Reef Aquarium Chemistry Maintenance

 

By Carl Strohmeyer-PAMR 35+ years experience

CALCIUM

Calcium is an essential element required by our reef aquarium. It is the building block for many hard corals, but is still required by all reef inhabitants, even fish! Your reef aquarium calcium level should be 400-450 ppm.
Since fish in marine environments constantly drink the water around them, they have a chemistry that is in sync with their environment.
A regular dosing/supply of calcium also supplies essential mineral Cations that again all reef inhabitants require.

Further Reading:
*Do Fish Drink? Osmoregulation in Fish
*Aquarium Redox, Including Cation replacement

Use of popular Calcium Chloride Dehydrate products only or along with economy Soda Ash Sodium Carbonate products sold by discount bulk suppliers can result in a slow build up of sodium chloride even with a stable specific gravity or salinity, resulting in less than optimal ionic balance for your reef aquarium.

This is where the 3 step Balling Method is superior as no additional Sodium Chloride is added nor is it concentrated.


Recommended Product Resources (sponsors this hobby with websites such as this):
*AAP Bio-Calcium Original Balling Set; Parts A/B/C.
*SeaChem/AAP Reef Advantage Calcium

Other methods of calcium maintenance include Kalkwasser, Calcium reactors, and products such as "Reef Calcium; polygluconate".

While Kalkwasser is popular among many advanced marine aquarists, caution should be used with this method of adding calcium to your marine aquarium. This is not to say Kalkwasser does not work, in fact introduced properly it is an excellent way to regulate calcium and alkalinity in saltwater aquariums. Here is how Kalkwasser works:
Used properly Kalkwasser (Calcium Hydroxide) is slowly dripped into your aquarium, it captures free Carbon Dioxide present in the tank water and converts it to Bicarbonate ions.
However if you drip too fast or if there is not enough Carbon Dioxide available in the water, Carbonate ions will be formed which will make the Ca++ you are trying to add to your tank get wasted by the useless precipitation of Calcium Carbonate (often forming a white residue that precipitates out of your aquarium).
This too rapid addition of Kalkwasser may actually cause the Calcium and Alkalinity in your tank to go down instead of up.
See the equation below:
Ca++ + 2(HCO3-) + Ca++ + 2(OH-) <==> 2 CaCO3 + 2 H2O

Often even a slow drip of Kalkwasser (Calcium Hydroxide) can cause the above reaction if there is not enough CO2 present in your marine aquarium.
One method to avoid this is to add 15ml of 5% Distilled White Vinegar (Acetic Acid) into a 1 liter or 1 quart container.
Dissolve 1/2 teaspoon of Kalkwasser into the Acetic Acid, and then dilute to 1 liter (1 quart) volume with either RO/DI water (tank water can be used in a pinch).



A Calcium Generator/Reactor is another popular method for maintenance of calcium and alkalinity as well as KH/pH regulation, especially in marine/reef tanks heavily stocked with stony corals.
A calcium Reactor works by providing a steady stream of calcium (and some Strontium too) by using CO2 in the reactor. The CO2 then "reacts" with the Calcium Carbonate producing calcium ions and carbonate ions (the carbonate ions increase alkalinity).
Although I have NOT had an instance where this was an "essential" device for my reef tanks, it can be very useful for previously noted reasons.
I have also had issues of too much CO2 getting into the marine/reef aquarium resulting in drops in pH and Alkalinity. This is not to say CO2 is "bad" for a marine/reef aquarium as it is needed for photosynthesis in the same way it is needed in a freshwater planted aquarium, however a CO2 level that constantly crashes your pH/Alkalinity is simply too much CO2!

Under normal circumstances/conditions a Fluidized Filter utilizing Oolitic sand media can accomplish similar results, however for high bio load reef tanks with large amounts of stony corals, a Calcium Reactor will produce more calcium.


Kalkwasser and Calcium Reactor Information Referenced from:
*Aquarium Chemistry; Use Of Kalkwasser, Calcium Reactors

Resource for basic but accurate Calcium Test Kit:
API/AAP Calcium Test Kit

Resource high performance Fluidized Sand Bed Filters:
Fluidized Sand Bed Filters from AAP

ALKALINITY

Which is better Sodium Carbonate vs Bicarbonate?

First what is the chemical difference:
Sodium Carbonate = CO3--
Sodium Bicarbonate = HCO3- (the "Bi" means two, as in H + CO3)

Next, a little about pH since alkalinity is what generally stabilizes pH in our aquariums. pH = a measurement of H+ and the more H+ the lower the pH and less Alkalinity in short. Molar value wise, it takes twice as much as Bicarbonate as Carbonate to raise the Alkalinity up 1 Equilibrium unit. Volume wise it is 0.6 tsp of Bicarbonate vs. 0.4 tsp of Carbonate to raise the Alkalinity 1 milliequivalent (mEq) / or 2.8 dKH in 10 gals. Weight wise, is it is 3 grams vs. 2 grams.

Bicarbonate, due to that H, has less impact on pH than Carbonate.
Bicarbonate is mostly for raising the Alkalinity along with pH maintenance, while Carbonate is for raising the Alkalinity and pH.

Carbonate used only by itself should only be used if you have a low pH and Alkalinity. If it's to buffer up the Alkalinity, Bicarbonate is better.

Generally in a healthy/balanced reef aquarium where excess CO2 is not being produced or introduced (such as with a Calcium Reactor), a Bicarbonate is the better choice for an ionically blended bicarbonate with other elements in ionic balance such as SeaChem/AAP Reef Builder, NOT an economy Soda Ash Sodium Carbonate.

Recommended Product Resource (sponsors this hobby with websites such such as this):
SeaChem/AAP Reef Builder

Sodium (Na+) more or less accumulates over time, as does the SO4 and Chlorides from non-ionically balanced use of calcium supplements, alkaline buffers, and minor/trace elements. This is why water changes are often needed to keep the chemistry in balance even though specific gravity/salinity is "spot on". Hence my recommendation of the AAP Balling Method or ionically SeaChem supplements.

It is common for the pH to drop over night, especially if the alkalinity is less than 8 dKH. This pH drop is from animals and plants giving off CO2 at night. The reason why it may not hold at a lower Alkalinity is also a night thing of animals and plants "leaching" out things more so, which can have a greater impact on the Alkalinity and pH as they yield acids.
A common limnological[1] term for Alkalinity is ANC ("Acid Neutralizing Capacity"). These affect the pH and Alkalinity. Although it's not often heard of in the aquarium keeping hobby, there's also Acidity, BNC, ("Base Neutralizing Capacity"). It's the opposite of Alkalinity.

Recommended discussion:
Sodium Carbonate vs Bicarbonate; from Manhattan Reefs

References:
[1] "Limnology": The scientific study of the life and phenomena of fresh water, especially lakes and ponds (Adj. limnological - of or relating to limnology).

TRACE/MINOR ELEMENTS

Many trace and some minor elements are not depleted at the same rate as alkalinity and calcium. In my experience not every reef or even marine fish/FOWLR aquarium is the same when it comes to depletion of trace, minor, or major elements.
There is also disagreement among many with what is a minor, trace or major element with websites such as "Live Aquaria" calling Strontium a major element, where as based on its percentage it clearly falls into the category of minor or trace element.

SEE THE LIST BELOW FOR THE MAKE UP OF THE OCEAN:

• Chloride- 55.03%
• Sodium- 30.59%
• Sulfate- 7.68%
• Magnesium- 3.68%
• Calcium- 1.18%
• Potassium- 1.11%
• Bicarbonate- 0.42%
• Bromide- 0.19%
• Borate- 0.08%
• Strontium- 0.04%
• Fluoride- 0.003%
• Other- less than 0.001%

Regardless of what we call each element, it's important to keep your reef or even fish only marine aquariums as close to natural percentages as possible. Although we often find keeping Calcium slightly higher works to our advantage in the closed system most any marine aquarium is in reality.


For this reason, we need to find a method, which works best for us AND our aquarium, not what seems like the method de-jour of the day. As well, just because something might seem more complex, does not necessarily make it better either. So, if you are a beginner, do NOT feel pressured by the so-called pros in many forums, which insist that it's their way or the highway (this is also not to say their method does not work, only that often these over involved methods do not work any better than more simple methods).

As noted earlier, also be careful of popular economy methods, which use bulk Soda Ash Sodium Carbonate and Calcium, then leave out elements, which often get used in conjunction at similar rates such as Magnesium and Strontium. This is still why I prefer the SeaChem or Complete Balling Method over the Economy dosing, Calcium Reactor, or Kalkwasser methods.



Here are a few key Minor/Trace Elements:

• Strontium: Many marine organisms use strontium in the development of their skeletons. Depletion results in poor growth rates in both hard corals and coralline algae.
  Strontium is provided by SeaChem/AAP Reef Builder and Reef Advantage Calcium in ionic balance, which generally replenishes the Strontium to the correct balance. As well the Balling method naturally replaces the correct balance of Strontium in step 3 if this generally simple method is followed correctly. Strontium is also replenished with the use of a calcium reactor, but not as often in correct ionic balance. It is NOT replenished with the Kalkwasser method or the economy methods without supplementations and often then ionic balance is NOT achieved from my experience.


• Magnesium: Magnesium, is partly responsible for the regulation of pH and the formation of your invertebrates' skeletons. However, while a large percentage of saltwater (more than calcium), it's used at a much slower rate than calcium or strontium.
  Generally if SeaChem/AAP Reef Builder and Reef Advantage Calcium are used OR the complete Balling method, supplementation is NOT necessary.
  
  Recommended Resource if needed:
  SeaChem/AAP Reef Advantage Magnesium


• Iodine and Iodide: - Iodine is essential for the health of many soft corals such as Xenia and may also have antibiotic properties in stony coral aquariums. Iodine may also enhance stony coral coloration.
  Iodine often is rapidly oxidized in a marine reef aquarium (not so much a marine fish aquarium).
  I have found additional supplementation is necessary even with use of the before mentioned SeaChem/AAP products or with Calcium Reactors, Kalkwasser and most certainly economy bulk methods. However, less supplementation (if any) is needed with the Complete Balling Method.
  
  Recommended Resource:
  SeaChem/AAP Reef Iodide


• Iron: Iron is used by photosynthetic invertebrates and plants as it provides added nourishment to the photosynthetic cells. Lack if this minor element can result in poor coloring, growth, and expansion within these organisms.
  Generally supplementation is not required with normal water changes and/or the use of the Complete Balling Method.



• Molybdenum: Molybdenum is trace element known to aid the biological processes of many of the beneficial strains of bacteria.


• Other/General Trace Elements; There are many more trace elements as per my earlier list (which itself is not a complete list). Generally with products such as SeaChem/AAP Reef Trace or the Complete 3 Step Balling Method and along with water changes with a quality marine/reef salt mix, these are replenished.
  SeaChem/AAP Reef Trace includes the before mentioned Molybdenum too.
  
  
  Of course starting with a good premium reef salt mix is important as well.
  I recommend Tropic Marin Pro Reef Mix from Germany, although there are many other good/viable reef capable mixes available as well (& many not so good too).
  
  Recommended Resources:
  *SeaChem/AAP Reef Trace
  *AAP Bio-Calcium Original Complete Balling Set; Parts A/B/C.
  *Premium Tropic Marin Pro Reef Sea Salt from Germany

TO SUM IT UP:

The marine aquarium has to have some basic chemistry understanding to have a successful tank. There are a handful of methods, which use different dosing methods, based on science and budget. The most popular method used is different between different groups/nationalities of reef keepers. While there might be different successful ways to keep aquariums, with many examples, there are methods, which have been proven to be more successful than others, when looking at the details of the tank health.
Keeping a reef tank as close as possible to natural ocean water conditions has always been the marine keepers goal. With the addition of dosing a third part of trace minerals, which help keep an ionic balance, this really is the closest to natural sea water any aquarium keeper can keep. These minerals listed in this Reef Chemistry Article and the suggestions on how to maintain, really are the best current professional advice anyone can take and apply to their reef tank.


Other Recommended Reference & Product Sites

PUR or RQE, YouTube Video Fail- Guide to lighting a planted tank


Saltwater Aquarium Information; Basic to Advanced


Aquarium or Pond UV Sterilization



AquaRay Ultra Premium Aquarium LED Lights
Highest in PUR, The ONLY LED with an IP67 rating or higher for water proofing along with a full 5 year warranty to back them up! Why purchase brands without this rating such as the Finnex, Current, or Fluval only to be essentially placing an electronic light emitting device over your humid aquarium with little or no guarantee? In the long term, you WILL PAT MORE!




TMC Premium Fluidized Sand Bed Bio Filters

Premium, second to NONE Aquarium Bio Filters, that with Oolitic Sand also maintain essential marine aquarium calcium levels, alkalinity, & electrolytes that are important to ALL Marine life, Goldfish, African Cichlids, Livebearers & more



San Francisco Bay Brand Seaweed Salad

"Seaweed Salad" is much more nutritious than spinach and lettuce. This product is recommended for all saltwater Damsels, Clownfish, and especially Marine Angels and Tangs






Hydor Smart Wave Controller
• Promotes a healthy reef aquarium or similar aquarium environment where wave action is desired by recreating natural currents found in nature
• Synchronous program for currents typical of barrier reefs and alternate for tides




TMC Advanced Venturi Saltwater Protein Skimmers

A High performance, quality protein skimmer incorporating a patented venturi injection system which optimizes the perfect mixture of fine air bubbles and water and ensures intensive, efficient skimming and the removal of proteins and other harmful toxins (waste) from the aquarium.