Advanced Testing and Trace Elements

Starting out in the aquarium hobby, most people simply buy test strips (which I do not recommend
whatsoever) or “master” liquid test kits. While these liquid tritration tests are pretty accurate, it can be
extremely difficult to decipher color charts and differentiate between ever so slightly differing shades of
yellow, green, and red. This leads to frustration and inaccurate test results, and may end up effecting
coral or invertebrate health should a particular element be off. As we get more involved with the hobby,
and want to keep more difficult corals, it may be time to invest into more accurate, easy to understand
test kits, and possibly start testing some trace elements.


These handheld testers are small pod-like devices that you insert a test vial into. Directions are very easy
to follow, as they tell you how much tank water, reagents, etc. to use. Results are displayed on a digital
screen, so no guess work is involved. If used correctly, these tests are extremely accurate and much
easier to use than typical tritations. Hanna Instruments offers a wide range of these handheld devices,
including basics such as calcium, alkalinity, and phosphate, along with trace element tests such as silica,
iron, iodine, nickel, and bromine.

Lab testing

If you don’t want to actually perform easily over a dozen tests yourself, your life just got easier. Some
companies, such as ATI and Triton, have developed tests in their lab that you can send a sample to and
receive your results in under a week. These tests are extremely in-depth, and include all important trace
elements, and even heavy metal contaminant parameters. I highly recommend these tests every year or
so, more often if you are experiencing problems such as coral bleaching or algae blooms that seem to
have no real cause. It could reveal that an often overlooked element is off in your tank. If you are
keeping corals such as Acropora, Montipora, or Chalices that often lose color in many tanks, these tests
are a good idea as little-known traces such as iodine and potassium play a large role in coral color,
growth, and overall health.


Some tests are simply a device or probe that is dipped into the aquarium to receive a reading. Most
commonly, this is a pH or temperature probe that immediately gives you a digital reading. Some
companies like Ice Cap have also produced instant salinity readers that are even easier to use than
refractometers as they are simply held in the water for a few seconds. Calcium, ORP, and alkalinity
probes are also being made by companies such as Pinpoint and Seneye. These are usually the most
expensive option, but are the most reliable way to always know your parameters and if anything needs
to be corrected. If you are able to save up some money and want to be able to automate your tank for
the most stable environment possible, I highly recommend these monitoring units.

Important trace elements to test for

Here is a list of important parameters to test for if you are keeping more advanced corals, or just want
better color and growth rates.

  • Strontium- This is a major ingredient in aragonite. Aragonite is a mineral excreted by corals, worms, and
    bivalves. This fact, coupled with much faster growth rate in test aquariums dosed with strontium shows
    the importance of strontium in healthy coral and invert growth.
  • Boron- Helps maintain pH and has been shown to increase growth of coralline algae and excretion of
    aragonite by corals and inverts. Also enhances red, yellow, and orange colors within corals.

Advanced Testing and Trace Elements

  • Potassium- Tests show that tanks with potassium dosing see enhanced growth rates and better blue and
    purple coloration in clams and corals (especially Montipora and Acropora).
  • Iron- In tanks without iron, corals appear pale. Green, red, and most other colors are all intensely
    enhanced when iron dosing is used. It also helps oxygen transport in the respiratory system of fish.
  • Iodine- Shown to help macro algae and sponge growth. It may also be an antiseptic for coral and help
    them fight off diseases like tissue necrosis.

A quick note about calcium, alkalinity, and magnesium

While beginner articles review the proper levels and some basic tests hobbyists use to measure these
variables, it is important for us to understand how the three interact with each other. This further
knowledge helps us understand why our parameters need to be kept constant and at the correct levels
instead of simply doing it because we are told to.

Firstly, understand that alkalinity is a measurement of the total amount of carbonate, bicarbonate, and a
few other ions. Coral utilizes bicarbonate. Calcium and bicarbonate are used by corals to produce
calcium carbonate. Naturally, calcium and carbonate combine into insoluble calcium carbonate as these
to molecules are naturally attracted to one another, This causes it to precipitate out of the water.

Calcium is naturally much more abundant than carbonate and bicarbonate (alkalinity), so it does not
deplete as quickly. If you have excess of either alkalinity or calcium, more precipitation will occur,
therefore reducing the level of it and the other element. If you have a shortage of one element, corals
cannot use the other and will not be able to build skeleton.

Now, remember how calcium and carbonate can precipitate out as insoluble calcium carbonate? Here is
where magnesium comes into play. Just as calcium and carbonate are attracted to each other, they are
also highly attracted to precipitated calcium carbonate. So, precipitation will naturally pull more and
more calcium and alkalinity from the water and leave it unusable to corals. Magnesium actually binds to
the surface of the calcium carbonate crystal. In doing so, the magnesium ion has made the calcium
carbonate precipitation less attracted to calcium and carbonate, leaving them free in the water column
for coral to use. This is why tanks with low magnesium levels often don’t have much coral growth and
have so much white precipitation around pumps and heaters. These three elements must all be kept
within healthy levels for coral to be able to use any of them.

Final words

While everyone in the aquarium hobby has their favorite brand of test kit or probe, their function is
universal. While the above tests are typically more accurate than tritration tests, they are not always
required to have a healthy tank but rather aim to simplify testing for the user. Most people overlook
testing altogether and in turn can run into major problems with their tank, especially reefs. Even if you
have been in the hobby for decades and haven’t felt the need to test your parameters, it’s a good idea
to do so to ensure you are providing the best environment as possible. If all of your basic tests come
back with good results and you still aren’t seeing the growth or color of your corals that you want, it
may be time to test for the above trace elements or others that I have left off of this list. Either way,
performing regular water parameter testing is a good habit that I believe every single hobbyist could
benefit from.

36 thoughts on “Advanced Testing and Trace Elements”

  1. conner stumpf

    Great read on some of the elements. With our ability now to supplement pretty much anything, it’s good to refresh on what the purpose of each is

  2. Victoria Brewer

    The 3 Major elements are so essential to reefing and are fairly easy to test for everyone should test for them

  3. silvercityreefer

    I find the titration test kits to be the fastest and easiest way to text my parameters. However, I do have a Hanna Checker for Calcium and it’s much nicer to have an accurate result every time. I plan on purchasing addition checkers for Alkalinity & Phosphate as it’s important that these test results are as accurate as possible.

  4. So many books and articles say that you don’t need to do this in a nano tank. It’s confusing to try to figure out. I keep considering testing with Triton Labs to at least get a baseline.

  5. The amount of knowledge is mind boggling! I’m fairly new to reefing, only a couple years under my belt. I have yet to get to the stage where Its necessary to do the over the top testing…but I look forward to the science of it all

  6. Diana Aliprandi

    Are use Hannah and Red Sea test kits about 2 to 3 times per week to check my water. I do need to send my order out to be fully tested. Thanks for the article

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