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9. Mixing Saltwater
Mixing saltwater and adjusting salinity are critical to the saltwater aquarium environment. Salinity is a measure of the specific gravity of the aquarium water. Purchase a good, reliable hydrometer to measure the salinity of your water. Your local dealer may be able to calibrate your hydrometer against a refractometer for the most accurate readings at home. Following the steps outlined below will ensure accurate results for your new tank and the monthly water changes that follow.

Solution 13, Saltwater Aquarium Maintenance, for detailed information about regular water changes.
Mixing in a new aquarium without livestock:     Water Changes with livestock:

A new system should be run with freshwater prior to adding salt. This test run allows time to check for leaks, locate equipment problems and avoid wasting salt.

After all system equipment is installed and running properly, the tank has been filled with freshwater and dechlorinated, salt can be added slowly and mixed directly in the tank. Small amounts of salt are added at several intervals and allowed to mix thoroughly before checking salinity with a hydrometer.

Salinity can be checked while water is still cloudy, but there should be no undissolved salt at the bottom of the tank. Continue adding salt until the salinity measures 1.020 on the hydrometer. Once the proper salinity has been reached, allow the tank to totally clear and reach a constant temperature of 76-78°F. Allow 24 hours for settling and temperature compensation.

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Once the tank is clear and the temperature is correct, adjust the salinity to 1.022 by adding small amounts of salt. If the salinity measures above 1.022 at a temperature of 76-78°F small amounts of water will have to be removed from the tank and replaced with dechlorinated freshwater. This may have to be repeated until the salinity is correct.
Turn off the filtration equipment and remove 10-25% of the tank water by siphoning with a gravel cleaner. Keep track of the number of gallons of water removed by siphoning into measured buckets. Follow the procedure below to mix and replace the water removed from the tank during cleaning and siphoning.

1) Check the temperature of the water in the aquarium.
2) Using a non-toxic container, (one used only for the aquarium), add 5 gallons of water at the same temperature as the aquarium.
3) Add
Vibrant Sea Salt Mix saltwater mixture to the container at approximately 2.5 cups per 5 gallons of water (about 1/2 cup per gallon of water.) Add dechlorinator and mix thoroughly. No crystals should be left undissolved.
4) The longer ahead the water is made the better. The temperature must be the same as the aquarium water.
As long as all the salt is dissolved it is safe for use in about 15 minutes.
Vibrant Sea Salt Mix is a high grade saltwater mix that contains all of the major elements found in sea water and it mixes quickly. Buffers are added that may give a slight cloudiness that will clear quickly. Aquavitro Salinity is sold only at our local store.
6) Once the new saltwater has been added to the tank, clean and restart all equipment. Always re-check the salinity.

• Synthetic Sea Salt
Vibrant Sea Salt Mix, 60# bag - Creates the perfect environment for delicate marine life, as well as supporting enhanced biological filtration. We also add extra calcium and magnesium to benefit corals and other invertebrates. Tests show that ONE SEA achieves the correct salinity, pH, calcium concentration and magnesium concentration when rehydrated as directed.

• Do a 25% water change monthly or a 10% water change twice a month. Remember to dechlorinate the water and adjust it to the same temperature as the aquarium water.

• The pH should be 8.2. High quality salt such as
Fritz RPM has added buffers and with proper water changes, pH should be stable. Aquavitro Salinity is sold only at local authorized dealers, like our local store. For other high quality salts available online, see Vibrant Sea Salt Mix. However, if water changes are being done and pH is a problem, use Marine Buffer or Reef Builder for reef tanks by SeaChem. Further information is available on water parameters in the Log Sheet section.

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• Always add a high quality dechlorinator anytime tap water is added to the tank. AquaLife Complete is an excellent product that not only dechlorinates but adds important elements to maintain slime coat integrity and reduce stress. AquaLife Complete also detoxifies chloramines if they are present.

• Chloramines
Municipal water treatment plants in some areas, in order to make water safe for human consumption, add chemicals to the water that can kill your fish. If chloramines are present in your tap or tank water, use
AquaLife Complete.

• A word about tap water . . .
Tap water is prepared for human consumption and is not safe for use in aquariums. Chlorine and fluoride are added to tap water for the protection of humans but will kill your fish and wipe out the beneficial bacteria in filters. Water conditioners are inexpensive and neutralize these toxic compounds. Good water conditioners bind metals and enhance the slime coat barrier of fish to help prevent disease. Reverse osmosis or ion exchange water significantly reduces excess algae growth in reef tanks and saltwater fish tanks.
Reverse Osmosis units from Aquairum Life Support Systems are among the best money can buy. These units produce soft, phosphate-, silicate-, and nitrate-free water. When using reverse osmosis water, remember to use AquaLife Complete to replace essential elements back into the water. Pre-treated water can be purchased at better aquariums stores. For small water requirements this is sometimes convenient.

Special Note!

As water evaporates from the aquarium, the salt concentration of the remaining water increases. Salt does not evaporate. Always add dechlorinated freshwater to top off the tank.


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