the test standard solutions.

1. Add 1/4 teaspoon - a level measure, not a heaping measure - of KNO3 to 4 cups of distilled water (one quart). This gives you 4 cups of 800 ppm nitrate water.
2. Mix 1/4 cup of that 800 ppm water with 1 3/4 cups of distilled water. This gives you 2 cups of 100 ppm nitrate standard water.
3. Mix one cup of that 100 ppm water with one cup of distilled water. This gives you 2 cups of 50 ppm nitrate standard water.
4. Mix one cup of that 50 ppm water with one cup of distilled water. This gives you 2 cups of 25 ppm nitrate standard water.
5. Mix 1/2 cup of that 25 ppm water with 3/4 cup of distilled water. This gives you 1 1/4 cups of 10 ppm nitrate standard water.
6. Mix 1/4 cup of 25 ppm water with 1 cup of distilled water. This gives you 1 1/4 cups of 5 ppm nitrate standard water.
7. Use your test kit to measure the nitrate concentration in each of the 5,10,25, and 50 ppm nitrate standards. If you wish, add the 100 ppm standard to that set.
8. Compare the colors of those to the color card for your kit, and either verify the accuracy of the kit, or use those colors to train yourself to recognize the colors.

Your nitrate test kit is now calibrated. You can store the standard solutions in tightly sealed bottles for an indefinite period of time for future calibrations. Ideally, you calibrate the kit each time you use it.

Phosphate Test Kits

First, buy a gallon of distilled water from your local grocery store. Use that to make the test standard solutions.

1. Add 1/4 teaspoon - a level measure, not a heaping measure - of KH2PO4 to 4 cups of distilled water (one quart). This gives you 4 cups of 1000 ppm phosphate water.
2. Mix 1/4 cup of that 1000 ppm water with 2 1/4 cups of distilled water. This gives you 2 1/2 cups of 100 ppm phosphate standard water.
3. Mix one cup of that 100 ppm water with one cup of distilled water. This gives you 2 cups of 50 ppm phosphate standard water.
4. Mix one cup of that 50 ppm water with one cup of distilled water. This gives you 2 cups of 25 ppm phosphate standard water.
5. Mix 1/2 cup of that 25 ppm water with 3/4 cup of distilled water. This gives you 1 1/4 cups of 10 ppm phosphate standard water.
6. Mix 1/4 cup of 25 ppm water with 1 cup of distilled water. This gives you 1 1/4 cups of 5 ppm phosphate standard water.
7. Mix 1/4 cup of 5 ppm water with 1 cup of distilled water. This gives you 1 1/4 cups of 1 ppm phosphate standard water.
8. Use your test kit to measure the phosphate concentration in each of the 1,5,10, and 25 ppm phosphate standards. If you wish, add the 50 ppm standard to that set.
9. Compare the colors of those to the color card for your kit, and either verify the accuracy of the kit, or use those colors to train yourself to recognize the colors.

Your phosphate test kit is now calibrated. You can store the standard solutions in tightly sealed bottles for an indefinite period of time for future calibrations. Ideally, you calibrate the kit each time you use it.

Other Test Kits

To follow, maybe


Calibrating KH test kit


KH Test Kit

First, buy one gallon of distilled water from your local grocery store. Set a reasonably accurate thermometer on the kitchen counter near where you will be working. Get an empty plastic bottle that contained bottled non-carbonated drinking water. Wash the bottle with plain tap water a few times, then rinse a couple of times with distilled water.

1. Add enough distilled water at near room temperature, or slightly above, to the bottle, to get it about 2/3 full, or at least 1 cup of water.
2. Add about 5 teaspoons or more of bicarbonate of soda, sodium bicarbonate, baking soda to the water and gently swirl it around a few seconds.
3. Make sure there is still some undissolved baking soda at the bottom of the bottle.
4. Squeeze the bottle slightly to expel some of the air, and cap it to seal the bottle.
5. Leave it beside the thermometer for a few hours, gently swirling it a few times during that time. Make sure there is always some undissolved baking soda left at the bottom of the bottle. (Vigorous shaking of the bottle will cause some of the carbonates to break down, leaving CO2.)
6. Record the thermometer reading in degrees Celsius.
7 If the temperature is 18 degrees, you will need 1.5 ml of that water, at 19-20 degrees you will need 1.4 ml, and at 21 degrees you will need 1.3 ml.
8. Measure 2 cups of distilled water into a very clean bottle that can be capped.
9. Use a cleaned syringe, that has been rinsed with distilled water, to suck up from well under the water surface of the baking soda saturated water more than 2 ml of water. (Make sure you don’t suck up any of the undissolved baking soda from the bottom of the bottle.)
10. With the syringe “needle” under the surface of the distilled water, add the amount per step 7 of saturated solution to the distilled water, and cap the bottle. Gently swirl it to mix. You now have a bottle of 10 dKH water.
11. Add 1/2 cup of the 10 dKH water to 1/2 cup of distilled water to get one cup of 5 dKH water.
12. Add 1 cup of the 10 dKH water to 1 1/2 cups of distilled water to get 2 1/2 cups of 4 dKH water.
13. Add 1/4 cup of the 10 dKH water to 1 cup of distilled water to get 1 1/4 cups of 2 dKH water.
14. Use your KH test kit to test the KH of the 2, 4, 5, and 10 dKH samples. Record the results.
15. If the results agree with the known KH of each sample, your kit is calibrated. If not, you can make a graph of the kit readings on the “X” axis versus the known values on the “Y” axis, and use that to convert the kit readings to correct readings. Your kit will then be calibrated.
16. For future calibrations, store these standard solutions in tightly sealed bottles, labeled with their KH values.
17. For best accuracy, calibrate the KH test kit every time you use it.

This procedure will be accurate to about +/-10-20%, depending on how carefully you do the measuring.

__________________

Hoppy


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## Elohim_Meth (Nov 4, 2007)

William Beebe said:


> Nitrate. For a 12 ppm solution, add 0.067 grams of KNO3, Potassium Nitrate to one liter of water.


You have mistaken probably. 12 ppm NO3 is given by 0.01957 g/L KNO3. 
KNO3 contains 61.33% of NO3. 


William Beebe said:


> Phosphate. For a 1.0 ppm solution, add 0.0754 grams of KH2PO4, Mono Potassium Phosphate to ten liters of water


Wrong again. KH2PO4 contains 69.79% PO4, so 1 ppm PO4 is 1.43 mg KH2PO4 per liter or 0.0143 g per 10L.


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