The Heart of the System

8/9/2019 The Heart of the System

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The Heart of the System Centrifugal Pumps

Just what does it take to keep 10 million gallons of aquatic animal exhibit water

clean, clear and healthy for its inhabitants? Well, I like to refer to it as the magic

that no one knows about,! but if you went behind the scenes within the "ife #upport#ystems department at $eorgia %quarium, the &rst thing you would see would be a

lot of pumps' In fact, $eorgia %quarium has o(er )00 pumps totaling o(er *000 +'

-he ma.ority of the pumps are centrifugal, long coupled pumps and range in si/e

from to 100 +' ften described as the heart of any aquatic animal life support

system!, the pumping systems at $eorgia %quarium mo(e o(er *0 million gallons

of exhibit water combined per day and are absolutely critical in keeping the animals

ali(e at the facility' 2ut the importance here is not .ust keeping water healthy for the

animals that li(e here but also making sure that it is (isually clear for the more than

million (isitors that (isit the %quarium annually'

+ow and why are these pumps chosen? -he pump selection process for $eorgia

%quarium is critical' 3irst and foremost on the list of important criteria is ensuring

that nothing about any of the pumps selected for the %quarium can

compromise animal health' #altwater is incredibly corrosi(e and hea(y metals can

be toxic to &sh and in(ertebrates in low concentrations, so special considerations

had to be made to ensure that there were no metallic parts submerged within the

process stream' In fact, most people don4t reali/e that all of the %quarium pump

impellers, back plates and (olutes are all constructed of &berglass composite

materials' %nother (ery important

factor in the selection process is choosing

a pump with outstanding reliability for

this unique process' icking a durable and

maintenance friendly

pump is ob(iously important, howe(er the

%quarium goes one step further to ensure

reliability in its pumping system design' -his

is accomplished by specifying se(eral

smaller pumps on a gi(en process, rather

than one larger one' -his ensures adequate

redundancy in case of a pump failure' %lso, contributing to reliability are specially

designed mechanical seals to tolerate the hea(y solids and corrosion that saltwater

brings' % pump shaft grounding system is also included to ensure stray (oltage!,

which can often be generated from (ariable frequency dri(es, stays away from


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pump and motor bearings' %dd to the list a high quality marine epoxy coating an

in(erter duty totally enclosed fan cooled motor and you ha(e yourself the 5adillac!

of centrifugal pumps'

#o why so many pumps? Well, the &rst and most ob(ious answer is that $eorgia

%quarium is a (ery large aquarium facility with a great deal of water' -here are more

than )* aquatic exhibits at $eorgia %quarium and each ha(e an independent closed

loop 6not open to any natural water source7 &ltration system that ha(e an a(erage

theoretical water (olume turno(er of once per hour' -he largest exhibit at $eorgia

%quarium is the 8'9 million gallon cean :oyager, built by the +ome ;epot, habitat

which is home to whale sharks and manta rays and a plethora of aquatic species' %s

one would imagine, walking into the pump room for cean :oyager is like walking

into the engine room of the #tarship erent &ltration processes at $eorgia %quarium working

in tandem to achie(e the highly desired water quality and clarity goal' ost

common process types are primary &ltration loops including sand &lters for

particulate remo(al and speciali/ed de(ices called protein skimmers for targeting

dissol(ed organics' nce through sand and skimming, the water then splits up into

se(eral smaller side@streams' -hese include titanium plate heat

exchangers for heating and cooling water and o/one gas contactors for chemical

&ltration' Inside the heat exchanger is where the exhibit water interfaces with the

buildings +:%5 system and inside the o/one contactors is where true water

disinfection occurs' ne (ery interesting fact, the same chilled and hot water loops

used for heating and cooling airspaces within the building are also used to exchange

heat for the exhibit water' -his makes the building chillers and boilers as critical for

animal health as the exhibit water pumps themsel(es'


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Well then, who takes care of all of this equipment?

I would be remiss if I didn4t mention the truly

dedicated sta> of 1* life support operators

and two managers that work ) hours a day,

= days a week to ensure that all of the

pumps and other &ltration equipment are

functioning as they should' -his group of

operators are like the air traAc controllers for the

%quarium, using highly sophisticated computer control

equipment, including camera systems to monitor e(erything

real time' It truly takes a (illage to run an aquarium, and this team is as

important a group as you will &nd in any (illage'

Why is all of this so important? Whether you4re a maintenance worker, facility plant

manager or pumping equipment (endor, you can appreciate that the pumping

equipment that dri(es critical industry processes deser(es extra special attention' In

our case, pumps are not .ust a piece of equipment helping make a product, but

instead are an integral part or the heart! of our aquatic animal life support

systems' #o, the next time you4re at $eorgia %quarium en.oying its one of a kind

animal collection, remember that behind all of the ma.estic animals and exhibits,

the aquarium4s Beet of pumps are hard at work'!


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%eration and xygenation

Author: "aura uha

% few weeks ago, I noticed that the airstone in my 0@gallon tank was starting to&//le' Instead of perking away merrily, as it had when I4d added it to the tank somemonths before, it was emitting a feeble stream of bubbles, almost like a carbonatedsoda that4s been left too long in the sun'

Co big surprise thereD airstonesEwhether wood, ceramic, or actual stoneEare full ofpores that o(er time tend to get clogged with mineral deposits and algae' %nd whileI4(e heard of people recycling them through a multi@step process that includesboiling them in (inegar and water, scrubbing them, and forcing air back throughthem, my feeling about that isF why bother? When compared to the many otherthings that need periodic replacement in aquaria, a *0@cent airstone is hardly a bigdeal'

+owe(er, you know me 6or at least you do if you read this column regularly7, and Ilike to ask questionsD and if I can get a column out of it, all the better' -herefore, Ipresent to you the topic of the monthF airstones and other forms of added aeration'%re they reallynecessary?

Back to the Basics

-o &nd out if airstones and added aeration are really necessary, let4s start with thebasics' 3ish, like humans, need oxygen to fuel their metabolic processes, and likeus, they will die if depri(ed of it for long' +owe(er, the similarities end there,because, at the risk of stating the ob(ious, &sh li(e in a (ery di>erent en(ironmentthan we do'


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-hat4s because water molecules become increasingly agitated as the temperaturerises, and the more they bounce around, the harder it is for gases to dissol(e inthem and the easier it is for the oxygen that4s in there to get bounced out'

An !ygen Emergency

ther substances that aquarists sometimes add to water 6medications, for instance7also can cause oxygen le(els to drop' -hat4s because some such substances bondso tightly to water molecules thatEto grossly o(ersimplify an incredibly complicateddynamicEit e>ecti(ely decreases the amount of water in solution that4s a(ailable tohold the oxygen'

When this happens, &sh ha(e a number of ways to compensate' -hey can pushwater through their gills faster 6the &sh equi(alent of panting7D they also tend toho(er near the surface where the oxygen content is higher' (er the long@term, theycan increase the number of red blood cells and the concentration of hemoglobinwithin them to more eAciently transport oxygen to their tissues'

%nd in truly desperate situations, they may do what4s known as pipingEswimminghead up at the surface, opening and closing their mouths as they suck at theoxygen@rich skin of the water, something I witnessed the &rst summer I keptgold&sh'

2ack then I wasn4t experienced enough to understand stocking limits, so I put toomany gold&sh in a too@small pond' When I went outside to feed them one morning Ifound them all hanging at the surface opening and closing their mouths as if theywere gasping' % frantic call to the pond shop identi&ed the likely problem' It was(ery hot, so the water wasn4t holding much oxygen to begin withD it also waso(ercast, so the plants in the pond were probably competing with the &sh for what

was a(ailable 6and so were the nitrifying bacteria7, and the pond was stocked tocapacity so there was no margin for error' -he oxygen in the water was getting usedup faster than it could be replenished, and the &sh were desperate'

-he temporary solution was to agitate the surface of the water to get oxygen into itfaster, in much the same way that you4d stir your co>ee if you wanted to get thesugar to dissol(e more quickly' While my husband rushed out to get a submersiblepump with a fountain head while I created some temporary agitation by sprayingthe surface with water from the hose' -he results were remarkableF Within seconds,the &sh stopped gasping and began to swim normally 6although they still stayedclose to the surface7'

%fter we installed the fountain, we ne(er had another problem' +owe(er, ha(inglearned a few things since then, I now keep fewer &sh in a much bigger pondequipped with both waterfall and fountain'

So Ho" #uch !ygen $o They %eed&

%ll of this leads to an ob(ious questionF What4s the critical oxygen le(el for &sh? 2utonce again, there4s no easy answer' $old&sh, for instance, are (ery eAcient at


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getting oxygen to their tissues, so they4re able to withstand low oxygen conditionsfor longer than some other species' #o can gouramis, which e(ol(ed in the low@oxygen conditions of shallow, stagnant ponds in #outheast %sia and ha(e what isknown as a labyrinth organ' -his is a sort of primiti(e lung that allows them tobreathe surface air when they can4t get enough from the water'

$enerally speaking, howe(er, large &sh use more oxygen per hour than smaller &sh,and faster@swimming &sh use more oxygen than slower swimmers, while fry oftenneed more oxygen than adult &sh' % &sh4s consumption of oxygen also increasesafter feedingEsome studies ha(e found it to be by as much as *0 percentEbecauseof the energy demands of digestion and growth'

+owe(er, the picture is further complicated by the fact that &sh are cold blooded, sothe speed of their metabolism corresponds to the temperature of the water they4reswimming around in' -he problem is that the warmer the water gets, the moreacti(e the &sh become, and the more oxygen they need to fuel their increasedacti(ity 6their demand can double or triple with e(ery 10@degree increase intemperature7, but warm water also holds less oxygen'

Aeration $e'ices: Are They %ecessary&

-here are a number of ways to help counter this, and that4s where aeration de(icescome in' -here are two basic typesF -hose that infuse oxygen directly into the water6such as airstones and decorati(e bubble walls7 andEe(en more e>ecti(eEthosethat expand the surface area of the water to gi(e the oxygen more entry points'

-hat4s what I was doing when I sprayed my pond with the hose, for instance,because each droplet of water picked up a lot of oxygen as it cascaded through theairD that4s also part of the point of waterfalls and fountains' %nd in aquariums,certain types of &lters help aerate the water as well' -hese include hang@on@back

&lters and trickle &lters'

#ome &sh farms in(ol(ed in high@intensity aquaculture sometimes use such meansto hyperoxygenate the water, which allows them to increase stocking le(els withoutincreasing the amount of water in their systems' +owe(er, there are someindications that this can stress &shD in one paper reported at a World %quaculture#ociety meeting in 008, #wedish researchers found higher le(els of the stresshormone cortisol in %tlantic salmon that had been raised in hyperoxygenated water'

-oo much oxygen in water can lead to the potentially lethal gas bubble disease, inwhich gas comes out of solution inside the &sh, creating bubbles in its skin andaround its eyes' 6


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that4s what you4re worried about, there are more e>ecti(e ways to do itEwith atrickle &lter, for instance'

n the other hand, can airstones and other bubblers ser(e a useful purpose? Mes,within limits' -hey do add some oxygen to the water, and the bubbles they createhelp to keep water mo(ing within the tankD by strategically locating it in areas in

which water circulation might be lessEnear the bottom, for instanceEyou4ll help tokeep suspended particles circulating so that they can be sucked out of the water bythe &lter'

#o while I4m not going to bolt out to the pet shop to replace mine the way I would if,say, my &lter quit working, I4ll probably pick one up e(entually' 2ecause when itcomes to aeration, e(ery little bit helps'

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The Heart of the System