DFWMAS Test day at Frank´s Tanks

On November 11th, 2017, the Dallas/Fort Worth Marine Aquarium Society and Frank’s Tanks conducted a series of tests at Frank’s Tanks. The goal of this event was to

test reliability and accuracy of test equipment by comparing test samples of the same water.
B) to check the yield of various salt mixes. Multiple tests of the same sample were tested using different tests kits that were produced by different manufacturers.

When testing Fritz RPM, the sample tested by the Fritz’s representative (Brandon Hooten) yielded the numbers below. The number to the left is the results the representative recorded using Salifert test kits. The number to the right in parenthesis is what the manufacturer specifications. The salt was hand mixed and was only slightly cloudy at the time the tests were run.
At 1.026 specific gravity (Sg)
Calcium 350 (400-450)
Alkalinity 9.6 dKH (8.0-9.0)
Magnesium 1290 (1350-1450)


My readings for this salt using ELOS test kits were:
At 1.026 specific gravity (Sg)
Calcium 400
Alkalinity 9.5 dKH
Magnesium 1250


A DFWMAS member’s reading of the same salt using Hanna Checkers for Calcium and Alkalinity. An ELOS test kit was used for Magnesium:
At 1.026 specific gravity (Sg)
Calcium 410
Alkalinity 6.8 dKH
Magnesium 850


ATM’s H.O.T. salt was also hand mixed. I believe that everyone on hand was amazed at the higher yield and even more so at how fast the salt cleared up. While ATM explains on their website that the water may show a haze for 5-20 minutes, this water was completely and deceitfully ( I used this term only because you could not tell that it was a bucket of water with nothing in it ) clear within 3 minutes or less! Again, keep in mind that a clear or cloudy salt mixture is neither my deal maker or deal breaker for choosing a synthetic sea salt. They all clear shortly after adding them to your aquarium. Saying this, I am NOT saying anything bad about a salt that clears up rapidly. By the same token, there is nothing bad for me to say about a salt that does not!
The ATM H.O.T. manufacturer specified that the salt be mixed at a ratio of 1 pound to 3.6 gallons of water. After following the instructions, we tested the specific gravity was 1.038. That surprised everyone immediately. ATM attributes this to the power of their anhydrous salt. We added more water and we tested this salt at specific gravities of 1.026 and also 1.021.
A Frank’s Tanks employee tested the water at using ELOS test kits: The number to the right in parenthesis is what the ATM H.O.T. label says the salt should yield:
At 1.026 specific gravity (Sg)
Calcium 400 (430)
Alkalinity 8 dKH (7.8)
Magnesium 1250 (1325)


A DFWMAS member tested the same batch using Hanna Checkers and recorded the following results:
At 1.026 specific gravity (Sg)
Calcium 415
Alkalinity 6.4 dKH
We also tested the ATM H.O.T. salt at a specific gravity of 1.021. The purpose of this was to show the effect that a lower specific gravity has on the test results. Generally, synthetic seal salt manufacturers’ specifications are based on a specific gravity of 1.026. Not mixing the salt to this level is the most common reason you strange or abnormal readings. When was the last time you calibrated your refractometer?


Two DFWMAS members testing the same batch as above using Hanna for Calcium and Alkalinity and ELOS for Magnesium recorded the following results:
Calcium 300 and 350
Alkalinity 6.5 and 7.5
Magnesium 800 and 850


In addition to testing the 2 freshly mixed batches of salt water, we passed around small bottles of saltwater for people to test using their own equipment. The water came from 2 different aquariums at Frank’s Tanks and were labelled A and B. The results were pretty much all over the place. Using sample “A”, a customer used an eXact iDip tester. This testing method did not seem to provide enough information because if the number was too low, it would simply read LO and not provide a value. LO would certainly mean lower than any reasonable or acceptable number. Still, it would seem prudent to know what that number was if you’re going to take action to address the issue.
The results from iDip from sample “A” were:
Calcium LO
Alkalinity 4.26
Magnesium NO READING
Using a Salifert test kits, Brandon Hooten tested Sample “A” and recorded the following results:
Calcium 340
Alkalinity 10.5 dKH
Magnesium 1,500

The 340 reading by Brandon would almost definitely explain the LO reading from the iDip tester. But little else would explain the huge differences in the alkalinity reading unless the 4.26 was not a dKH reading. If it were instead 4.26 meq/L, the actual dKH reading would be 12dkh. That would certainly make more sense if other readings of the dKH were anything near that number. Certainly possibly with Brandon’s reading of 10.6.


The tank that sample “A” was taken from was tested the next morning and it, in fact, had a magnesium level of 1,500 tested with an ELOS kit.
Sample ”B” results were somewhat closer than those of sample “A”. In sample “B”, a DFWMAS member using an ELOS test kit recorded:
Calcium 350
Alkalinity 11 dKH
Magnesium 1,800
Brandon using Salifert test kits on Sample “B” recorded:
Calcium 370
Alkalinity 8.3 dKH
Magnesium >1,500


DFWMAS member using the iDip on sample “B”:
Calcium LO
Alkalinity 3.9 dKH
Phosphate LO
Like the iDip differences noted in sample “A” above, the 3.92 would make sense if this reading were actually 3.92 meq/L. That conversion to dKH would be 11dKH making it at least far closer to the other numbers from this sample.


Finally, we weighed the exact same amount of salt from several brands as we did with the ATM H.O.T. salt to determine the yields.
Red Sea Coral Pro salt yielded (at 1lb of product): 1.024
Fritz RPM salt yielded (at 1lb of product): 1.023
Aqua Vitro Salt yielded (at 1lb of product): 1.024

The numbers in parenthesis are the yield numbers that Aqua Vitro says that you should get with a specific gravity of 1.026. These tests were performed at 1.024 specific gravity using ELOS test kits:
Calcium 350 (400-443)
Alkalinity 11 dKH (9-10.5)
Magnesium 1,100 (1269-1403)



I’ve always believed that the well-being of saltwater fish and corals depended more on consistent parameters versus parameters that are in range and yet change constantly. I believe that a consistent alkalinity of 7 is far better than an alkalinity that moves between a range of 8 to 12. Recently, Frank (of Frank’s Tanks) noticed this in his store.

One of his systems always seemed extremely cold. They never checked the temperature but every time they did a water change, they noticed that the water seemed cold. When they finally checked the temperature last week, it was 72 degrees. All fish and all corals were doing perfectly well.

He then found out that they had turned the heaters off on the Apex months earlier. Everything was fine until he turned them back on. The temperature rose to 77 gradually but obviously fast enough to cause sick fish. Fish that had been in the tank forever got sick and perished. Thankfully, corals are just a bit hardier in most cases. But the consistent 72 was fine. The change was the killer!

This leads us to the main question “why might there be so many discrepancies between manufacturer’s products”? I believe that where liquid reagents are concerned, there are many factors. Most test kits only require 3-5 milliliters of water to test. Some offer syringes to collect this water from it’s source. I believe that from user to user, small and apparently significant differences in how much water we collect can cause some of these differences. What are the chances that everyone who uses a syringe is pulling the exact amount of water? If you don’t think that the smallest difference could matter, you might think about how much greater the challenges are of keeping a small reef versus a large one. How would you measure a drop? Manufacturers ask that you squeeze a drop from a bottle that will ultimately yield a result. But was the second ‘drop’ the same as the first? Was the third ‘drop’ the same as the second? Keep in mind that a single drop in some cases, can materially change a test result. And how about those color charts? You are supposed to be able to determine one shade of blue over another shade of blue that is almost the exact same shade of blue! One person sees one thing and someone else sees something totally different.

Those facts put the Hanna Checker in the conversation because you don’t have to guess a color since it is giving you a digital readout. But how accurate are they? Frank’s observation is that they tend to be about 2ppm off the reading of tests performed with ELOS test kits. ELOS is his brand of choice because he has built his entire business on the test kits and supplements offered by ELOS which he has used for many years. Just take a look at the tanks in his store!
Still, there are many other tests out there that should and allow to get to what is most important, consistency.

And as for the actual analysis of a product, is it necessary for a manufacturer to point out anything other than the fact that their attempt is to always match the previous batch as best they can or exactly if and when possible? Minute differences of any parameter in salt mixes are hardly any more dangerous than minute differences in water temperatures or pH values when performing the proper water change or acclimating a fish from one system to another that has obvious differences. It is exactly why small water changes are usually better for a system than large ones unless there is an emergency that requires a larger change.





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