When the uninitiated hear about saltwater aquarium care, their general reaction is “No way: saltwater tanks are too hard!”
The fact that you are reading this article means you either disagree or are willing to embrace the challenge in exchange for the joy of keeping some of the world’s most fascinating and beautiful creatures.
The truth, that I hope you have learned, is that this hobby is not nearly as intimidating as it appears. In fact, the aquarium hobby can be relatively simple, or as complex as you care to make it.
The focus of most of our articles this year has been about ways to simplify the hobby, breaking it down into understandable segments to help you succeed. Our usual disclaimer applies: this article is meant for the average hobbyist, not prep work for graduate level biology study.
We may call it saltwater but, in reality, seawater is made up of numerous minerals, most of them only in trace amounts. Salt, as in sodium chloride, only makes up a portion of the molecular soup that is natural seawater. It would require a chemistry degree or some serious studying to truly understand the intricacy of what makes up the ocean’s waters, but we’re not going there. Instead, we’re going to break down the subject of what to dose in your aquarium and how to do it.
There isn’t one right way to be successful in the aquarium hobby. There are, in fact, many paths to keeping a happy, healthy aquarium. Today we will cover are a few basic ways to keep your water similar to what is found in nature. Your application may vary, but the principles shared here have worked for a great many hobbyists.
The most important way to dose your tank is to perform regular water changes. In addition to removing wastes, fresh saltwater also brings an influx of minerals that have been depleted back into the aquarium. This may not be enough on its own, but it is still the most important thing you can do to keep a healthy aquarium.
Now, before you pour anything into your tank, it is important to understand what you are adding and how much you need to add. You can easily throw off the parameters in your aquarium if you start indiscriminately adding things to your water. We commonly see this happening with alkalinity buffers.
New hobbyists, instructed to keep their pH at 8.4, repeatedly add buffer to their aquariums to maintain ideal pH. Instead, the alkalinity in the tank ends up skyrocketing, threatening the health of the entire system. The truth is, pH fluctuates throughout the day and is relatively safe between 7.9 and 8.4. Overdosing alkalinity and other additives can easily be avoided by simply testing first.
So, if the first step in dosing is to test, what should we test?
To keep things simple, I recommend at least testing for calcium and alkalinity. I strongly suggest magnesium as well. This is, of course, in addition to testing for water quality parameters like nitrate and pH. Test weekly and record the results in a tank journal or log. While not particularly fun, it is necessary if you want to see what effect dosing has on your system. A brand-new system may not need much calcium, but as it matures and corals grow, so will the demand.
After testing, you will know precisely where things are at. Now let’s cover where they should be.
We recommend keeping calcium between 400-450 ppm (parts per million), alkalinity between 8-12 dkh and magnesium around 1300 ppm. While these ranges are acceptable, you should always shoot for stability in each of them. For instance, if your alkalinity is at 9 dkh, you should try to keep it there instead of dosing it up to 12 dkh and waiting until it falls to 8 dkh to dose again. Like most aspects of aquarium upkeep, keeping things stable is one of the keys to success.
It is important to note calcium, alkalinity and magnesium need to be in balance with each other. Without getting overly complex, knowing how to balance these will help you understand how much to dose.
Think of your water as an empty jar. Now, picture your calcium, alkalinity and magnesium as different colored marbles. Only so many marbles can fit inside the jar before they will go rolling over the sides. If you have all alkalinity marbles in your jar, then there is no room for calcium and magnesium marbles, and so on. If your alkalinity is testing very high and your calcium low, your calcium will stay low no matter how much you pour into your tank. In fact, if this happens, you may see it begin to “snow” while you are dosing. This happens because there is no room left in the water for the calcium. Always keep things in balance so that there is enough room for calcium, alkalinity and magnesium: 420 Ca, 9 Alk and 1325 Mag are good numbers to shoot for.
We now know where we’re at and where we want to be. Let’s talk about how we’re going to get there.
The most popular method is to use a two-part dosing system, like ESV B-Ionic or Two Little Fishies C-Balance. The main ingredients are split into two bottles, calcium and alkalinity. Two-part systems are designed to dose all the important minerals in the same ratio they are used in your tank. For most aquariums, this is enough to keep things stable. The more frequently the system is dosed, the more stable conditions will be. It is better to dose small amounts daily than to dose large amounts infrequently.
You should get your parameters as close to the aforementioned numbers as possible when you first begin to dose your aquarium. Then, you can start adding small, equal amounts of part 1 and 2 to maintain the levels. Do not add parts 1 and 2 at the same time. You want the first to mix into the system before adding the second so that they do not react with each other and become unusable.
After a few days, test the calcium and alkalinity again. If they are below 420 ppm Ca and 9 dkh alk, then you will need to add a little more daily (after adding enough to get them back to where they should be). If the calcium and alkalinity are too high, hold off on dosing for a day or two instead. After a few weeks of dosing and testing, you will have gotten a feel for how much you need to dose daily and the task will become less tedious. Remember that as time passes, the aquarium will require more and more supplements to make up for the constantly growing corals and coralline algae.
Even though two-part additives do a very good job of keeping things stable, over time, magnesium and other trace elements may slowly fall. Aquarists with low magnesium often have difficulty with nuisance algae and falling calcium levels.
If you are having trouble maintaining calcium, it is very possible that your magnesium has fallen well below where it should be. I prefer to add a magnesium salt, like Seachem Reef Advantage Magnesium, to my top off water. A few spoonfuls in a 5-gallon jug of freshwater top-off do wonders for maintaining proper levels. I also see positive results by adding a few capfuls of trace element supplements every week or so.
Kalkwasser is an excellent alternative to two-part dosing. With kalkwasser dosing, you dissolve a small amount of kalkwasser (calcium hydroxide) into freshwater that is then slowly added into the aquarium via a drip or through an automatic top-off system. Kalkwasser also has the benefit of raising pH and removing phosphate. When adding kalkwasser through an auto top-off, a Kalkwasser reactor can be very helpful. The downside to kalkwasser: if added too quickly, it can dramatically raise your pH. That said, it doesn’t need to be added daily to be effective.
Now that you’ve got the basics of water chemistry covered, let’s delve into more advanced techniques.
Carbon source dosing may be right for you. Frequent dosing and a discerning eye are required, so proceed with caution. You basically add bacteria to your aquarium that eventually begins to overpopulate the tank. At this time a food source for the bacteria will then be added. The bacteria will feed on the tank’s nitrate and phosphate resulting in a very clean aquarium environment. Now fattened on excess nutrients in the system, the bacteria become coral food or are removed by a protein skimmer.
Many hobbyists discover their systems have such a low nutrient load they must feed their fish and corals more heavily to keep them healthy. This, in turn, creates a strikingly beautiful aquarium, with stunning displays free of nuisance algae.
Three great systems for experimenting with this are Korallen Zucht’s Zeo method, Brightwell’s NeoZeo system, or Prodibio’s Biokit. Each of these systems includes a bacteria source, a bacterial food and some form of amino acid or coral food. Follow the manufacturer’s directions closely, as this is one area where you want to avoid overdosing. Don’t hesitate to contact us if you have any questions.