FISHERIES RESEARCH BOARD OF CANADA
Tech no log ic a I Research Laboratory
•
Halifax, Nova Scotia
. D. R. IDLER,
New Series No. 13
Dfrector
CIRCULAR
March 30, 1963
A Continuous Flow, Seawater Aquarium Suitable For
Experimental Work With Live Marine Animals
By
JAMES E. STEWART and H.E. POWER
ABSTRACT
The construction of on aquarium with a continuous flow sea water supply suitable
for holding and experimenting with fish and shellfish is described and discussed in
detail. The system consists of 42 animal holding tonks, each tonk having a capacity
of 84 Imperial gallons. Sea water is pumped continuously from Halifax harbour, through
filters, Into the holding tanks and the displaced water is drained bock. to the harbour
through on overflow system.
The experimental work in this laboratory requires
the liolding of large numbers of live fish and shellfish under conditions closely approximating the
natural environment. The lack of published information on the necessary physical equipment and the
problems encountered in its construction lead to
the belief that other investigators interested in
working with live marine animals would profit from
a description of the holding facilities and sea water
supply system recently installed at this laboratory.
Natural sea water was chosen for use because
of its availability and because artificial sea water
is a costly and not entirely adequate substitute.
The use of natural sea water also dispensed with
the need for a closed system and the accompanying
filters required to remove the animals' waste
.products, surplus food particles, and other materials.
A closed system though expensive and elaborate
is mandatory when absolute control of conditions
is required in the experimental work. This laboratory is fortunate in having both an open and a
closed system. The open type only will be described
here.
I.
In Canada the Department of Public Works and the
National Harbours Board have Jurhdictlon over navia:able
waters and harbou.. re"pectlvely.
Permlulon muet be
.oua: ht Crom and a:ranted by theae aa:encie. before any
"work." can be placed In waters under their control.
Sea water is piped from a point in Halifax
harbour 600 ft from shore and 50 ft below the surface
of the water at low tide -(1)~ The pipeline terminates
in the aquarium building in two priming and screening
boxes, and a centrifugal pump, alternating with a
standby, is run continuously to pumI5 the sea water
from one of these boxes. Water from the pump is
filtered first through sand and gravel, coarse
filtration, passed through a small pore size filter,
fine filtration or polishing, then led into an overhead piping system to be distributed to the animal
holding tank.s in the aquarium.
The aquarium consists of a structural steel
framework supporting two levels of insulated
fibreglass tanks, each level containing 21 tanks.
Sea water is fed from the overhead piping through
a valve installed on the lead to each tank to control
the inflow. Standpipes set into the corner of each
tank provide drainage and water level control.
All tanks drain into a common pipe which leads to
the city sewage system. The aquarium is darkened
and the upper storey of tanks is exposed to automatically controlled illumination (Stewart, 1963).
Ferrous metals in general are not toxic to
to marine animals but many other metals are; consequently, every effort has been made to use nonmetallic materials. In the few places where it was
found necessary to use metal, cast iron or Type
316 stainless steel was used.
Fisheries Research Board of Canada
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Water Intalce System
A schematic diagram, Fig. 1, shows the general
layout and major features of the running sea water
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Fig. 1 - Schematic alagram showing the genfll'al layout
ana major leatures 01 the aqUGrlum ana sea
wat.r .upply system.
(1) Concrete water
Intalee bracleet. ana anchors, (2) 3 In• .po/yethylene pipelines. One pipeline I. In place
ana the other will be lala soon. (3) Concrete
linea pit, (4) Priming ana screening boxe.,
(5) Pumps, (6) 1\.2 In. rubber pip., (7) Bypass
or water outlet valve, (8) Sana ana gravel
IIIter., (9) Water outlet to clralns tl!'d positIon
of transparent plastIc tube, (10) Sparle/er
IIIter, (11) Bypass or aaalt/onal water outlet,
(12) 1 In. plastic pIpe, (13) ~ In. plastic pip.,
(14) Ra/sea walle way, (15) \.2 In. plastic pipe,
(16) Upper storey 01 animal holalng tonics.
system. The seaward terminus of the water intake
is a screen-topped, plastic-lined, salt water resistant, concrete bracket or anchor illustrated in Fig. 2
and Fig •. 3. The end of the pipe is cast permanently
in the concrete. The water pipe which extends
from the anchor to the building was custom-made
in one piece and is a 650 ft length of 3 in. inside
diameter, black, Class B (75 lb pressure test),
polyethylene pipe, the largest diameter plastic
pipe obtainable in one continuous length. Heavy
walled, polyethylene pipe can be wound on a spool
during fabrication and straightens out with remark-
Fig. 2 - Re/nforcea concrete waf• ., Intalee bracle.t anJ
anchor. (7) Steel plate top with \.2 In• .perlorations, (2) St_I,rod screen; 2 In. .w lae squares,
(3) Steel plate bottom with \.2 In. perloratlon••
Numbers (1), (2) ana (3) represent the screen
which I. neoprene coverea.
(4) Flange.
coup/eel together by nylon nuts ana bolt.,
(5) ABS K150, 4 In. pipe, (6) Square, 18 In.
wlae, concrete column, (7) Position 01 one
01 three eyebolt., (8) Flanges coupleel wlt~
bra.. nuts ana bolt., (9) 4 In. polyethylene
bushing, (10) 650 It length 01 3 In. polyethylene
pIpe, (11) Po/yethylen. reInforcing blocles
welaea to 3 In•. pi,., (12) Concrete base.
able ease during laying operations as long as the
material's temperature is 40 0 F or higher. Annular
30 Ib weights made of concrete cast around 8 in.
lengths of 4 ' in. class A, black polyethylene pipe,
through which the 3 in. pipe was threaded, hold the
pipeline in position on the harbour bottom. All
work was completed on the surface since the pipe
floated until the air was expelled, even after the
addition of the weights.
Laying operations took approximately 5 hr. A
floating crane set its 'anchors at the predetermined
location of the seaward terminus of the pipeline
where the depth of water is approximately 60 ft at
low tide. The crane came alongside the whatf and
took the concrete anchor !%hoard leaving the spool
of pipe on the wharf (Fig. 4), then kedged slowly
backwards to the predetermined site thereby stringing
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the pipe on the surface of the water. The shoreward end of the pipe was taken over to the aquarium
building, the weights slid on, spaced at 12 ft
intervals and tied in position from a small boat
(Fig. 5), the pipe fastened securely ashore, the
screen attached to the concrete bracket, the slack
taken out of the length of pipe and the anchor
lowered at the correct location. The pipe sank
gradually as the air was replaced by water. Underwater work consisted of an inspection by a diver
equipped with SCUBA .
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. Fig. 3 -
Concrete water Intake bracket shown with
neoprene coverecl screen In place.
Fig. 5 - Spacing ana tying the weights In position.
The extreme length of the underwater section
of the pipe, 600 ft, was made necessary by inshore
contamination and great depth of mud; the heiqht
oft the bracket ensures that the end of the pipe is
kept well out of the lesser depth of mud found at
that distance from the shore. The pipe is buried
between the shoreline and the building, a distance
of 50 ft, and enters the building below floor level,
thus reducing the lift required of the pumps. An
8 by 10 ft concrete lined pif, 4 ft deep, was sunk
in the end of the building to accommodate a pair of
priming and screening boxes, the pumps and pipeline terminus.
Removable aluminum paneling over
the pit becomes part of the floor of the room above,
thus - conserving space. A square, 1 cu ft lined
cavity in the floor of the. pit provides drainage for
spilled water and an installation position for a
continuously operating, electrical sump pump, thus
keeping the pit relatively dry at all times. A
second pipeline will be laid soon to increase the
water supply and provide an alternative supply in
the event of destruction, damage or fouling of the
first pipeline.
Fig. 4 -
Water Intake bracket being taken on boarJ
the Iloating crane; the spool 01 3 In. pipe
remaining on the whorl, lower lelt.
Fouling of the pipeline by materials large
enough to block t1~e water intake is prevented by
the screen attached to the top of the concrete
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anchor. Materials which collect or cling to this
screen may be removed by reversing the dirE!ction
of the water flow or, in exceptionally difficult
cases, by a diver. Although no reduction of flow
through the pipe has been noted in the 8 months of
continuous operation, and no material has been
picked up in the priming and screening boxes,
fouling by growth in the pipeline is a real possibility.
The ability to reverse the flow of water and pump
fresh water, caustic, or toxic solutions through the
pipeline is a distinct advantage and should allow a
thorough cleansing of the pipe.
Maintenance
01 Water
T emperatur.
When the incoming water is expected to maintain temperatures approaching those existing in
the natural environment, the following points should
be considered in deciding pumping rates and capacities. The animal holding tanks, 3 ft wide, 3 ft
long, and 1~ ft deep, contain approximately 60
Imperial gallons when filled to a depth of 14 in.
. The amount of incoming water required to keep the
60 gal within 10 C of the incoming water temperature,
when the open topped tanks are covered on all
external surfaces with 1 in. thick polystyrene insulating material and a 200 C differential exists
between the room and incoming water temperature,
has been calculated to be 1 Imperial gallon per
.minute (IGPM). The relationship is linear; thus a
lOoC differential between water and room temperature
would require a flow of 0.5 IGPM to maintain the
tank temperature within these limits. HalVing the
water volume held in the tanks or increasing the
limits ' to. maintenance of the tank temperature
within 2°C of the incoming water temperature
halves the required flows listed above.' If the
flow is reduced, then of course the oxygen supply
is reduced, and would probably have to be supplemented depending upon the animal load. Water
temperatures are monitored continuously with ci
recording thermometer.
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ever, the consequence of trying to exceed these
volumes is cavitation and a break in the column of
water resulting in a loss of water flow and damage '
to the pumps. Installation of an intake pipe, the
size of which allows , considerably greater flow
than the 'pump can draw, would prevent' loss of
water by cavitation. This would also permit some
expansion of the facilities.
,Two centrifugal, cast iron pumps with 7 in.
impellers, belt driven at 3500 r.p.m. by 5 hp electric
motors have been used. Priming has been accomplished by the instaliatiol), of the pair of boxes
mentioned above and shown in Fig. ,6, whiGh in
addition to their priming function also screen out
materials likely to cause pump malfunction. The
priming boxes were w:elded from ~ in. steel plate,
reinforced at the seams with steel angle strips,
ribbed on the outside for extra strength, and lined
with 1/16 in. ,neoprene sheeting to prevent corrosion.
The circular screening baskets were made from
sheets of 0.0625 in. steel with 3/16 in. perforations
and were covered with 1neoprene paint.
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Pump S.I.ction
Centrifugal pumps are capable of a maximum
suction lift of 15 ft. This system with a maximum
actual lift of 7 ft at extreme low tide, plus pipe
friction losses, is limited to a maximum volume of
approximately 75 IGPM through this length of 3 in.
pipe under the least favourable conditions. A
reciprocating pump is capable of a 22 ft maximum
suction lift and under the same conditions could
draw a maximum volume of approximately 104 IGPM.
These are conservative estimates based on poor
conditions.
Actually these conditions are mitigated by the fact that extremely low tides occur
infrequently and even ordinary low tide levels
exist for only brief periods ~wice each day. How-
Fig. 15 - Priming and screening box. (1) Vacum gauge,
(2) ~ In. diaphragm valves; water Inlet and
air release, (3) Flanges coupled with brass
nuts and bolts, (4) Rubb., gaslcet, (5) 3 In• .
water Inlet, (6) St_I tonic covered Int.,nally
wl,h J/J6 In., neoprene ard painted exte,..
nally with neoprene paint, (7) Removable,
neoprene painted, circular screening ba.k.t;
3/J6 In. ,perforations, (8) StHl angle frames,
(9) 3 In. waf., outl.t.
One pump runs continuously maintaining a flow
rate of approximately 50 IGPM; the other :is kept as
a standby un~t. The high rate of corrosion experienced with tlie high speed, cast iron pumps makes
Fisheries Research Board of Canada
the added expense of stainless steel, plastic, 'or
reciprocating pumps less forbidding and probably
a wiser investment. It is well to obtain pumps
whose rated capacity is considerably above the
immediate requirements to_provide for 'the inevitable
expansion of holding facilities, and allow lowe;
operating 'speeds thereby reducing wear and extending
the, life of the pumps. Slow speed, double acting,
electrically driven piston pumps with corrosion
resistant fittings would probably be the most suitable and are recommended by the authors for this
pumping job.
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3 to 4 ' day intervals.
The size of the individual
filter unit is qenerally limited by the amount of
water available for washing a single unit. Fresh
water of course can be used to supplement the
sea water ;for washinq purposes.
The authors intend to polish the water by
passing the effluent from the sand and gravel
filters through a Sparkler Tube Filter (2,3), ~hicli
Piping and Valves
Wire or fabric-insertion rubber pipe with clamp
type connections was used for the main distribution
lines in the building; it is more flexible than
plastic pipe so that tighter connections can be
made, the pipe more easily strung, and condensation
on the pipe surface is less than on plastic pipe.
'J'his pipe was kept large in relation to flow in an
effort to keep high pressures ,and friction losses
at a minimum. Condensation on the pipes, while
not a serious problem, can be overcome completely
by wrapping the pipes with insulating material.
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Water is pumped from the priming boxes through
updraft ' sand and gravel filters (Fiq. 7) which
remove the larqe quantities of suspended' material
found in these waters. Filters of this desiqn work
effiCiently at a service flow rate equal to or less
than 3 IGPM per sq ft of surface area. Increasinq
the rate of flow in the service line to 9 IGPM per
sq ft of surface area for 5 to 10 min washes the
filter satisfactorily by liftinq and tumblinq the
SCftld in the hiqher velocity water. The flow -rate
of the water must be sufficient to lift and tumble the
sand durinq the washinq operation but insufficient
to carry the sand particles out of the filter. , A
transparent plastic tube in the drain line permits
visual observation of the proqress of the cleansinq
action. After the wash water appears to be clean
t he flow 1s reduced to service rates and the water
passinq through the filter is run out the drain for
10 min. Washing and resettling of the sand beds
is now complete and the filter is returned to service.
The frequency of washinq, which depends upon the
amount of suspended solids in the water, is easily
determined during the early stages of operation.
At the Halifax laboratory t~e filters are washed at
7" LAYER COARSE
QUARTZ SAND
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Polyvinyl chloride ball valves control water
flow in all the main lines i.e., distributing water
.for service requirements, bypassing the filter
system, running water for additional needs or
diverting water intI:? the sewage system.
Filtration
8" LAYER O.3-lmm
QUARTZ SAND
FIg. 7 - Sand and Gravel fll,.,.. ', (1) lY.l In. polyvInyl chlorIde (PVC) bait valve water outlef,
(2) Pre.sure gauge, (3) Flange. coupled wlfh
bra.. nut. and bolf., (4) Rubber gasleet, (5)
l~ In. PVC bait val.,. water outl.f, (6) 2 In.
tltlelr Insulation with waterpraol facing, (7)
Strongly reinforced flbreglass _II, (8) Remo""
able, 5/16 In. , fhlcle, flbrefJlas. .helf wlfh
~ In. per/oratlon., (9) F/breglas. .upport for
outer edge of removable .helf, (lO) l~ In,
PVC ball valve water Inlef, (ll) 5 In. .length.
of 3 In. diameter, CIa.. S, polyethylene pipe
wltlt 3/8 In. perforation., (12) Strongly reInforced, fI&reglass bottom, (13) l~ ' In. PVC
ball valve exldlt/onal water Inl.t or draIn.
has 8 perforated tubes lined with high wet strength
paper, providing approximately 20 sq ft of filtration
surface. The rated capacity of this type of filter
2.
Spukler IDtemaUODti Ltd., TOl'Ollto, Ontario.
3.
.. ...UOD of a manufacturera' product a ia made for the
purpoae of proyidlna: a more eXlict deacrlptlOD _d Ie not
to be taken lIa an eadoraement of thee e producta by the
Piaheriea Reaearch Board of C ....d ••
. Fisheries Research Board of Canada
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is 3 IGPM per sq ft of surface area. All metal
parts of this filter are stainless steel; the tank is
epoxy. lined and can be obtained with a neoprene
lining if this is preferred. Water can be pohshed
by means of diatomaceous earth, cellulose cartridges, or high wet strength paper filters, irradiated
by ultraviolet light or otherwise treated for special
purposes. Without prior filtering through sand and
gravel these polishing procedures fail because of
the very rapid clogging of the filter media. At
present some of the water from the sand and gravel
filters is being polished by small, Cuno Aquapure
Water Filter Cartridg·e s (3,4)
the top of the upper storey or .row of tanks and the(""'\
ceiling to permit the installation of a third storeyV
of tanks. The bottom of the lower row of tanks
is 18 in. Irom the floor permitting the installation
of drains and a 30 in. gap has been left between
the top of the lower row and the bottom of the
upper row for drains, service fixtures, and working
space. If controlled illumination is a requirement,
a slightly larger gap should be left between the
rows of tanks to accommodate the lights and
reflectors at the desired distance from the water
surface.
.Air Supply
Distribution and Drainage 01 Water
Water leaving the filters is fed via the rubber
main lines into a plastic overhead manifold made
from 1 in. pipe reducing through a ~ in. section
to ~ in. line with leads into the holding tanks.
Threaded fittings were used in the manifold. Flow
into each tank is regulated by a ~ in., rubber
lined, diaphragm valve with polyethylene body and
a cast iron bonnet. Water levels in the tanks are
maintained by means of a 1 in. plastic standpipe
set into a rubber stopper which in turn is forced
into the 1 ~ in. drain in the corner of each tank.
A common set of plastic drains, increasing from
an initial size of 1~ in. to 2 in~ pipe, connect
below the tanks to lead the overflow into the
the sewage system.
Fibreglass Tanks and Supports
The existing facilities provide for 42 ·tanks,
made of heavy duty fibreglass and finished inside
with a green gel coat, supported on painted, steel
frame stands. Part of one row of tanks is shown
in Fig. 8. Sufficient room still remains between
Air supply lines strung overhead inject air
into the water in each tank through an "air stone".
The air supply can be continuous or started automatically through operation of a solenoid valve
attached to the water line. Ordinarily, air is not
required since the water contains considerable
amounts of oxygen, but, if the water pumps should
fail the air supply assures that the animals will
not die until the temperature rises above their
tolerance limits. T.he polystyrene insulation on
the tanks prevents a rapid rise in temperature.
An air supply is necessary when the .ani!llals'
requirements exceed the amounts of oxygen naturally dissolved in the water such as occurs in
temporary overloading of the tank.
Pressures'
Pressure gauges have been installed before
and after the filters to indicate increasing pressure
drops and thus the arrival of the time for washing ·
the filter. Pressure operated alarms give warning
of low or high pressures due to cessation of the
water £low or blockages in the lines. The system
has been designed for normal operating pressures
of up to 65 p.s.i. with sufficient strength to withstand temporary pressures conSiderably greater
than this figure. Normal operating pressures lie
between 35 and 60 p.s.i.
Space Requirements and Floor Loading
Fig. 8 - Part of one level of animal holding tanlc.
4.
Peacock Broe. Ltd., Montreal, Quebec.
The floor space occupied by the 2 · storeys of
tanks measures 15 by 30 ft, the filters and ancillary equipment require an additional 5 by 15 ft
area, or a total of 525 sq ft, excluding the pumping
station installed in the concrete pit. Floor loading
is not a serious problem since the weight has
been distributed over the entire floor by attaching
steel footings as base plates .to the tank stands.
The building's floor is reinforced, 3000 p.s.i.
concrete, poured on a tamped gravel base, and
was designed for a loading of 100 Ib per sq ft.
Fisheries Research Board of Canada
R...ark"s
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includes salmon, cod, lobsters and oysters; Part
of the system is supplied with dechlorinated
fresh water and is beinq used to hold and experiment with younq salmon, trout and salmon eqqs.
The facilities described above are extremely
versatile and can be used for keepinq a wide
variety of marine animals. .The size of the animal
holdinq tanks is convenient for "much of the experimental work done in this laboratory and the larqe
number which can be fitted into a limited space
permits more diverse experimentation than would
be po4sible with the equivalent total volume of
water distributed in a few larqe tanks. Very little
work is needed to convert part or all of the system
to a "fresh water supply and the chlorine, which
is added to "most city water supplies, can "be
removed by passinq the water throuqh an activated
charcoal filter.
When controlled temperatures
are required, the flow to the tank can be reduced,
air injected into the water, and the water warmed
"by qlass enclosed immersion heaters or heat
exchanqers.
If the nature of the experimental
work permits it, lonq term temperature control can
be obtained more economically by isolatinq one
or more tanks and operatinq them with water recirculated from a 'controlled temperature reser'loir
or heat exchanqer with toxic wastes removed by a
separate filter i.e., by operation of a closed type
of aquarium. At present the list of animals held
in runninq sea water takea from Halifax harbour
Aclcnow/edgmen,s
The authors express their thanks to Dr. D.R.
Idler, Laboratory Director, for siqnificanl contributions to a solution of the filtration problems.
The authors also thank, for technical assistance,
work, and advice, Mr. R.C. Palmer, Supervisor,
Technical Services, Mr. R. Greeninq, Mr. J.W.
Gates, Mr. D.J. Casavechia. Mr. R.C. Edmonds
~d Mr. D.E. Turner, all of this laboratory. The
cooperation and help of the Naval Research Establishment, Defence Research Board, Dartmouth,
Nova Scotia, Mr. "L. Baker, Maritime Area Director,
Canada Department of· Fisheries, and the National
Harbours Board is qratefully acmowledqed. Special
thanks are due Mr. J. Cuddy, Maintenance Super-visor, Naval Research Establishment, Dartmouth,
Nova Scotia for his extremely useful advice and
his supervision of the pipeline installation. In
addition, the authors express their appreciation
for the photoqraphic work done by Dr. ~.R. Dinqle
of this laboratory.
Reference.
Stewart, J.E. 1963.
An arranqement for automatically and reproducibly controllinq and
varyinq illumination in bioloqical experiments.
J. Fish. Res. Bd. Canada. (In press).
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Fisheries Research Board of Canada
Printed in Canada by the Queen's Printer
for exclusive disuiburion by the Fisheries
Research Board of Canada, Ottawa, 1963.,