With out a doubt, marine aquariums should be filled with natural sea water obtained a couple of miles offshore, to steer clear of coastal pollution. This isn’t so simple to do for your self, but it could be bought from dependable dealers.
An economic substitute for big quantities of sea water could be made artificially. The ingredients for it are as follows:
10 gallon – Soft water
45.5 oz – Common salt (sodium chloride)
0.2 oz – Potassium nitrate
l.5 oz – Potassium chloride
10 grams – Sod: acid phosphate
2 oz – Calcium chloride (dry)
5 grams – Ferric chloride
8.75 oz – Magnesium chloride
0.5 gallon – Natural sea water
11.5 oz – Magnesium sulphate
0.5 oz – Sodium bicarbonate
The above formula has been included mainly for interest. A a lot simpler technique would be to buy the essential salts already compounded which only need the addition of water. Most of the big suppliers of aquariums and equipment will stock these salts.
When adding water to replace the loss caused by evaporation, usually use distilled water. Keep in mind that the mineral content of the water isn’t reduced by evaporation.