Saltwater
A Brief Introduction to the Saltwater Aquarium
(From The Aquatic Critter's Handout, updated March, 2002)

• Introduction

• The Aquarium

• The Stand

• The Substrate

• The Water

• The Decor

• Necessary Equipment

  • Filtration

  • Protein Skimmer

  • Test Kits

  • Heaters and Thermometers

  • Lighting

  • Hospital Tank

• Initial Setup

• Aquarium Water Quality

  • Reef Aquaria

  • Fish Only Aquaria

• Critical Levels

Introduction
This handout is not intended to be a comprehensive approach to maintaining either a saltwater aquarium or specific marine species. It is a brief overview primarily directed to those of you who are unfamiliar with marine aquariums, but are contemplating a move in that direction. For further, more detailed information we highly recommend the following books for both beginners and experienced hobbyists:

• The Book of the Marine Aquarium; Nick Dakin; Tetra Press
• Successful Saltwater Aquariums; John Tullock; Coralife

The Aquarium

• The aquarium should be as large as possible. When considering the size of the tank, remember the principle that "large is good, but bigger is better." The larger the volume of water, the more inherently stable it is in terms of water quality. Further, a larger aquarium provides more versatility and allows a greater species selection. We do not recommend anything smaller than 30 gallons other than for true reef tanks.
• Surface area is of primary importance. A tall aquarium (i.e., hexagon, pentagon), lacking in proportional length and width, regardless of total gallonage, does not provide an adequate volume to surface area ratio for oxygen, carbon dioxide exchange.

The Stand

• The stand should be made of a non corrosive material such as wood which has been treated with a water proofing agent.

The Substrate

• The substrate should be a calcium carbonate medium. Calcium carbonate serves to buffer the aquarium water to the proper pH and replaces natural trace elements as they are depleted.
• Silica sand and crushed or fragmented shell have a high soluble phosphate content. Further, silica sand will compact, creating anaerobic zones. Neither should be used in a marine aquarium. Suggested substrates are crushed coral or argonite sand.

The Water

• With the volume demands placed on municipal water supplies, tap water quality is, at best, questionable in its capacity to sustain marine life for prolonged periods.
  • (Hans Baensch, Marine Atlas, Tetra Press, 1994, page 50),
    "In older literature dealing with marine aquaria, tap water was not considered very important. When the salt mix was correct, the make up of the water was all right. I myself wrote, "tap water and sea salt equal seawater." (1974) This can no longer be said, largely because of pollutants now found in the ground water. Higher nitrate, pesticide, phosphate, and silicic acid levels, among others, have contributed to the significant deterioration of our tap water over the last 15 years. Many hobbyists have to treat their tap water before they can use it in an aquarium."
  • (Nick Dakin, The Book of the Marine Aquarium, Tetra Press, 1992, page 83), "Generally speaking, any reputable salt mix can be dissolved in household tap water to produce a satisfactory solution, ... One word of caution, however, tap water may contain undesir- able impurities in the form of nitrates, phosphates, sulfates, etc., and you may have to purify household tap water using a deionizer or reverse osmosis unit. Many advanced aquarists do this as a matter of course, if they are keeping delicate invertebrates and fish, and it is a practice highly recommended to all marine fishkeepers."
  • (Julian Sprung, Aquarium Fish Magazine, June, 1996, page 46), "The composition of the water used to make artificial seawater significantly affects its quality. Tap water and well water vary in their chemical attributes, and may compromise the quality of artificial seawater when the source of freshwater is contaminated with heavy metals, nitrate, phosphate, organic compounds or toxins. To avoid adding unknowns with the water, it is best to purify it with reverse osmosis and/or deionization systems."
  • (John Tullock, Successful Saltwater Aquariums, Coralife, 1994, pps. 47-48), "Strangely, aquarists do not often give thought to the quality of the fresh water they use to prepare synthetic seawater, and most use plain tap water. I would recommend strongly against this, as, unfortunately, municipal tap water and well waters are frequently unsatisfactory for aquarium use. This is due to the presence of pollutants that, while not deemed harmful for drinking purposes, can cause problems in the marine aquarium. Algae nutrients such as phosphate and silica, toxic metals such as copper, and a host of other compounds may all be found in "pure" tap water. I recommend that all water used for the marine tank be purified in some way."
• Tap water can be purified by two methods; reverse osmosis and deionization.
• While the process of reverse osmosis produces an end product water quality which is dramatically improved over tap water, it has several disadvantages. The production process is a continual, drop by drop procedure which requires a collection reservoir. Maximum capacity for most household units is between 5-25 gallons per day water per day. And, lastly, for each gallon of end product water produced, 4-5 gallons of waste water are generated.
• Deionization is an on demand process which produces water up to 10 TIMES PURER than reverse osmosis. All that is left is the "wet." The downside of deionization is its expense.
• With over 10,000 gallons of combined fresh and saltwater aquaria, our personal assessment of Nashville tap water quality is that it is of inadequate quality for the long term survival of anything other than the hardiest of species. So firmly do we believe this that we have invested several thousands of dollars on a custom designed deionized water system to supply all of our marine and selected freshwater aquaria.

The Decor

• The habitat you provide your fish and/or invertebrates should simulate their natural environment as closely as possible. This serves to eliminate, or at least substantially reduce, stress. An animal which is experiencing continual stress becomes weakened and thus its immune system is less able to resist disease.

Necessary Equipment

• The marine aquarium MUST have more efficient biological, chemical and mechanical filtration than a fresh water aquarium. Water quality is the key to a successful marine experience. Be prepared to spend as much on filtration as you did for the aquarium and stand.
• An undergravel filter provides inadequate biological filtration for marine reef aquariums, but will suffice for marine fish aquariums:
  1. The comprehensive addition of live rock in a reef aquarium will create too many "dead" areas for a sufficient biological process to take place using an undergravel filter. 
  2. Detritus, which is generally rich in undesirable nutrients, becomes trapped beneath the undergravel filter plate, thus raising the nitrate to an unacceptable level for most reef animals. The nitrate level, with appropriate bi-monthly water changes should be kept below 60ppm for marine fish aquariums.
  3. The fine substrates used for marine reef aquariums is too fine for use with an undergravel filter.
• Power filters incorporating biological, chemical and mechanical filtration into their design will provide ACCEPTABLE filtration for lightly populated aquariums up to 55 gallons.
• Eheim canister filters provide EXCELLENT biological, chemical and mechanical filtration combined with minimal maintenance both in terms of frequency and expense. Models are available for aquariums up to 250 gallons.
• If canister filtration is the only form of water circulation being provided, the aquarium must be equipped with a supplemental aeration device. Canister filters are closed systems and, given the density of saltwater, cannot provide sufficient oxygenation.
• Trickle (wet/dry) filters currently provide the most commonly used, most efficient mode of biological filtration. They are available in varying sizes to accommodate aquariums up to 400 gallons. Manufacturer specifications will define individual model capacity and pump requirements. Aquariums utilizing trickle filters should also be equipped with an appropriately sized mechanical filter to provide more efficient particulate removal and to create a current within the aquarium.
• Algal turf scrubbers, one of the latest major innovations in aquarium filtration, has as great an impact on enabling the aquarist to simulate the natural marine environment as did the conversion from undergravel filtration to wet/dry.

The concept of macro algae based water purification technology as developed by Dr. Walter Addey, Director of the Marine Systems Laboratory of the Smithsonian Institute, is amazingly simple. Through the natural process of photosynthesis water pollutants (organic compounds) within the aquarium are removed as nutrients for the algae. The by-product of photosynthesis is life sustaining oxygen.

• A protein skimmer is a crucial inclusion to all saltwater systems, particularly reef aquaria. Tropical reefs, the natural domain of most saltwater aquaria species, are virtually devoid of nutrients (organic compounds). The function of the protein skimmer is the removal of dissolved organic substances from the aquarium prior to their being biologically broken down, producing ammonia and nitrite before being converted into less harmful nitrates.
• All skimmers operate on the same principle. Tank water is mixed with very fine air bubbles, creating foam within the skimmer. Proteins and other organic matter dissolved in the water tend to collect on the surface of the bubbles of foam. As the foam builds up, it rises to the top of the skimmer, spilling over into a collection cup, eventually filling the cup with a greenish brown residue which is periodically discarded. The amount of waste removed by these units can be considerable, and their contribution to long term success with fish and invertebrates is second only in importance to good biological filtration.
• The evolving theory regarding protein skimming is that it is being used too extensively. Proponents of this theory maintain that foam fractionation (skimming) is indiscriminate in what it removes. Consequently, desirable compounds, primarily trace elements, are being simultaneously removed. To compensate for this, a protein skimmer should be allowed to operate at its maximum capacity for several days. Once the amount of organic compounds being removed stabilizes, the skimmer can now be used intermittingly

Test Kits

• Each aquarist, freshwater or marine, should own and be proficient with the test kits required to monitor water quality. It is an accepted fact that with a marine aquarium, marginal or poor water quality will result in stress, disease and probable death.
• The kits required are:
  • pH/alkalinity
  • Ammonia 
  • Nitrite 
  • Calcium (reef only)
  • Specific Gravity
  • Phosphate (reef only)
  • Nitrate
• The combined cost of these test kits is approximately $100. Saltwater fish, on the average, cost $15 to $175 apiece. The choice is yours where you want to spend your money, but without conscientious monitoring of water quality, you will not have a successful marine experience.

Heaters and Thermometers

• Submersible heaters mounted horizontally above the substrate provide for the most efficient heat dispersion. Wattage requirements are 4-5 watts per gallon.
• For aquariums of 55 gallons or greater capacity we recommend using two heaters. This allows for a more even distribution of heat and back up security in case of heater failure.
• In aquaria housing invertebrates and, more importantly, anemones, heater covers should be used to prevent the inhabitants from being burned by the heater elements.
• Two thermometers mounted at opposite ends of the aquarium provide for more accurate temperature measurement. One should be mounted just above the substrate and the other at the top of the waterline.

• Your aquarium lighting system must accomplish two distinct tasks. First, your lighting system must have the ability to sustain life and the life functions of each of your aquarium inhabitants. Second, the artificial light must make your aquarium appealing and visually enjoyable to you the viewer.
• For a fish-only, smaller aquariums (55 gallons or less) a single strip, full spectrum fluorescent tube is sufficient. For larger aquaria, twin tube strip lights are recommended. In reef applications the amount of energy to maintain corals and anemones is much greater than standard wattage fluorescent lamps can provide. The required lighting types are, in typical order of least to most intense energy, VHP, Power compact, and Metal Halide. 

• A 20L or 30 gallon bare bottom hospital tank, equipped with heater, thermometer, power filter, air pump and a glass canopy, is a must.
• Medications introduced into the main tank can have the following detrimental effects:
  • Antibiotics disrupt the biological filter and deplete the oxygen level.
  • Copper medications are lethal to invertebrates.
  • Many anti parasitic medications are lethal to invertebrates and, being dye based, will stain aquarium decorations.
• The main tank should only be medicated when several fish exhibit symptoms of illness.

• Thoroughly wash the substrate and place it in the aquarium.
• Partially fill the aquarium with temperature regulated water.
• Add sufficient dechlorinator for the total gallonage of the aquarium, if you are not using filtered water.
• Install heaters. DO NOT PLUG IN.
• Install filters per manufacturer's instructions. DO NOT PLUG IN.
• Add decorative items.
• Add the prescribed amount of marine salt.
• Finish filling the aquarium.
• Plug in heaters and filters.
• Allow the aquarium to run for a minimum of 72 hours to allow for accurate water chemistry readings. Acceptable parameters for the initial introduction of fish are:
  • Temperature 75-80°F; stable
  • pH 8.1 - 8.3; stable
  • Specific Gravity 1.021 -1.024; stable

Aquarium Water Quality

Critical Levels

• SPECIFIC GRAVITY:
  The specific gravity (or density) is the ratio of the amount of total dissolved salts in water as compared to pure water. Pure water has a specific gravity of 1.000. As more salts are added to the water, the specific gravity increases.
• pH:
  A measure of acidity or alkalinity; pH ranges from 0 - 14, with 7 as the neutral point. Above pH 7 water is alkaline; below 7 it is acidic.
• ALKALINITY:
  A numeric measure of the resistance of water to a change in pH as acid is added.
• AMMONIA:
  The most toxic product formed in water. Sources of ammonia in the aquarium water are the fish (respiration and digestion) and decaying, uneaten foods.
• NITRITE:
  Toxic intermediary product created in the process of breaking down organic waste products. It occurs between ammonia and nitrate in the nitrification process.
• NITRATE:
  Mildly poisonous end product of the breakdown of nitrogenous waste products in the aquarium.
• PHOSPHATE:
  A salt commonly found in tap water which serves as an algae nutrient..
• CALCIUM:
  A natural salt used by invertebrates in the construction of their shells, skeletons and/or carapace.

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