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"Plumbing a Water Return
Manifold - goodbye powerheads!"
|
Olde Tech:
Better to employ inside/internal pump mechanisms...
less leak potential, better flow control, less expensive to
operate. RMF
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by Anthony Calfo
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Wavebox and closed loop question
2/7/11
Hello Crew,
<Barry>
I've got an 8 ft long 240g tank with 2 corner overflows and a 1.5
in drain built into the back wall of tank. I eventually want SPS in it.
I just ordered a Tunze Wavebox and would like to know if I should
attach a closed loop system to the back drain and maybe an OM 4 way
(since the plumbing with 4 outlets entering
surface of tank is already there) or should I just go with some
internal pumps.
<Myself, the last choice assuredly>
Would the closed loop interfere with the Wavebox?
<Not really, but this tech. is really "old school"... not
efficient, plagued w/ real and potential troubles. I would NOT use a
closed loop system on any marine set up nowayears>
I've already got a Reeflo Snapper as my return pump from the 80g
sump below. Thanks.
Barry
<See here: http://wetwebmedia.com/marsetupindex2.htm
the third tray: Circulation.
Bob Fenner>
Re Wavebox And Closed Loop Question, JamesG
input 2/8/11
"<Not really, but this tech. is really "old
school"... not efficient, plagued w/ real and potential troubles.
I would NOT use a closed loop system on any marine set up
nowayears>"
Bob, I totally agree with you 100%.
James
<<Yes... more money to move less water, not near as much
flexibility in directing flow/currents, much more chances for leaks...
Where's the upside? BobF>>
Re Wavebox And Closed Loop Question
2/8/11
There is no upside, all those bulkhead fittings scare the hell out of
me, definitely not worth the expense, trouble, and worry.
James
<Our thoughts are confluent. B>
caption: Depicted here, the rudimentary skeleton of a simple
water return manifold. The primary purpose is to offer greater control
over the finesse of water flow in the display. Its teed outlets get
fitted with fine adjustable aspects - see text below. With this
application placed at or slightly above the water surface, one can
avoid unsightly powerheads in the display while also reducing their
expense and redundancy, beyond issues of poor flow control and excess
heat imparted by them. Illustration by Kevin Carroll
One of the most frustrating aspects of aquarium-keeping with marines
is creating optimal water movement in the display. Success is often
hampered by other common flaws in planning and plumbing, like
inadequate drainage (hole numbers and sizes) and the very rockscape of
the display, which too often is crippled without a 4" minimum
distance from any wall. Water flow issues can literally make or break a
tank. Some popular fishes express neurotic behaviors like
"pacing" in slow flow environments: swimming back and forth
against the glass relentlessly as if pursuing their own reflection.
Some tangs, for example, will cease this behavior with increased water
flow. Sessile reef invertebrates depend on accurately applied water
flow to bring food to them and to carry waste away. Their very lives
will be threatened furthermore in poor flow environments over time and
in ways that some aquarists can easily overlook, like encroachment by
algae and poor gas exchange from the increased thickness of the
microlayer than runs anoxic near their body. The dynamic snowballs as
waste accumulates, mucus accumulates, bacteria proliferate and
ultimately become pathogenic; it's the very thing that kills so
many corals in shipping. There is also the simple matter that an
increase of water flow in traditionally under-filtered aquariums often
translates into prompt and improved rates of growth in captive animals.
And finally, on more elemental level, effective water flow is necessary
in the aquarium to prevent the accumulation of detritus, and worse -
lingering matter that dissolves and concentrates over time (ie- 20%
water changes still leave 80% of the undesirable contaminants generated
behind to accumulate). Good water flow will keep solids in suspension,
which increases feeding opportunities by fishes and invertebrates, and
improves filter/skimmer opportunities to export such matter in a
well-designed system.
Powerheads are certainly one of the most popular ways aquarists
create water flow in the aquarium, yet the technology has its flaws and
may not be appropriate for advanced marine systems. They are generally
constructed for short to medium-term life, with many being so
inexpensively constructed and offered that they are regarded as
"disposable". Some will last more than five years (uncommon),
but even they are generally "tired" and only able to provide
reduced flow. Most have a useful lifespan of less than 5 years. While
we are on the topic of failure and modest construct - what about shock
hazards? Good heavens, it is amazing and frightfully common how many
people have gotten a shock from a faulty powerhead! Yet it is not
actually surprising. Take a look and you will find that most have
non-grounded and even non-polarized plug ends that are simply
epoxy-sealed into the motor housing. That seal has a limited
life… and so will you if you neglect to employ a proper GFI
(ground fault interrupter) for your wet aquarium station. What else can
we fault powerheads for? Imparted heat - a silent problem inherent with
any submersible pump and amplified here by the number of units sunk in
the tank to achieve the same water flow as a single cool-running
external water pump. For displays with other heat issues (like enclosed
and poorly vented lighting systems), powerheads used for primary water
circulation contribute more than a few degrees to the water
temperature, which can be a serious problem. Of lesser concern but
still worthy of mention is the risk that their unguarded intakes pose
to aquatic life. Many aquarists have lost animals unnecessarily this
way - particularly benthic motile invertebrates, slow/weak fishes, and
anemones & toxic sea cucumbers that wait until you go on vacation
to drift. Guarding the intakes instead increases the need for upkeep
unduly: a small guard clogs quickly, and a large guard runs the risk of
becoming an unwelcome nitrifying surface. In systems with high flow
needs overall, it may take 4 or 6 or more powerheads to produce the
same flow as a single external pump. And at last, power heads are
staggeringly unattractive and distracting in the display proper to many
observers. Their only saving grace is that they are cheap and
affordable, which allows newer aquarists in particular to "buy
into" the hobby - a very important and worthwhile distinction.
This article, however, is not likely to be directed at new
aquarists. While the application of a water return manifold is simple
enough to construct (and mere dollars worth of plastic for most),
concepts of sumps and hard plumbing with valves and adjustable fittings
are unfamiliar if not daunting to the truly novice participant. Old,
salty dogfish however (experienced aquarists, that is…), have
earned honorary degrees in chemistry, carpentry, plumbing and
electrical engineering to become reef aquarists. Hopefully, some
well-prepared and researching new folks will read this and be spared
the gauntlet of powerhead pits just the same. Advanced aquarists are
charged to pass the word along in kind if they agree.
Harnessing an external water pump, a manifold of PVC is to be
plumbed with a single feed line. [Please refer to the 3-D manifold
illustration atop this article for a visual cue to the continued
description of its general employ - sump version shown] This feed pipe
runs up to the manifold and taps in by a tee. Branching off below this
closed loop for any other applications is not recommended; we need a
dedicated supply of water here. Obey the manufacturers recommendations
for line size. Home aquariums of a couple hundred gallons or less will
likely use 1" or ?" pipe. Larger pumps and systems will use
accordingly larger plumbing for this purpose.
The manifold ring/loop of PVC is closed in a complete circuit to
help balance the water dispensed from each outlet. Control nozzles will
afford the final tuning needed in this regard. Most folks build their
manifold the size of the inside perimeter of the display tank. For
aquariums with a commercial plastic trim, small holes can be drilled in
the recessed lip for plastic ties (cable/zip) to be fished through for
securing the suspended manifold. Bare glass aquariums (no trim) can
have fasteners (plastic hooks, cable ties, etc) embedded into a dab of
silicone near the edge and put to use once the caulk is cured. Acrylic
aquariums are very accommodating and can easily be drilled or glued
with whatever fasteners work best and are most discreet. Placement of
the manifold at or slightly below the water surface (the nozzles at
least) reduces or eliminates any issues with salt creep or salt
spray.
Tapped into the manifold ring we need multiple tees, angled slightly
downward as a good-sense precaution in case the nozzles leak or become
"liberated". The placement of these tees is not of much
critical concern as long as you have enough in total to work with; the
ability to manipulate water flow through any of them is very flexible
and efficient. I'll suggest 4 to 6 teed outlets per 100 gallons of
tank volume, spaced evenly apart, as a starting point. Frankly, you
should have no fear constructing a manifold for how inexpensive the
framework is to build. In the worst-case scenario, a scrapped structure
is a lesson of $20 or less in plumbing, which is a pale and worthwhile
investment in light of the value of the display tank.
caption: "Profile of a small reef (36"
long - 50 gallon) with a partial manifold (loop is not closed and
nozzles not installed yet). Notice the discreet feed through a back
wall bulkhead (upper left side of pic), covered by a black shield, fed
under the central brace and secured to the obscuring upper front trim
of the aquarium with plastic cable ties. Note: the PVC fittings
siliconed to vertical glass panes are deliberate pockets for corals to
encrust upon behind the rockscape for dimension as the tank
matures".
Next we must decide on the type of nozzle for inside of the manifold
tees. They should be movable/swivel… and ideally be able to
restrict or regulate water flow. It's at this point where the
project can get as expensive and complicated, or not, as you like. To
keep expenses very low, PVC elbows (usually 45-degree) and nipples
(short lengths of pipe) are the best way to go. Fittings for small
plastic pipe generally cost well under $1 each, or several for a dollar
in bulk. A single stock length of straight pipe is like-wise but a few
dollars. Short nipples of pipe (1-3") can be used to connect
unglued 45-degree elbows to each teed outlet. The tapered slip sockets
of the elbows will afford a snug and water tight seat without
committing to a glued position. They can then be swiveled to finesse
the dynamic of water flow in the aquarium as corals grow or wane, or
when the seascape changes for any other reason. A slight restriction of
water flow can be achieved by heating another short stem of pipe and
crimping it to produce a restricted flare-tip that will increase the
velocity of effluent water. This modified nipple is to be placed, of
course, into an effluent tee. Some discretion is required here,
however, as the resistance from a single crimped outlet will likely
translate into water taking an easier path of resistance - namely,
another open outlet(s). To compensate for this, all outlets need to
have similar modifications/restrictions, or valves will need to be
installed for each outlet. Valves are not emphasized here as they add
considerably to expense, are generally not needed, and complicate a
delightfully simple application to excess (creating a "juggling
act" with one adjustment affecting all). Another concern is that
if the manifold does not have enough outlets, there will be undue
pressure placed on the pump (generally harmless for magnetic drives,
but perhaps harmful to direct drives). On the opposite end of the
spectrum, if too many outlets are installed (more is generally
better/safer for future pump upgrades), they can easily be capped
(glued or unglued) with a PVC cap and short stem/nipple. Truth be told,
most tanks will be served very well with unrestricted outlets that
merely have swiveling 45-degree elbows.
Nonetheless, some aquarists will have more discriminating
preferences… and some corals certainly have more demanding needs
regarding water flow. This is especially true in display with large or
fast growing corals that have a monthly need for modifications in the
delivery of water flow. While the above-mentioned swiveling elbows have
a very wide range of motion and coverage, there is an even better
option: Flexible Ball-Socket Joint Tubing (wide industrial
usage, but found in the aquarium trade at comprehensive LFS shops and
online at MarineDepot.com, and elsewhere). This interlocking pipe is
much more expensive per foot than standard DIY PVC parts, but very
little of it is actually needed. The product line is complete with
numerous adapters for connection to PVC plumbing, as well as add-on
fittings to manipulate the ou-going water. A short length (perhaps just
3-6") is all that is needed on the end of each teed outlet on the
manifold to superbly finesse water flow in the aquarium as needed.
Clearly, effluent direction on the manifold can be tweaked and tuned in
ways that are impossible with rigid and planar powerheads.
Ultimately, the goal with any interpretation of outlets/nozzles that
you may choose to employ is to get the outflow paths to converge in the
water column to produce random turbulent circulation that is nearly as
ideal as surge motion but far less complicated to produce. Dump and
surge buckets/devices produce excellent water movement but are
generally noisy and inconvenient to install and operate. They are often
finicky, and produce problematic snapping and micro-bubbles, and
excessive salt creep that is unduly warranted for a home aquarium. They
are also cumbersome in size and aesthetically detractive for most
living spaces. Such devices are better suited for very large systems,
like public displays. Wave-timers with powerheads are likewise inferior
to dedicated pumps producing random turbulent flow as their staccato
operation increases wear on pumps in use while robbing the system of
potential water flow during "off" cycles. Truly, the closed
loop manifold described herein produces some of the most efficient
water movement in the aquarium while insuring a good value of use (pump
life and "bang for your buck" regarding watts used to produce
X measure of water movement).
Aquarists for some time have also used external water pumps plumbed
directly in and out of an aquarium (no open sump necessary) in a
fashion that is called "closed loop". It lacks a
manifold… and actually, lacks any notable means of finesse -
it's simply an external water pump sucking water out of a tank and
blasting it right back in. It is crude, but serves a very important
role in aquariums with high flow demands that exceed the desired (or
able) abilities of a sump path return often hampered by inadequate
overflows. [Please don't get me started on a discussion of the
ill-conceived and so-called "reef-ready" aquariums being sold
commercially. I still cannot fathom what kind of reef they envisioned
with their meager holes/flow rates. Their flow-through capacity is
crippling… hello algae!] A closed loop pump on the display, with
or without a sump installation, can be harnessed to power a manifold as
described above. Since the intake is tapped through the display body
wall, and the return is at or above the water surface, there is no risk
of an overflow as with a sump from return lines that dip too low and
back-siphon in the event of an interruption of power (assuming the safe
running sump level was not calculated and obeyed). There is some
concern, however, with the protection of the pump intake: it is more
dangerous than small powerhead intakes. The literal placement of such
pumps is also somewhat to very inconvenient for servicing. It is for
these last reasons that I personally prefer to run a manifold off a
proper sump pump
With any external pump installation, please be absolutely sure to
use flanking slip unions (quick disconnects) and shut-off valves - see
illustration. This will allow fast and tidy removal of pumps for
cleaning, servicing or replacement. Neglect to heed this aspect of
proper installation has often resulted in many hours of hard labor and
frustration by aquarists that have hard-plumbed pumps inline and then
were faced with draining a tank to remove them.
In closing, by category, external direct drive pumps are admittedly
not quite as energy efficient as internal magnetic drive pumps
(powerheads). But, as previously stated, they are more durable
(regarding wear/abuse and lifespan), and they are more powerful
(operating against greater pressure/resistance/head). Yet, some modern
external drive pumps are remarkably efficient and competitive. They may
use less total energy overall than the number of powerheads required to
produce the same flow. At the very least, they will save money on
spared replacement costs over time (replacement of powerheads) and are
safe for the aquarist and its tanks inhabitants at large.
In this article, I hope to have succeeded in bringing to light an
inexpensive, discreet and effective DIY strategy for manipulating water
flow in the aquarium. If you find utilitarian merit in it, pass it
along to a friend and let's watch such techniques evolve in
time.