
MARINE AQUARIA 

More water than is required to fill the aquarium should be prepared so 
that a part may be kept in reserve, which, in a cool place, will not deter- 
iorate but improve in quality and in fitness for use in case of necessity, 
which may happen to the novice. 
Hyprometer. A hydrometer or specific gravity bulb is not abso- 
lutely necessary but is useful. Seawater has a specific gravity of 1.023 to 
1.031, which means that a volume equal to one cubic centimeter is approxi- 
mately .027 grams heavier than the same volume of freshwater of the 
same temperature, customarily taken at 10°C. or 50°F. Should the 
hydrometer sink below this point, then the water is not sufficiently saline, 
or should it rise above,it is too concentrated. Having established the degree 
of salinity of the water when the aquarium has been filled, its maintenance 
is simple; evaporation to produce concentration is only the wellwater, 
which may be filled in, or should changes occur to affect the degree of 
salinity, a part of the water may be siphoned and some of the reserve 
water added, to again establish the correct balance. This very rarely or 
never occurs. 
Before the living inmates are introduced, the aeration should be 
operated for some time, that the water will be charged with air, to revive 
the animals after their exhausting journey or from other disturbances 
which may affect their survival. 
TEMPERATURE. With proper aeration the temperature of the water 
does not seriously affect the inmates. Those of the household, of 70°F. 
to 80°F. in the summer, are not injurious, if the air supply is sufficient; 
for which reason the aeration should be more considerable in warm than 
in cool weather. The activity of the animals also increases with the tem- 
perature, whereby they liberate more carbonic acid gas and require a cor- 
responding increase of oxygen for their comfort. 
Marine Aquarium Prants. The growth of plants in the marine 
aquarium for other than ornamental purposes has never been satisfactorily 
accomplished. No dependence can be placed on them to serve as oxygen- 
ators; for, though they are of most exquisite and delicate forms and 
beautiful colors, they are all of the lower order of cryptogamous plants 
which rank as very indifferent generators of oxygen. 
Marine Frora. These marine cryptogams or algals are all non- 
flowering, cellular plants, which may be classed by their colors, as this 
very nearly corresponds with the botanist’s classification based on their 
methods of reproduction. The lowest and simplest forms, Chlorospermez, 
are bright or grass-green in color, the next higher, Melanospermez, olive- 
colored, and the highest forms, Rhodospermee, are red in color. All have 
a wide range of distribution in America and Europe, and consist of arctic, 
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