Methods of testing

well, i thought i might write a little article about what i have learned about test kits over the years. as a salt water aquariast there is a real need to have accurate results from test kits. i have tried several types and brands of test kits, and researched how they work. so i thought i would share some of what i have learned with you all.

there are 4 types of test kits readily available to aquariasts on the market. i will be over viewing all four types. how they work, how accurate they are, cost, and good brands.

the first and most common type of test kit is the dip strip test. these work by having one or two reagents (chemicals) placed on pads that are glued to a plastic strip. these reagent(s) are activated when placed in contact with the water by causing a chemical reaction based on the waters chemistry. they create a color change by interacting with the reagent(s) this in turn creates a gradient of colors that are then compared to a color comparison chart. these types of test kits are grossly inaccurate, often varying plus or minus 1.0 – 2.0ppm. this is a huge margin of error. that difference can mean life or death for your aquarium inhabitants. i would not recommend these types of test kits for any one who keeps fish, they are quite cheap at under $10 for a all in one test kit. if you insist on using this type of test kit, tetra makes a more ‘accurate’ one. the term accurate is used loosely there.

Methods of testingthe second type of test kit i will go over is the vial color comparison type. this type of test kit uses vials and reagents (chemicals in a dropper bottle). these work by taking a precise volume of water in the test tube. then you place the appropriate amount of drops, often from two or more bottles (some also use a powder reagent). once the reagents have been added and mixed properly a color change will occur, which you then compare to a color chart. typically they use a reaction reagent, and a color indicating reagent. the reaction reagent when added to a sample creates a density difference in the water, when the color indicator reagent is added it reacts by producing an appropriate color for the type of test you are taking. there are a few caveats to these types of test kits. most of these use plastic vials which can over time accumulate trace amounts of reagents which can affect the results if not kept clean. another problem i have encountered with these type of test kits is that when comparing the color to the chart the type of lighting you are reading it in will have an effect on the test results. the best type of lighting to read these in is natural sunlight, as this will give you a more accurate reading. yet another problem with these types of test kits is that you must make sure that the drops them selves are uniform, that the bottom of the parabola (the curvy water line in the vial) is exactly at the ml mark, and that none of the water collects on the cap it self. if these types of test kits are used properly the accuracy can usually be accurate with in 1.0 – 0.5ppm depending on the brand. in my opinion these types of test kits are ok at best, they can give you a base line idea of the waters parameters. i have used several brands of these types of test kits and compared to more accurate ones and out of them all i have found that RedSea’s test kit is the most accurate of this type. the RedSea fresh water master lab will run you about $25 and has all of the necessary tests needed for fw tanks.

the third type of test kit that i will be over viewing here is the titration type of test kit. titration is a laboratory technique by which we can determine the concentration of an unknown reagent using a standard concentration of another reagent that chemically reacts with the unknown. what this means for test kits is that the unknown reagent is the test water sample, and the known reagent are the drops added to achieve a result. these test kits work by taking a precise volume of water in the vial, then adding one drop at a time while counting each drop till a color change occurs. these differ from the color comparison types in that you dont compare a color with titration, instead you are looking for a definite color change from one to another (ex; yellow to blue). the counted number of drops typically is the amount of ppm or meq/l that you are reading. these are the most accurate test kits that use reagents, most are accurate to within 0.05ppm or meq/l. these types of test kits are only slightly more expensive than the color comparison types, but the extra expense is well worth it. a good reputable brand which is the standard in the sw hobby is API. this brand is cost effective, and accurate. API also makes test kits that can be used for both fw and sw applications. a complete fw/sw API lab will cost about $30, and has all the needed tests for fw applications. i would highly recommend titration test kits for any type of aquarium.

the fourth type of test kit is the electronic testers. these work by using a digital read out and a testing probe. you must calibrate the probe with a solution for the type of water you are testing. once calibrated testing is quite simple, you place the probe in the water and the digital readout gives you the reading. they work by creating a slight current in the probe, the probe reacts with the ions in the water either negative or positively charged. these ions create a difference in the amount of current that the probe reads. the digital readout converts this current reading into a value for the type of test you are conducting. these are by far the most accurate of test kits provided on the market. however it is in my belief that the cost and the technology is still in its infancy. there are only a few types of water parameters that these types of test kits read currently. ph, phosphate, nirite, nitrate, orp or redox potential, tds, conductivity, temp, and density. the cost of these types of testers is very high, some can exceed $250 for one tester. it is in my opinion that these testers are not neccicary for the fw enthusiast. they are most commonly used in reef tank applications and are often wired into controller devices. however for their cost they are the most accurate type of tester on the market with 0.01 – 0.05 readings.

Methods of testing now that i have gone over the types of test kits available, i thought it necessary to go over how to properly test water and achieve accurate results. i am only going to cover how to test with test kits that use reagents.

when taking the test sample of water it is important to take the sample from the bottom of the aquarium. as this is where you will get a more accurate base line reading for the overall water chemistry. down at the bottom of the tank or pond, this is where most of the nutrients collect. these nutrients have an effect on the ph and alk (more commonly known as kh, dkh or gh for fw people).

when using vial type test kits it is important that the bottom of the parabola (curvy water line in the vial) is at the ml line marker. if the top of the curve is at the line this is a difference of 0.05ml, this will have a vast effect on the test result. a more accurate way to be certain that there is an exact amount of test water in the vial is to add it drop by drop. there are 20 drops of water to 1 milliliter. if you add the water in this fashion then you are certain to achieve an accurate result. this method removes the user error from the test.

if you are using a color comparison type of test kit, it is important to make sure that you take the readings in natural sunlight, as incandescent and fluorescent lighting have different color temperatures to the light they put out. this difference in color temperature will affect what color the test can appear. another thing to keep in mind when using color comparison types of test kits, is that it is often necessary to do more than one test to make sure your results are accurate.

commonly as venus stated in step 9 of the Goldfish Care 10 STEPS you should be testing for Ph, Dkh, Ammonia (nh3/nh4), nitrite (n02), and nitrate (n03)

however there are a few that i will add to this list. one is phosphate (p04) if you have a HUGE algae problem this could be attributed to having phosphates in the source water. it is rare that tap water has phosphates under 2.0ppm. over time phosphate accumulates in the aquarium water in your tank. this is a contributing factor to what is called “old tank syndrome”. algae loves phosphate! just as much as it loves nitrate, nitrate is another nutrient that will accumulate over time in an aquarium. if you have tested and receive a reading for 8.0ppm of phosphate or higher, a large water change should be carried out of 50%. there are also phosphate scrubbing products out there. however one should avoid products that use aluminum. GFO or granular ferric oxide is a much safer product for your aquarium inhabitants.

also if you are dosing plant supplements it is important to always test for what you add. test before and after. i would not advise adding plant supplements to the tank with out testing before and after. as these supplements are good at certain levels can be quite toxic at higher concentrations. most supplements contain a number of compounds. the ones in trace amounts are near impossible to over dose. however active ingredients are easily overdosed. so please dont dose unless you test for it.

the final test i will add is carbon dioxide(c02). if you have a c02 reactor in your planted aquarium it should be set opposite from the photo period of your tank, and be tested for once weekly. too much c02 in the water will result in extreme ph swings. very low at night and very high during the day.

Methods of testing