Can you trust your saltwater test kit OR your testing skills on your reef tank? - BRStv Investigates

A successful reefer is really proficient at maintaining stable aquarium water chemistry because ultimately that stable water is what keeps corals happy and thriving. Getting consistently accurate water test results at home, for a reasonable price, is important to make the necessary adjustments to your water to maintain stable water chemistry.

Aquarium test kits for BRStv Investigates

You need to be able to trust your water test kits in order to achieve success.

To gain that trust, a test kit should be accurate but also consistent. Accurate meaning you can trust the results are within an acceptable range of what a lab grade water test would provide and consistent meaning those results can be achieved each and every time you perform a test.

We pitted our 6 most popular test kits against each other to narrow down the options and help you pick your favorite.

Reefers performing water tests for BRStv Investigates

The experiment

To help clear away some fog around saltwater test kit accuracy and consistency we gave our 6 most popular test kits for calcium, alkalinity and magnesium to 5 reefers with different levels of experience. Each reefer will perform tests for all three of the major reef tank elements using all 6 test kit brands using the same sample of saltwater from our iconic BRS160 aquarium.



We also have a Neptune Systems Trident running on the BRS160 which we include in the data set to see how this innovative automated testing solution stacks up against the competition.

Definition of BRStv Investigates Test Kit Accuracy Graph

In order to determine a baseline for accuracy, we combined all readings from each of the seven testing solutions into an overall average, minus the highest and lowest 10% of readings to remove any extreme outliers. Accuracy was then gauged based on how close our combined results came to hitting that baseline average.

Definition of BRStv Investigates Test Kit Consistancy Graph

For consistency, we simply break down the average of all 5 reefer’s individual results and look at the difference between the highest and lowest results from our testing team of reefers.

Calcium consistancy graph


After combining all of the calcium test results we calculated a baseline average of 512 Parts Per Million (PPM). Aquaforest comes in the closest, within 2 PPM, with an average accuracy of 510 PPM. Next in line for accuracy was Nyos which was followed by the Neptune Systems Trident.

The largest deviation during our calcium tests was the LaMotte with a difference of 45 PPM from our baseline average. This is likely due to the difficulty in reading the color change endpoint where even in the instructions it notes to disregard color change after 5 seconds giving you only a fraction of time to determine the test results.

Red Sea Calcium Test Kit Consitency

Lamotte Calcium Test Kit Consistency

Aquaforest Calcium Test Kit Consistency

Salifert Calcium Test Kit Consistency

Nyos Calcium Test Kit Consistency

Hanna Crystals Alkalinity

For consistency, Red Sea Calcium Test Kit yielded the closest results across the board with only a 10 part per million difference between the highest test of 495 to the lowest at 485 which is absolutely within a reasonable amount of variance.

Hanna showed the biggest variance between the high and low results with a difference of 101 PPM likely due to some difficulty in testing procedures in which we all agreed the dilution step likely led to some inconsistencies.

Alkalinity consistancy graph


With the available alkalinity test kits we had at the time, our baseline was calculated at 7.81 dKH.

Aquaforest takes the cake again for accuracy coming in with only .04 dkH deviation from our baseline followed closely by the Neptune Systems Trident with a variance of only 0.09 dkH. LaMotte showed the largest variance in accuracy at 0.5 dkH.

Hanna Instruments Alkalinity Test Kit Consitency

Red Sea Alkalinity Test Kit Consitency

LaMotte Alkalinity Test Kit Consitency

Salifert Alkalinity Test Kit Consitency

Aquaforest Alkalinity Test Kit Consitency

Looking at consistency for getting accurate alkalinity readings each and every time, the Hanna Alkalinity Checker performed well for all the testers with only 0.3 dKH difference between the lowest and highest test. This goes to show that by eliminating the human eye from having to determine the testing endpoint, the margin for error is significantly reduced.

The least consistent results for alkalinity came from the Aquaforest test kit with 1.85 dkh difference between the lowest and highest test result from our team.

Magnesium consistancy graph


When performing the tests for magnesium you will notice we do not include Hanna or LaMotte in our data set because these companies did not have a saltwater magnesium test kit available at the time of conducting this experiment. With that in mind, our average baseline came to 1389 PPM of magnesium in the BRS160 aquarium.

Aquaforest, again, gave us the most accurate results across the board with an average reading of 1384 PP and Salifert closely trailed with only a 6 PPM deviation from the baseline.

The largest difference in the accuracy category was the Trident at 1308 PPM or 81 PPM difference from the baseline. Being the Trident reading was not an average, we are confident that if we could perform multiple manual tests using the Trident, the average would likely be much closer to the baseline.

Aquaforest Magnesium Test Kit Consitency

Salifert Magnesium Test Kit Consitency

Nyos Magnesium Test Kit Consitency

Red Sea Magnesium Test Kit Consitency

Aquaforest had the tightest group of results and provided the most consistent Magnesium results with a variance of 105 PPM between the highest and lowest result.

Red Sea’s consistency was the farthest apart with a low reading of 1340 and an outlier higher reading at 1600 PPM for a total difference of 260 PPM. We hypothesized this was because of the difference in reading endpoint color changes because when we removed the 1600 PPM outlier result, the variance drops to only 60 PPM from the highest and lowest result. Red Sea’s Magnesium test kit was also the most tedious to perform considering the multiple wait times and mixing requirements.

BRStv question to answer

What is more important, testing for accuracy or consistency?

As with many of the BRStv Investigates looking for the best, there isn’t one right answer to this question.

Advanced reef tank parameters

For the more advanced reefers who keep parameters right on the outer edge of an acceptable range, accuracy would be more important for success. If you start to make adjustments based off even the slightest inaccuracy, the risk for getting into potentially dangerous parameters is increased.

Average reef tank parameters

For the majority, reefers with more common parameters in the middle of the road, testing consistency would be the most valuable. With consistent results, you can make finer, more precise adjustments to tank parameters which ultimately leads to an increased level of overall stability. Meaning that consistency isn’t just how you perform the test each time, but really how each reefer can interpret the end point of the test. The best test kits available will leave little room for error with end results that are very clear and definitive.


The best test kit for you is really is based on which type of parameters you keep; what type of reefer are you? For larger category of reefers who rely on stability to create an awesome looking tank that can withstand the test of time, rely on test kits that provide consistent results test after test. For the average reefer and based on the data from our test that would be the Red Sea Calcium Pro, Hanna Alkalinity Checker and Aquaforest Magnesium Test Kit.

One of the only questions left for finding the best test kits for your tank would be to consider the long term costs and is there a way to get them cheaper? BRStv Investigates has that under wraps with our video that compares the cost per test versus the cost per reagent refill.

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