7/27/2019 Marines Fishes

1/4

Equipment For

The Marine Aquarium

Setting up a marine aquarium poses a rather special setof problems for two main reasons. Firstly, the chemical

nature of sea water is very different from that of fresh

water. Secondly, the sea is in many ways a far morestable environment than fresh water and the majority of

its inhabitants are adapted to make the most of a much

narrower range of conditions.

THE CHOICE OF TANKThe most important point to bear in mind is that salt

water is extremely corrosive; it will rapidly attack any

exposed metal surface, weakening the structure and

more immediately important allowing the toxic

products of metal corrosion to pollute the aquarium.

This determines the kinds of materials which may beused in the construction of a tank. The strength of the

materials used depends upon the pressure to which the

tank is subjected. The pressure within a liquid increaseswith depth but is independent of the other physical

dimensions. Also the pressure acts in all directions it

presses outwards against the sides as well as downwardsagainst the base. A tank which is 10 in (25 cm) deep

will not require thicker glass if it is 36 in (90 cm) long

by 18 in (45 cm) wide than if it is 18 in (45 cm) long by

10 in (25 cm) wide. But any 18 in (45 cm) deep tank

will certainly require thicker glass than any 10 in (25cm) deep tank.

All-glass construction. The all-glass tank, which isessentially five plates of glass bonded together with

silicone rubber adhesive, readily meets the requirements

of non-corrosibility and non-toxicity. For the aquaristwho intends to build his own tank the following points

should be borne in mind. The glass surfaces to be

bonded must be scrupulously clean even traces ofskin oils will impair the strength of the join; care must

be taken to eliminate all air bubbles from the adhesive;

the glass used must be thick enough to withstand thepressureuse in (6 mm) thick glass for depths up to10 in (25 cm) and 3/8 in (9 mm) thick glass for depths

up to 18 in (45 cm). The back and side walls of the tank

can be painted (on the outside) with blue paint, orpanelled with blue plastic, to create an impression of

depth. This has the further advantage of giving the

fishes a greater sense of security. The front of the tankmay be similarly 'framed' to hide from view the base

gravel-filter and the surface of the water. The wholebase area of the tank must be supported by a sheet of

blockboard or plywood of adequate thickness.

The wooden tankThis unusual form of constructhas the advantage of cheapness. Thick marine ply,

(9 mm) thick, is used for the base, back and ends, a

the front is a wooden frame bearing the glass panel. Tply is glued together with resin and pinned. T

structure should be strengthened with wooden rails a

cross members at the top to prevent bowing. Tinterior wood should be sealed with a nontoxic epoxy

glass-fibre-reinforced polyester resin. A glass to re

bond can be effected with a synthetic rubber ma(again surfaces must be clean). After allowing it to d

the tank should be cured with strong salt solution for

7 days. A marine varnish may be applied to the outsid

This type of tank offers the greatest savings to tho

who require a deep tank for the culture of deep-bodfishes such as Moorish Idols, angelfishes and butterf

fishes.

Plastic-coated iron frameThis is a conventionaconstructed tank but the angle iron is coated withplastic to prevent corrosion. It is better to buy a ta

with a nylon-coated frame rather than one with a PV

or polythene coated frame. The seams should be sea

with silicone rubberit is most unlikely that this whave been done by the manufacturer in order

prevent toxins from the oil-based glazing putty frentering the aquarium water. This type of tankexpensive to buy.

Stainless-steel frame In the author's experience,cheap stainless steel frame has ever proved complet

rust resistant; some kind of sealing is essential.

Angle iron frame The angle-iron-framed tank been the basis of the home aquarium for at least seve

years, but because of the extremely corrosive nature

sea water it is quite unsuitable for marine use unless metal is first insulated from direct contact with

water. The tank should be completely stripped dow

the frame sand-blasted and insulated with polyesresin and glass-fibre tissue, and the aquarium th

carefully re-glazed. Thoroughly clean the inside of

tank and seal the seams with silicone rubber.

All-plastic In the smaller sizes up to 24x12x12(60x30x30) these tanks are extremely good valTheir main disadvantage is that clumsy cleaning of

7/27/2019 Marines Fishes

2/4

front panel can result in serious scratching. Against this

and it must be admitted that a scratched panel is a

rebuke to the aquarist rather than the, tankmust be

set non-toxicity, non-corrosibility, low cost and low

weight.

Hoods and covers The tank should have a well-fitting glass cover to keep dust out of the aquarium andto allow condensation and splash to run back into the

water. Hoods are .often made of aluminium, a metalwhose toxicity to coral fishes is rivalled only by copperand zinc. An aluminium hood should be coated with a

suitable primer, painted with a good white undercoat

and given a gloss finish.

SEA WATER - SYNTHETIC OR

NATURAL?Natural sea water is often dirty, polluted a

infected; it is always inconvenient, and therefore cos

to collect and cure; no marine organism, whether pla

fish or invertebrate, appears able to differenti

between natural and good synthetic sea water. Whemarine aquarium is established enough salt is added

the water to give a hydrometer reading, when tota

dissolved, of 1.018 to 1.021 (up to 1.023 invertebrates). Until a partial water change

undertaken (after three months to three years depend

on stocking and water management techniques) all t

is required is to make up evaporation losses wdistilled water or tap water that has been allowed

stand.

HYDROMETERSDo not attempt to save money by buying a cheap

hydrometer. A correctly made marine hydrometer will

be calibrated at a temperature of about 75F (24C)

since this is the temperature at which most aquaristskeep their coral fishes. If the water temperature is too

far from the calibration temperature an incorrect reading

will be taken. Surface tension affects the hydrometer

reading significantly: the same sea water may g

different hydrometer readings before and after a heafeed or with a dirty and a clean hydrometer.

THERMOMETERSAgain, it is wise to buy a good instrume

Thermometers are of two basic types: those which

immersed and held in place by a plastic sucker adher

7/27/2019 Marines Fishes

3/4

to the inner face of the tank, and those which adhere toan outer wall of the tank and sense the temperature

through the glass. The former type is generally much

cheaper. In any event a check on the instruments

accuracy is advisable; a known and consistent error canbe compensated for when taking readings.

HEATINGThe safest and most convenient method of heating

the water is with a combined heater and thermostat.Some of the cheaper models available are liable to

burst; this is extremely dangerous in liquid like sea

water which has a high electrical conductivity. Use anall-plastic holder to keep the heater in an upright

position with the sealer cap at or clear of the water

surface. These instruments are described as being fully

submersible but this is tempting fate unnecessarily. Thewater movement in a well-filtered and properly aerated

aquarium should ensure an adequately even distribution

of heat. The heater must, of course, have a sufficientpower output: 100 watts per 20 UK gallons (24 US

gallons) is enough for a normally heated room, but 150

watts may be needed for a poorly heated or unheatedroom.

FILTRATIONInitially only one filter is necessary for the sea aquariumand this is the high-powered under-gravel filter. This

astonishingly efficient, yet cheap and simple device is

indestructible in normal use and requires the minimumof maintenance. Powerful airlifts, operated by vibrator

air pumps, draw water down through the filter-gravel

where it is purified by micro-organisms living withinthe filter-gravel covering a perforated plastic filter plate.

Ideally this plate should cover the total base area of the

tank.

After the aquarium has run for a while and if, ow

to tank illumination inadequacies, no green algae ha

appeared, it is a good idea to fit a cheap plastic exteror internal box filter with a little filter wool and a lot

high-grade marine charcoal. This prevents the build

of organic chemicals in solution which tend to discolthe sea water to such an extent that it soon assumes

tint of pale lager-type beer if not decolourized w

marine charcoal. Organic pollutants at this level canvery damaging to delicate coral fishes. When the gre

algae appear, water discoloration is very rare.

The beginner often wonders how to tell wh

marine charcoal is totally de-activated. The chemic

physical and biological factors affecting charcoal in tsituation are complex and inter-related. For example,

aquarist rigidly adhering to the rule: 1 in (2.5 cm) off

to 4 UK gallons (5 US gallons) of tank space will obta much greater useful life from his charcoal than the o

who overcrowds. Use the colour of the water as a gui

when the water begins to take on a brownish-yellhue, slowly change half the activated charcoal. T

rapid a movement of the culture sea water through

much highly activated, marine grade charcoal can more damaging to delicate marine life than the wa

condition which it is meant to cure.

7/27/2019 Marines Fishes

4/4

Filtration media These are basically four in kind.(i) Non-calcareous gravelsSilica in its various forms,such as silver sand, beach sand, beach gravels and

shingles is non-toxic and offers a wide range of colour

and texture. Recently, coloured crushed and gradedbottle-glass has appeared on the commercial aquatic

scene and has been used in aquarium decor.(ii) Calcareous gravels Crushed coral and limestone

are often claimed to be pH buffering in effect when usedin a filtration system. Owing to the chemical

composition of aragonite it is indeed likely that this

expected effect does occur. However, it would appear,to have only a slight delaying effect on the inevitable

depletion of the alkali reserve within sea water when it

is stocked with living creatures.

(iii) Highly activated mar ine charcoalThis material isexpensive because it is much more highly activated than

cheaper freshwater charcoals. However, it is a valuablewater management aid as has been already discussedabove.

(iv) Synthetic filter wools After much work, I have

almost reached the conclusion that these are only really

useful to a marine aquarist if strongly compressed in apower-filter. Nonetheless, an argument of sorts could be

mustered for their use in external box filters using

charcoal.Recently it has become quite fashionable to lay a

layer of filter wool on top of a plastic undergravel

plate prior to covering it with filtrant gravelexperimentally ran a marine tank using this method

1967 but quickly abandoned it in the interests

hygiene. It proved impossible to clean this wool p

without totally disrupting the whole aquarium. In viof the number of competent marine aquarists whom

respect who use wool in this way, there must be stro

arguments in its favour, but so far they have evaded m

Air pumps There is currently such a variety diaphragm air pumps on the market that again one mrefer the inexperienced aquarist to his local aqua

trader. Needless to say, with such a large range he w

find some good, some bad and many indifferent pumon offer. The inevitable law that you always get exac

what you pay for was never truer than in this situati

Please do not waste your money on a multiplicity

small pumps it is untidy and wasteful even thousea aquariums do need a lot of air. Conversely, do

put all your eggs in one basket and buy just a hu

single-vibrator pump. Keep the air filter clean otherwthe rubber flap-valves controlling incoming and ogoing air will not seat properly and will impede

correct working of the pump. Where an air-bleeder

fitted to the pump use it to reduce air pressure to appliance rather than strangle off the appliance line w

a plastic clamp. If a bleed-valve is not fitted make o

by breaking the air outline line from the pump, insert

a T-piece and attaching a short length of spare air-ltube on to the T-pieces spare outlet limb. You can n

control this limb with a clamp as a bleeder-device, a

the life-span of the pumps rubber diaphragm will considerably lengthened.

LIGHTINGThis is as important in a marine aquarium as it is i

freshwater tank but for almost the reverse reason.

freshwater aquarist spends much time adjusting lighting in order to encourage the higher plants used

tank decor in freshwater aquaria. As the higher pla

flourish the algae die back. A marine aquarist, howev

has almost no higher plants to cultivate; he carefu

nurtures algae some of which look identical to those tthe freshwater aquarist is so keen to destroy.

Probably the ideal balance in a coral aquariavoiding any temperature extremes is 15-30 watts

incandescent (tungsten) light, 10 watts of colo

corrected fluorescent light and 10 watts of natural wh

fluorescent light per square foot of water surface. Tcan only be a rough guide and could be significan

modified by the proximity of the sea aquarium to

window, the number of hours per day for which elight is burnt, the depth of the water and so on.