API Master Freshwater Test Kit versus API Test Strip Accuracy

[eddie462]

Hi everyone, I have both of the testing products in the title. The liquid test kit reads my two planted tanks at 0 ppm ammonia & nitrite, but 20 ppm nitrate. My API test strips read 0 ppm on all three. I bought JNW brand test strips(I didn't want to order just one thing of Co-op test strips), and they also read 0 ppm for all three nitrogen compounds. What should I believe? My fish don't act ill from nitrate poisoning. These are my tanks by the way. A 75 gallon paludarium with around 30 gallons of water, and a 29 gallon aquarium.

[Guppysnail]

I’ve used so many all reading different I gave up on strips. My api liquid is accurate consistent and reliable.  I have used seachems reactive agent tests as well and they concur with liquid api. (Exception api always shows slight hint green on ammonia due to using prime) my exotics p/aquatics vet uses HACH liquid which is an exact match for api seachem reactive tests. Not that any of that answers your questions but it has been my experience.  

[GameCzar]

20ppm Nitrate shouldn't hurt your fish. 

[Gannon]

I've never found strips to be reliable. Haven't tried the aquarium co-op ones yet though and I hear those are good, but im comfortable with my liquid kit.

[TankofFish]

 liquid test kit is better than any test strip...just my .02

 

[eddie462]

@GameCzar I know it won't kill them, but that's the general rule for most animals to keep the nitrates at or below 20 ppm.

[sudofish]

I wouldn't start worrying until you get above like 40 nitrates. Some are even comfortable with 50. If I had 20 I would think "just right".

[Rory Waliser]

The only test strips I've had good results with are the Tetra brand ones, and even those can be inconsistent. You can have up to 40 ppm nitrates before your fish start to feel it but 20 ppm is good to have for your live plant to pull out of the water column.

[Mmiller2001]

You will need to calibrate your test kits to answer that question. All hobbyist level test kits are inaccurate.

[Scott P.]

I just purchased some API test strips the other day. I already had the API liquid test kit.

I wanted to see just how close they were to each other. Same thing as the OP.

Sort of close but not really. I will stick with the liquid and use it as a baseline.

[BrendaW]

I’m using API test kit and have been seeing what appears to be ammonia reading, no nitrites and some nitrates. The Tetra strip shows no ammonia.  I’ve been dosing with Prime to keep my Betta alive.  Now I read GuppySnail saying there is slight green when using Prime. That may be my problem!  I’ve got a conversation going on this site about cycling my 5g aquarium and someone else said the same about Prime.  

[Guppysnail]

On 7/22/2021 at 10:51 AM, BrendaW said:

I’m using API test kit and have been seeing what appears to be ammonia reading, no nitrites and some nitrates. The Tetra strip shows no ammonia.  I’ve been dosing with Prime to keep my Betta alive.  Now I read GuppySnail saying there is slight green when using Prime. That may be my problem!  I’ve got a conversation going on this site about cycling my 5g aquarium and someone else said the same about Prime.  

Yeah it’s the type of reactive agent used. You can buy others seachems doesn’t show ammonia but I’m so use to an ever so slight green and I’ve had mine up so long and have soooo many plants I’m comfortable with just knowing what my norm is

[BrendaW]

Does your test look like this?

[Guppysnail]

No. It is just enough that it’s not bright yellow but definitely not .25ppm green. 

[Guppysnail]

One indoor sunlight one outdoors

[Guppysnail]

The level of green I see could be camera or my tablet is definitely ammonia not prime 

[Guppysnail]

Putting more thought into this prime is supposed to convert ammonia to ammonium or something like that for 24 hours. If you dose the tank it may not register the ammonia on the strip only the liquid. I’m not a scientist and have no interest in that great debate but it’s just a thought for you. 

[Mmiller2001]

Not my own 

"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".