5
0.1 Introduction
If you ask anyone who has ever kept marine animals if they enjoyed it, they will most always respond with a very positive “YES!” Marine animals themselves offer an intriguing level of complexity not found in any other pet[†]. Keeping marine animals can be an extremely rewarding experience—if the time is taken to learn how to do it right.
This manual is intended to give the novice or experienced marine animal keeper the proper background necessary to set up your first marine tank, or to learn more about the one you already have. Within this manual you’ll find:
· A thorough introduction to the basics of seawater
· The nitrification process and tank “cycling”
· An overview of some of the many fish and invertebrates you can get for your tank
· A description of all of the gear to put into your tank
· Step-by-step instructions on how to assemble your first tank!
0.2 How to Use This Manual
Section 1, “Marine Tank Basics,” covers the bare essentials of every marine tank: seawater and animals! Section 2, “Marine Tank Creation,” covers the equipment that go into your tank, (filters, heaters, etc.), and has instructions on how to assemble your first tank.
This manual is not designed to be read from front to back. If you are a beginner, start in Section 1 and read the sub-section on Seawater, then skip to Section 2 and read about the gear you need to buy for your first tank. Once you have your tank set up, go back to Section 1 and read about what kind of fish to put in it.
An important note to the reader: This manual should not be treated as a “complete” guide to keeping marine animals. There are many factors involved when keeping marine animals, and although this manual may cover most of them, it does even come close to covering all of them. To be successful with marine animals you must constantly be learning more about your marine creatures and their habitat. Don’t stop learning after you read this manual!
Section 1: Marine Aquarium Basics
1.1 Seawater
Water, as most of us have learned, is H2O, two Hydrogen atoms bonded to a single Oxygen atom. H2O by itself is an extremely “sticky” molecule, in the sense that it likes to cling onto other molecules[†]. This stickiness is what allows you dissolve substances in H2O. When you stir sugar into a hot cup of tea, the sugar appears to disappear because the H2O separates and clings onto very small portions of the sugar. When you dissolve something in H2O it is said to be in “solution.”
Seawater is a very complex solution. Substances such as salt, manganates, carbonates, sulfates, nitrates, and many others are present in seawater. In fact, there are so many substances in solution in seawater that the water itself (H2O), makes up only 96% of its content3! A partial listing of natural seawater’s content is provided in Table 1.
Because seawater is the basic element in a marine animal’s livelihood, (for obvious reasons), the marine hobbyist must attempt to provide the highest quality seawater for his or her marine animals. In the following sub-sections I will explain the elements of seawater that the marine animal keeper must be aware of.
Element / Species / mg/L / mol/LH
O
Cl
Na
Mg
S
Ca
K
C
N
Br
B
Si / H2O
H2O, O2
Cl-
Na+
Mg2+
SO42-, NaSO4-
Ca2+
K+
HCO3-, CO32-, CO2
N2, NO3-, NO2-, NH4+, NH3
Br-
B(OH)3, B(OH)4-
Si(OH)4 / 108,000
857,000
19,000
10,500
1,350
855
400
380
28
15
65
4.6
3.0 / 1.07E2
5.36E1
5.36E-1
4.57E-1
5.55E-2
2.76E-2
9.98E-3
9.72E-3
2.33E-3
1.07E-3
8.14E-4
4.26E-4
1.07E-4
Table 1: A Partial Listing of the Inorganic Composition of Seawater3
1.1.1 Salinity and Specific Gravity
The largest substance in seawater, (besides water!), is NaCl (sodium chloride or table salt). When NaCl is dissolved in H2O it is broken up into it’s essential components Na and Cl, and a NaCl solution is said to be formed.
Marine animals expect a certain level of NaCl to be present in their water. This level is commonly referred to as the “salinity” of the water. Salinity by itself is a very difficult thing to measure because of all the other things that are present in seawater along with NaCl. Instead, we measure the specific gravity. Specific gravity is very closely tied to salinity, and is a lot easier to measure.
To measure specific gravity you will most often use a “specific gravity meter” or a conventional hydrometer. Hydrometers are a little bit more difficult to use because they depend on the temperature of the water2. For this reason I recommend you use a specific gravity meter.
An acceptable specific gravity for seawater is between 1.020 and 1.024, depending upon where you are in the ocean1. For your marine tank, it is advised that you keep your specific gravity absolutely no lower than 1.020, and absolutely no higher than 1.025, preferably around 1.022.
Fish and other marine animals are extremely sensitive to changes in specific gravity because they depend on it to maintain their internal osmotic pressure2. For this reason check your specific gravity on a regular basis (every week or so), and do water changes if necessary to restore your specific gravity back to normal. If drastic specific gravity changes are required (more than .004), do it over a long period of time (1-2 days).
1.1.2 Alkalinity
The substances discussed above that are dissolved in seawater alter the properties of the water besides just changing the specific gravity. The substances can also alter the Alkalinity and Acidity of the water. Natural seawater is alkaline.
Alkalinity, by a purely chemical definition, refers to the concentration of OH- ions present in water3. Dissolving a “basic” substance in the water creates these ions. The reasons behind seawater being alkaline is beyond the scope of this text, so unfortunately I’ll just have to leave the reader with this: “Make sure your seawater is the right alkalinity.”
Fish and other marine animals are used to a steady alkalinity of 8.2pH5. You can easily measure this within 0.1pH using a simple pH test kit available at your local fish store. If your pH is too high, you can use a pH lowering product, and visa-versa. Just remember to make these changes very gently over a long period of time. Sudden changes in pH can kill your animals.
Note: If you are having trouble with your alkalinity, try doing a 10-25% water change before you run out and buy pH altering chemicals. Doing water changes is a lot safer, and need to be done anyways!
1.1.3 Temperature
In the ocean, temperature can vary anywhere between 75ºF and 82ºF. For a marine aquarium, it is recommended you keep your tank at a steady 78ºF1. You can easily monitor your tank’s temperature using either a stick-on type thermometer that you affix to the exterior of your tank, or a floating thermometer. The floating type is usually more accurate.
Sudden jumps in temperature, more than 2ºF in one hour, can be very stressful to your fish and other animals. If you are having problems keeping your temperature steady, consider purchasing a better heating or cooling system. (Heaters and chillers are discussed in Section 2).
1.1.4 Nitrification and Cycling
Seawater goes through a complex waste recycling process commonly referred to as the “nitrogen cycle” or nitrification. During nitrification organic waste is decomposed into several different Nitrogen-based molecules by special sets of bacteria and other live organisms. In the marine aquarium it is tricky to strike a balance with nitrification, and the marine aquarist must pay special attention to its maintenance.
Nitrification begins with organic waste: waste produced by plants, fish, etc. Over a brief period of time (1-10 hours), this waste is naturally dissolved into the seawater. One of the molecules that appear as a result of the dissolution is Ammonia, NH4. Anaerobic bacteria then break down the Ammonia into Nitrite, NO2-, and finally into Nitrate, NO3-. This process is outlined in Figure 1.
When you first set up your marine tank it takes about 25-30 days for the nitrification cycle to strike balance after you first put fish in it. In the mean time you can observe sharp increases in your Ammonia, Nitrite, and Nitrate levels. These early days of your tank are commonly called the “cycling” period. (See Figure 2).
During cycling extra care and consideration must be put into your tank. Check Ammonia and Nitrite levels regularly to make sure they rise and then fall back down. Do not put any organism in your tank that can be sensitive to high concentrations of Ammonia or Nitrite (see “Fish,” section 1.2). All invertebrates are extremely sensitive to Ammonia, Nitrite, and Nitrate, so they are out of the question during cycling.
When cycling is complete it is essential you perform a 25-30% water change with your tank. After the water change Ammonia and Nitrite should be virtually non-detectable due to nitrification. Check Ammonia and Nitrite levels regularly. If you ever detect Ammonia or Nitrite after the cycling process is complete, do a 25-30% water change, and re-evaluate your filtration setup. (See “Filtration” in Section 2).
After cycling, your Nitrate level will continually rise. There is no way to naturally combat Nitrate in a closed system unless you are willing to deal with the only organism that eats Nitrate—algae. (Algae has it’s own set of problems associated with it, and is not pleasant to look at, so we will not consider it as an option). In a marine tank, you must frequently perform water changes, 10% every week, and regularly monitor Nitrate, in order to keep your Nitrate levels down.
Ammonia, Nitrite, and Nitrate, as you have probably guessed by now, are bad for marine animals. Any of these substances in high quantities can ruin an otherwise healthy tank. It is good practice to regularly monitor them and perform water changes as needed. See Table 2 for a listing of acceptable Ammonia, Nitrite, and Nitrate levels.
Chemical \ Application / Fish Only Tank / Invertebrate TankAmmonia / < 1ppm / 0ppm
Nitrite / < 1ppm / 0ppm
Nitrate / < 10ppm / < 0.5ppm
Table 2: Acceptable Levels of Ammonia, Nitrite, and Nitrates (Parts Per Million)
1.2 Fish
In this sub-section I’ll cover popular fish for the beginner, and some fish the beginner should stay away from. For an almost complete guide to picking fish for your marine aquarium see The Tropical Marine Fish Survival Manual in the reference section.
1.2.1 Damsels
Damsels are the perfect fish for the beginner. These fish are very hardy, and can withstand the stress of tank cycling very easily. Damsels are not very picky eaters either; they will eat most flake foods, (but still love an occasional frozen brine shrimp treat). Best of all, damsels are very cheap!
The downside to damsels is that they can be very aggressive, especially males. Damsels have a tendency to guard territory they believe is theirs, and challenge other fish for food. Fortunately damsels rarely manage to damage any other fish, as they don’t have any teeth, so their aggressiveness plays off as more harassment than it does fighting.
Despite their aggressiveness damsels are still a good pick for the beginner. In a large tank (55 gallons), 3-4 damsels won’t be too bad.
1.2.2 Mollies
Mollies are a freshwater fish that you can acclimate into saltwater. Some people prefer to cycle their tanks with mollies because they are so much cheaper than regular saltwater fish. Although this may be a less-threatening way to get started with your marine tank, your author does not recommend this method.
If you do decide to start your tank with mollies, you can acclimate them to saltwater by slowly increasing the salinity in their environment over a 6-8 hour period5. Bear in mind that if you decide to get any real saltwater fish later they will never cease harassing the passive mollies.
1.2.3 Clownfish
Clownfish are not recommended for cycling a tank if you are a beginner, even though they are a fairly hardy fish. Once your tank is done cycling, however, these are a great fish to add to your tank.
Clownfish can be very territorial towards non-clownfish, so pick your species carefully if you decide to get clownfish. Ask your pet storeowner for compatibility.
1.2.4 Triggerfish
Triggerfish, (Huma-huma, Black Trigger, Bursa Trigger, etc), can be used to cycle a tank if done cautiously. Triggerfish can be very aggressive sometimes, (as they are carnivorous), so be careful if you decide to setup a tank with triggerfish. A general rule of thumb is to never place a fish smaller than a triggerfish in the tank with it, if you want to keep it!
1.2.5 Blennies and Gobies
Small fish in the Blenny and Goby class are very passive, however they are not hardy enough to withstand the cycling process. Add these small fish to your tank once it’s done cycling.
A word of caution: Some species of Gobies are extremely picky eaters, especially the Mandarin and Dragonet Goby. They are not recommended for the beginner.
1.2.6 Tangs
Tangs, or Surgeonfish, are hardy, fairly passive, and algae-eaters. If no algae is present in your tank you need to feed them leafy green plants like lettuce to keep them fed.
1.2.7 Fish to Avoid
If you are a beginner, you must immediately walk away from Angels, Butterflies, Pipefish, Seahorses, Filefish, Mandarin Gobies, Dragonet Gobies, and Eels, and distrust any pet storeowner that tells you otherwise. Use common sense, if a fish has a highly specialized diet (or if you don’t even know what it’s diet is), then stay away from it.
When picking out fish in the pet store, you also want to stay away from fish that look sick, are too shy, or would potentially cause harm to any other fish or animals you have in your tank already. To test if a fish is a good buy, have the pet store owner try and feed it. If it takes too long to notice food or is completely uninterested in it, then chances are it’s going to be difficult to feed or is sick.