Seawater
As you need to mix commercially prepared ’sea-salt’ with large amounts of tap water, it is advisable to acquire a large, new, plastic dustbin in which the materials can be mixed. However, you will not need to do this immediately, because the process can be started in the tank.
First, calculate the volume of your tank (length x breadth x depth, in centimetres or inches, remembering that 1 litre = 1,000 cm3 and 1 gal 275 in3). You will then be able to pour in the appropriate amount of special salt compound. (The gravel or coral can be ignored at this stage.) Use only specially prepared for aquarium use, not ordinary. Sea-salt sold for cooking purposes.
Install the heater and thermostat, and a suitable thermometer in the tank with normal cold tap water which has been allowed flowing for a few minutes to remove any water which might have contaminated with copper dissolved from the pipes. Pour the water into the tank from a plate or bowl.The tank can be filled to within 4cm (11/tin) of the top.
Switch on the heaters and air pump and, over the next:-hours, check that the temperature has established itself at 24-2(75-79°F). Meanwhile, the aerator will have driven off dissolve-±toxic chlorine gas. Adjust the thermostat if necessary to get temperature right. The sea-salt can now be added gradually with a chart or table with the salt, giving the amounts require per liter or gallon of tap water, and you must adjust this accordant the volume you have calculated. Don’t put in the full amour hold back about 10 per cent. Stir the water thoroughly as you a: the salt, and leave it for another 24 hours to dissolve properly.
Now you will need a simple hydrometer, to check the satin. Accurately. This is a floating device which gives a reading of density, or specific gravity (SG), of the water. Pure water hiss of 1.00, while the SG of natural seawater is 1.020 to 1.025. which is a standard aquarium temperature of 25°C (77°F). In the aquarium, .there is some benefit in keeping the SG low and other disease-producing organisms, and 1.020 is about right figure to aim for (for the more specialized needs of marine invertebrates, an SO of 1.025 is better). If you find that it is low, stir in more salt gradually until you have achieved proper level. It is easiest to make these fine adjustments if it is dissolved in water first and then added as a concentrated solution. If you have miscalculated and made the water too salt remove some and replace it with fresh water until you have correct SG.