MixedFruitBasket
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I know this may be "duh" for a lot of people out there but I wanted to post this because I've been shocked at how many people don't know this (Some of whom have been my friends and even LFS people who should know better). Disclaimer: While there is some cross over for digital test users, for the most part this is aimed at people who use color tests.
API (for example but not excluding other liquid tests) gets a lot of flack about not being accurate (how close the reading is to the true or accept value). I've used API for years and I've tested it against Red Sea and safe alert and had very similar results. Since there is no shared "base line" for any of these tests (except the color chart they give and even that has a margin of error) then the most you can hope for on any test is precision (how close the measurement of the same item are to one another).
Okay here are some of the basic things I have seen when dealing with tests that require reagents of any kind. (Again this will be a "duh" moment for a lot of people but I've had friends who've been surprised they should do this and I'm shocked at how few (almost none that I know of) test kits have instructions regarding this. I've actually called companies and asked at what temp the stuff should be stored. They've said room temp, but also admit sometimes these boxes sit in shipment at unknown temps. I've also had discussions with a chemist friend who has stated the importance of doing these kinds of steps.
1: Temperature. The storage temperature of your test kit can affect its accuracy, precision and longevity. Room temperature seems to be the best storage. Letting it sit in your hot car after purchase (you run into the mall and leave your package in the trunk that sorta thing), shippers letting it sit in a hot truck, store storing it in a non climate controlled storage room, can (I'd almost wager will) affect the contents of the test.
2: Preparation:
A: This is sometimes hard to remember. You are performing a scientific test that needs as few errors as possible. This means prepare your area. Make sure it's clean and free of stuff that might get in your way, get in your test, etc. All tests for each substance are best done if they are done multiple times at the same time. I usually do 2-3 vial tests simultaneously of each test (yes the same brand test and the same substance) but only one chemical test at a time. I.e. don't do phosphate until you've completed the nitrate. This reduces crossover contamination and simple confusion. And one test on my RODI water as a "base line". This way, I can compare results and if you missed something and made a mistake (one too many drops, not all of a drop, etc) that you didn't notice you have a back up. If all your tests come back identical then you've got a pretty good chance you did them right. If they don't then you should retest.
B: Wash your hands. Disposable gloves would be better, but at least wash your hands before and after each test and anytime you are going to come into contact with your tank or a whole new set of chemicals (like you do nitrate then phosphate or whatever).
3: Contaminants:
A: vials should be washed between each use (rinsed is sufficient in my experience) and before each test it should be rinsed again then "rinsed" again in the salt water you plan on testing. This prevents droplets of clean water from affecting your test. Many of these tests are using 2-5 ML of water. A few drops can affect the outcome. When storing vials leave them uncapped and turned over so dust and other particulates don't get on the inside. Vials that have become discolored should be disposed of.
B: DO NOT use your finger as a "lid". I kid you NOT. I have seen LFS employees do this. They cover the end with their finger and "mix" the test tube contents. Your skin is acidic not to mention all the other effects your body oil will have on the chemicals or the chemicals of one test affecting another. On top of that these chemicals are toxic and some (I don't know which) could even be carcinogenic. Your skin absorbs. DON'T DO THIS PLEASE.
C: If you use a syringe (with a plunger), use a new one EVERY SINGLE TIME. Those little rubber plugs on those syringes absorb/collect stuff. Continuous use of the same syringe could contaminate your test. Remember, it only takes a small amount of contaminant to affect the results since you're dealing with such a small amount of fluid. This includes your salt water. Remember you're testing for chemicals, those chemicals could build up in your syringe. Washing it, IMHO isn't good enough. The rubber plunger is the issue. It not only has a seam between it and the plastic, it can form tiny cracks after just a few uses, will have small pores, etc, that can and will collect residue and affect a test. For example, you wash the plunger under your tap water and your tap water contains chlorine. You have a chance for residue to form thus could affect (however slight) your test.
3: Setting up the test:
A: Shake your bottles of liquid reagents no matter the test. I don't mean a ten second wimpy shake, I mean a good minute of vigorous shaking (unless the pamphlet states others wise--and yes read the directions). Many of these vials have fluids that may separate. When they separate guess what, the test comes back incorrect. If you have not been shaking your bottles then you need to throw away the test and get a new one. Remember, separation. Once the fluid separates you can't rely on the test because now there are different amounts of reagent components in the bottle. Bottles with really thick liquid should be shaken even longer. I'm not kidding, this is important. Also shake your bottles in between tests. Like if I do 3 tests on Nitrates, when I go to the 2nd test I re-shake the bottle because I have no idea how long it takes stuff to settle and 30 seconds to a minute might make a difference in accuracy and precision.
B: Pay very close attention to the amount of water in your test tube. Remember, we're using tiny doses. To have the correct amount of water in a test tube (and I have not seen this info in an instruction sheet unless it's been recently added or I missed it) you need to go by the MENISCUS. If you don't know what that is, I'm sure you've noticed how water curves in the test tube? To have the correct amount, you need to have the bottom of that curve at the line. Having just the top of the edges where the water curves or the top of the curve at the line means you have too little. Having the bottom of that curve with a gap between the bottom and the line means too much. If you have to, get *disposable* syringes (these are cheap and can be purchase online from pet/vet supply companies like Vally vet, or A to Z, Lambert, etc) to pull up water and put it in the test tube rather than trying to dip the tube into your tank to collect the water. Disposable pipets are even better. Getting the right amount of water can greatly affect the results of your test results. "Close" isn't good enough. Again, this is a scientific chemical test, you cannot have accuracy or precision on any level if you're sloppy.
C: Pay very, very, VERY close attention to the amount of reagent (chemicals you're putting together) to perform the test. You're dealing with tiny droplets and the droplets themselves already have a margin of error. Losing half a drop on the outside, the edge, having a drop form a bubble before going into the tube, affects your results. If you're not sure, guess what, start over. Again, sloppy doesn't produce precise/ accurate results.
In the case of safe alert some of the tests have powders which say "level spoon" (the spoon included in the test). Again, important to get that right. Personally I scoop up enough to make a mound, pack it down with the edge with a stiff card like a post card (throw away afterwards), then scrape off the excess back into the bottle leaving the edges clean and the powder the exact amount. If a chunk comes out of the middle (and sometimes it does if it's packed as is should be) I re-do. If I put the powder into the vial and part of it sticks to the side, I redo the test. Since the instructions say don't shake, there's no reliable way to get the powder off the side to mix.
D: Order:
Yes, the order in which you put the drops of the chemical in the water matter. If you mess up and put #2 in first, start over. If you mess up and don't shake between applications, start over.
E: Mix the amounts between applications. I noticed recently on the nitrate test (or maybe just finally noticed) API instructions now say to shake the vial for at least ONE MINUTE between the application of each chemical to the vial. I swear it did not say that in my first set of instructions I owned. If it says SWIRL (such as the Safe alert test and a few others) DON'T shake it, but do swirl, slowly and thoroughly for the time suggested, one way then the next (counter clockwise for 30 seconds clockwise for another thirty seconds until you've done the amount of needed time).
F: Between each application, before you pull off that lid, tap the vial with your finger. You know like you see in the old movies where they do that to a syringe. GENTLY so the tube won't break. This is to knock loose any droplets clinging to the lid so that you won't lose it when you open the lid. You will lose some to the edge of the tube (again why getting everything else is important) but this lessens the chance.
4: Time: The time suggested to let the vials sit is important. You're better to let it sit too long then too short but too long can still affect the results (I've learned this the hard way--oh I'll just do this while I'm waiting--thirty minutes later--oh crap). Set a timer, don't trust your "instincts."
Reading the test: This is where your "base line" test comes in handy.
A: Surfaces absorb and reflect light differently. The cards we use are laminated, the color is made from ink, on paper, and the solution you're reading is in glass and made from water. This will affect how light it reflected. The color you see in regards to an object, liquid, etc, is what's being reflected. It's important that you read these tests in a white light. Not your aquarium light, not near your aquarium light, and read all the tests under the same light. Put the tube against the white of the card. Objects around colors will affect how you perceive them. A yellow orange color may look more yellow next to something like red, or pink, where as next to blue or purple, more orange. You may think you're not putting it close to other colors, however the background of your room where you are reading the test matters. Hence, why it's important to make sure the vial is shielded by being placed against the card. Put the edge of the vial against the list of colors. Again, a white streak between them can affect how you perceive the color. Don't overlap or you will change the edge color of your vial. Look at it straight on so the light doesn't refract oddly or reflections of objects around you don't affect the color.
The type of light you read it by will also affect how the color test reads. Warm lights tend to have more yellow and that yellow will affect how your eye perceives the color. Personally I use and LED white light flash light or lamp light and hold the tube against the card under that. It's not perfect, but it's better than the standard room light.
When comparing, compare your baseline test first. If it's off, i.e. lighter or darker, you have an idea that the results stand the likelihood of being off in color, or that your card is discolored. This can be due to a printer running out of ink when they're being printed, faded by sun (protect your cards from sunlight), or even a bad batch of ink when the card was printed. If you have a drastic difference between your baseline color and the card color I'd advise re-doing the baseline test. If it's still off, then call the company and request a new card. DO NOT try and use a card off the internet. Different brand monitors show colors differently, two the dimness setting on your monitor affects the color, also you have no idea what kind of color settings were used when the card was scanned.
When doing the digital tests, believe it or not, you really should be doing it at least three times then take the average between the tests. There is a margin of error with digital tests. Depending on the circumstances sometimes it can be huge. If possible it would be great to compare the results of a test using different readers. Each reader is manufactured, there can be manufacturing differences that could affect your reading. Each of those readers has to be calibrated (not just by you but they have to be done correctly to have that baseline) and this is another place an error can happen.
To see how easy this happens use different thermometers to read the temp of your aquarium. Three different alcohol thermometers can read multiple degrees off. Digital thermometers are only accurate if they are calibrated correctly, but are usually more accurate overall. I've got some digital thermometers that read as much as 5 degrees different from alcohol and the same with alcohol to alcohol.
When this happens, I use an average or I invest in a professional level thermometer for something that requires accuracy like photo developing etc.
The stuff about reagents, temp, etc, all applies to those who use a digital reader. Your reagents that allow that digital reader to work, go bad, can be ruined by temperature, and if they colloids they will separate, therefore need to be mixed every time and if you haven't been mixing (shaking) them you need new reagents. Readers need to be cleaned, application bottles need to be wiped down.
All chemical bottles should be wiped off with a new clean paper towel to prevent build up. All lids should be put back on and tight. If you leave a lid off or fluid leaks out because it's not tight enough, throw it away and get a new one. Evaporation effects the amount of reagent to test water ratio. Spilling means you've potentially disturbed the collide distribution of chemicals in your bottle.
Again, I know this is probably "duh" for some people, but I also know it's not for others.
Edited to add: Be careful of where you buy your tests. Lots of sellers on Ebay and Amazon may be selling "discounted" items or items lost in shipping or recovered from shipping accidents. I know it's often cheaper, the question is is it worth it?
API (for example but not excluding other liquid tests) gets a lot of flack about not being accurate (how close the reading is to the true or accept value). I've used API for years and I've tested it against Red Sea and safe alert and had very similar results. Since there is no shared "base line" for any of these tests (except the color chart they give and even that has a margin of error) then the most you can hope for on any test is precision (how close the measurement of the same item are to one another).
Okay here are some of the basic things I have seen when dealing with tests that require reagents of any kind. (Again this will be a "duh" moment for a lot of people but I've had friends who've been surprised they should do this and I'm shocked at how few (almost none that I know of) test kits have instructions regarding this. I've actually called companies and asked at what temp the stuff should be stored. They've said room temp, but also admit sometimes these boxes sit in shipment at unknown temps. I've also had discussions with a chemist friend who has stated the importance of doing these kinds of steps.
1: Temperature. The storage temperature of your test kit can affect its accuracy, precision and longevity. Room temperature seems to be the best storage. Letting it sit in your hot car after purchase (you run into the mall and leave your package in the trunk that sorta thing), shippers letting it sit in a hot truck, store storing it in a non climate controlled storage room, can (I'd almost wager will) affect the contents of the test.
2: Preparation:
A: This is sometimes hard to remember. You are performing a scientific test that needs as few errors as possible. This means prepare your area. Make sure it's clean and free of stuff that might get in your way, get in your test, etc. All tests for each substance are best done if they are done multiple times at the same time. I usually do 2-3 vial tests simultaneously of each test (yes the same brand test and the same substance) but only one chemical test at a time. I.e. don't do phosphate until you've completed the nitrate. This reduces crossover contamination and simple confusion. And one test on my RODI water as a "base line". This way, I can compare results and if you missed something and made a mistake (one too many drops, not all of a drop, etc) that you didn't notice you have a back up. If all your tests come back identical then you've got a pretty good chance you did them right. If they don't then you should retest.
B: Wash your hands. Disposable gloves would be better, but at least wash your hands before and after each test and anytime you are going to come into contact with your tank or a whole new set of chemicals (like you do nitrate then phosphate or whatever).
3: Contaminants:
A: vials should be washed between each use (rinsed is sufficient in my experience) and before each test it should be rinsed again then "rinsed" again in the salt water you plan on testing. This prevents droplets of clean water from affecting your test. Many of these tests are using 2-5 ML of water. A few drops can affect the outcome. When storing vials leave them uncapped and turned over so dust and other particulates don't get on the inside. Vials that have become discolored should be disposed of.
B: DO NOT use your finger as a "lid". I kid you NOT. I have seen LFS employees do this. They cover the end with their finger and "mix" the test tube contents. Your skin is acidic not to mention all the other effects your body oil will have on the chemicals or the chemicals of one test affecting another. On top of that these chemicals are toxic and some (I don't know which) could even be carcinogenic. Your skin absorbs. DON'T DO THIS PLEASE.
C: If you use a syringe (with a plunger), use a new one EVERY SINGLE TIME. Those little rubber plugs on those syringes absorb/collect stuff. Continuous use of the same syringe could contaminate your test. Remember, it only takes a small amount of contaminant to affect the results since you're dealing with such a small amount of fluid. This includes your salt water. Remember you're testing for chemicals, those chemicals could build up in your syringe. Washing it, IMHO isn't good enough. The rubber plunger is the issue. It not only has a seam between it and the plastic, it can form tiny cracks after just a few uses, will have small pores, etc, that can and will collect residue and affect a test. For example, you wash the plunger under your tap water and your tap water contains chlorine. You have a chance for residue to form thus could affect (however slight) your test.
3: Setting up the test:
A: Shake your bottles of liquid reagents no matter the test. I don't mean a ten second wimpy shake, I mean a good minute of vigorous shaking (unless the pamphlet states others wise--and yes read the directions). Many of these vials have fluids that may separate. When they separate guess what, the test comes back incorrect. If you have not been shaking your bottles then you need to throw away the test and get a new one. Remember, separation. Once the fluid separates you can't rely on the test because now there are different amounts of reagent components in the bottle. Bottles with really thick liquid should be shaken even longer. I'm not kidding, this is important. Also shake your bottles in between tests. Like if I do 3 tests on Nitrates, when I go to the 2nd test I re-shake the bottle because I have no idea how long it takes stuff to settle and 30 seconds to a minute might make a difference in accuracy and precision.
B: Pay very close attention to the amount of water in your test tube. Remember, we're using tiny doses. To have the correct amount of water in a test tube (and I have not seen this info in an instruction sheet unless it's been recently added or I missed it) you need to go by the MENISCUS. If you don't know what that is, I'm sure you've noticed how water curves in the test tube? To have the correct amount, you need to have the bottom of that curve at the line. Having just the top of the edges where the water curves or the top of the curve at the line means you have too little. Having the bottom of that curve with a gap between the bottom and the line means too much. If you have to, get *disposable* syringes (these are cheap and can be purchase online from pet/vet supply companies like Vally vet, or A to Z, Lambert, etc) to pull up water and put it in the test tube rather than trying to dip the tube into your tank to collect the water. Disposable pipets are even better. Getting the right amount of water can greatly affect the results of your test results. "Close" isn't good enough. Again, this is a scientific chemical test, you cannot have accuracy or precision on any level if you're sloppy.
C: Pay very, very, VERY close attention to the amount of reagent (chemicals you're putting together) to perform the test. You're dealing with tiny droplets and the droplets themselves already have a margin of error. Losing half a drop on the outside, the edge, having a drop form a bubble before going into the tube, affects your results. If you're not sure, guess what, start over. Again, sloppy doesn't produce precise/ accurate results.
In the case of safe alert some of the tests have powders which say "level spoon" (the spoon included in the test). Again, important to get that right. Personally I scoop up enough to make a mound, pack it down with the edge with a stiff card like a post card (throw away afterwards), then scrape off the excess back into the bottle leaving the edges clean and the powder the exact amount. If a chunk comes out of the middle (and sometimes it does if it's packed as is should be) I re-do. If I put the powder into the vial and part of it sticks to the side, I redo the test. Since the instructions say don't shake, there's no reliable way to get the powder off the side to mix.
D: Order:
Yes, the order in which you put the drops of the chemical in the water matter. If you mess up and put #2 in first, start over. If you mess up and don't shake between applications, start over.
E: Mix the amounts between applications. I noticed recently on the nitrate test (or maybe just finally noticed) API instructions now say to shake the vial for at least ONE MINUTE between the application of each chemical to the vial. I swear it did not say that in my first set of instructions I owned. If it says SWIRL (such as the Safe alert test and a few others) DON'T shake it, but do swirl, slowly and thoroughly for the time suggested, one way then the next (counter clockwise for 30 seconds clockwise for another thirty seconds until you've done the amount of needed time).
F: Between each application, before you pull off that lid, tap the vial with your finger. You know like you see in the old movies where they do that to a syringe. GENTLY so the tube won't break. This is to knock loose any droplets clinging to the lid so that you won't lose it when you open the lid. You will lose some to the edge of the tube (again why getting everything else is important) but this lessens the chance.
4: Time: The time suggested to let the vials sit is important. You're better to let it sit too long then too short but too long can still affect the results (I've learned this the hard way--oh I'll just do this while I'm waiting--thirty minutes later--oh crap). Set a timer, don't trust your "instincts."
Reading the test: This is where your "base line" test comes in handy.
A: Surfaces absorb and reflect light differently. The cards we use are laminated, the color is made from ink, on paper, and the solution you're reading is in glass and made from water. This will affect how light it reflected. The color you see in regards to an object, liquid, etc, is what's being reflected. It's important that you read these tests in a white light. Not your aquarium light, not near your aquarium light, and read all the tests under the same light. Put the tube against the white of the card. Objects around colors will affect how you perceive them. A yellow orange color may look more yellow next to something like red, or pink, where as next to blue or purple, more orange. You may think you're not putting it close to other colors, however the background of your room where you are reading the test matters. Hence, why it's important to make sure the vial is shielded by being placed against the card. Put the edge of the vial against the list of colors. Again, a white streak between them can affect how you perceive the color. Don't overlap or you will change the edge color of your vial. Look at it straight on so the light doesn't refract oddly or reflections of objects around you don't affect the color.
The type of light you read it by will also affect how the color test reads. Warm lights tend to have more yellow and that yellow will affect how your eye perceives the color. Personally I use and LED white light flash light or lamp light and hold the tube against the card under that. It's not perfect, but it's better than the standard room light.
When comparing, compare your baseline test first. If it's off, i.e. lighter or darker, you have an idea that the results stand the likelihood of being off in color, or that your card is discolored. This can be due to a printer running out of ink when they're being printed, faded by sun (protect your cards from sunlight), or even a bad batch of ink when the card was printed. If you have a drastic difference between your baseline color and the card color I'd advise re-doing the baseline test. If it's still off, then call the company and request a new card. DO NOT try and use a card off the internet. Different brand monitors show colors differently, two the dimness setting on your monitor affects the color, also you have no idea what kind of color settings were used when the card was scanned.
When doing the digital tests, believe it or not, you really should be doing it at least three times then take the average between the tests. There is a margin of error with digital tests. Depending on the circumstances sometimes it can be huge. If possible it would be great to compare the results of a test using different readers. Each reader is manufactured, there can be manufacturing differences that could affect your reading. Each of those readers has to be calibrated (not just by you but they have to be done correctly to have that baseline) and this is another place an error can happen.
To see how easy this happens use different thermometers to read the temp of your aquarium. Three different alcohol thermometers can read multiple degrees off. Digital thermometers are only accurate if they are calibrated correctly, but are usually more accurate overall. I've got some digital thermometers that read as much as 5 degrees different from alcohol and the same with alcohol to alcohol.
When this happens, I use an average or I invest in a professional level thermometer for something that requires accuracy like photo developing etc.
The stuff about reagents, temp, etc, all applies to those who use a digital reader. Your reagents that allow that digital reader to work, go bad, can be ruined by temperature, and if they colloids they will separate, therefore need to be mixed every time and if you haven't been mixing (shaking) them you need new reagents. Readers need to be cleaned, application bottles need to be wiped down.
All chemical bottles should be wiped off with a new clean paper towel to prevent build up. All lids should be put back on and tight. If you leave a lid off or fluid leaks out because it's not tight enough, throw it away and get a new one. Evaporation effects the amount of reagent to test water ratio. Spilling means you've potentially disturbed the collide distribution of chemicals in your bottle.
Again, I know this is probably "duh" for some people, but I also know it's not for others.
Edited to add: Be careful of where you buy your tests. Lots of sellers on Ebay and Amazon may be selling "discounted" items or items lost in shipping or recovered from shipping accidents. I know it's often cheaper, the question is is it worth it?
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