From: fungus@kira.csos.orst.edu (Curt Onstott)
Newsgroups: rec.aquaria
Subject: Calculating water pressure?
Date: Tue, 17 May 1994 06:33:58 UNDEFINED

I'm interested in building a wood/plexiglass aquarium. Is there a formula for
determining how strong individual components need to be? I want to build a
unit six feet deep x 3 feet wide and 8 feet long.

From: schurich@schenectady.ecn.purdue.edu (Scott R Schuricht)
Subject: Re: Calculating water pressure?
Date: Wed, 18 May 1994 14:42:06 GMT

In article <fungus.55.0039F80C@kira.csos.orst.edu> fungus@kira.csos.orst.edu (Curt Onstott) writes:
>I'm interested in building a wood/plexiglass aquarium. Is there a formula for
>determining how strong individual components need to be? I want to build a
>unit six feet deep x 3 feet wide and 8 feet long.

The pressure can be calculated using hydrostatics.

P-Po = r*g*dh

where P is the pressure you want to know
Po is a reference pressure - usually atmospheric pressure (14.7psia)
r is the density of water - 999 kg/m^3
g is gravity constant - 9.81 m/s^2
dh is the depth that you want the pressure at - 6ft

to get the total force on the side panels use

Force = 0.5 * r*g*w* h^2 where w is the width of the side.

This stuff will only give the force on the entire surface. For the 8 foot
side you will need to consider the bending (bow) of the material and I
don't remember that (it's been a long time :-). Good Luck !

From: qx01820@inet.d48.lilly.com
Newsgroups: rec.aquaria
Subject: Re: Calculating water pressure?
Date: 18 May 94 11:43:16 EST

In article <fungus.55.0039F80C@kira.csos.orst.edu>, fungus@kira.csos.orst.edu (Curt Onstott) writes:
> I'm interested in building a wood/plexiglass aquarium. Is there a formula for
> determining how strong individual components need to be? I want to build a
> unit six feet deep x 3 feet wide and 8 feet long.

I have'nt done any calculations, but your going to need minimum 1/2' acrylic
for this project. You are going to have to special order a 6 x 8' sheet though.
Standard dimension for sheet acrylic is 4 x 8'.
Use 1/2' exterior grade ply for the case, and build a 4x4 base to sit the whole
thing on. We built the base first, then permanently attached the case to it.
Create fillets in the corners with thickened resin, and put two layers of
fibergless matt on the inside surface, followed by two layers of cloth.
Sand any projections in the fiberglass that could harm the fish. You can also
use dyes in the resin to color the back of the tank, we used dark green.
Lay the tank face down on a bench, and put a healthy bead of silicone down.
Slide the face piece in through the top (this requires several people) and seat
it directly down on the bead. Let it set for 24hrs. minimum before you tip the
unit up.

Kai Schumann@Lilly.com

From: kevinc@kplace.monrou.com (Kevin Carpenter)
Newsgroups: rec.aquaria.marine.reefs,rec.aquaria.marine.misc,alt.aquaria,sci.aquaria
Subject: Re: [Q] 1500 gal. SPS Stony Coral Reef Tank--setup questions
Followup-To: rec.aquaria.marine.reefs,rec.aquaria.marine.misc,alt.aquaria,sci.aquaria
Date: 6 Oct 1996 21:04:40 -0500

Kohler (sk27525@swt.edu) wrote:
: I am making the preliminary arrangements (planning stages)for the
: construction of a 1500 hard coral aquarium into the wall of a home (which
: is also under construction). The tank will be approx. 18' long X 3' high
: X 3.5' wide, and will be located in the basement. The 'face' of the
: display tank will be set in the wall, and the sump and support equipment
: will located in a 'behind-the-scene' room accessible by a door in the
: same wall.

I had a similar 720g tank until last July, when I replaced it with a floor
level 2000g system.

I presume, at 18' long, that you will be doing some cross-bracing of the
tank. Keep in mind that top flexure will decrease by a factor of 8 every
time you decrease the unbraced span by half.

: I plan to use a 2000 lbs of live rock in this setup (mostly
: aquacultured Florida rock [if avail.], with some Carribean, Fiji, and
: Marshall Islands rock). A bilayer live sand/argonite/plenum

All of my rock is Florida based (purchased several years ago before the
ban). You will have an interesting time filling such an aquarium with
the small rock typically sold. The bulk of my rock is in the 20-80lbs
per piece catagory. I feel that large tanks look better with large
rocks. Of course, you could build up an artifical infrastructure and
just layer the surface with commerical rock.

: denitrification system will also be utilized. Yep, I'm aware of the
: cost, and its not a problem for this project. The home is located on the
: coast of Southern Florida, and natural seawater will be pumped in for
: water changes/initial tank filling. The water collection pipe will
: extend a hundred yards into the ocean (SG 1.021), and the water will be

1.021? Are you sure? I was under the impression natural saltwater was
a lot closer to 1.0255. In any case, you would want that (1.025-1.026)
for hard corals since the relative concentration of calcium and other
minerals is higher at higher SG.

: Now the questions--filtration, wave making, lighting, and
: fish-coral compatiblity. First filtration. I plan to use use two
: sumps--I'll discuss each sump filter individually. Water from tank
: overflows will be directed to 3 or 4 six foot tall protein skimmers, and
: then directed to a large green microalgae filter (lit w/ VHO daylight
: bulbs). Next, the water will pass passively over several pounds of
: carbon, and then to a twin, multilevel biological tower filter
: (constructed with tinted acrylic). The H2O leaves the carbon area and
: flows down into a fluidized biofilter, and from there down into a wet/dry
: filter (to reoxygenate the water after it leaves the highly efficient
: oxygen demanding fluidized filter). From there, the water flows into an
: empty settling region of the sump (where detritus can settle and be
: vacuumed up w/ a diatom filter). Finally, the water reaches a live rock
: nursery section of the sump (lit by metal halide/VHO actinic), where
: additional nitrification/denitrification can occur and baby corals can
: grow undistubed by the tank's fish inhabitants. The water then is
: returned to the display aquarium. Note that there will be two such of
: the sump systems described above, and I want them to filter the entire
: system's water volume ten times per hour! Evaporation will be compensated
: by reverse osmosis/DO water replacement via a kalkwasser reactor (which

I presume you mean RO/DI... Use a tandom DI cartridge.
: will direct its output into the sumps). Note that in these sumps
: organics are removed (via heavy skimming, algal turf filtration, and
: carbon) from the system before they can be metabolized by the bio
: filters. Will this plan work? I know this is not a traditional
: Berlin/Jaubert system, but I'm attempting to compensate for the prescence
: of several large fish (see below). Chillers and UV sterilization will
: also be used. Any suggestions/comments would be appreciated.

Well... I'd use the UV on your ocean water to kill any pathogens, but not
routinely on your tank since it would take out any desireable plankton.

: What type of lighting should I use, and how much of it? I assume
: I'll need metal halide (10,000K?), and I plan to utilize VHO actinics.
: How many of the above will I need to support SPS stony coral growth
: (mostly Acropora sp.)?

I use (6) 400W fixture over my 2000g tank. I used (4) over the 720g. I
could use more... I'm glad money isn't a problem, since annual replacement
of bulbs alone cost about $40 a month. Then there is the electric bill.

: How can I set up a wave-making system? Should a use multiple big
: Iwaki pumps w/ a wave generating controller? How can I maximize water
: circulation/flow over the live rock?

I'm fond of Carslon Surge Devices.

: All specimens will be added to the tank as juveniles, and the
: triggers, angelfish, lionfish, and grouper will be introduced last. Note

The triggers, lionfish, and grouper will enjoy eating everything smaller
than themselves.

: that while 20 + Acropora sp. corals will stock the tank, but no soft
: corals, anenomes, crustaceans, or mollusks will be added to this
: aquarium. Will the triggers or angelfish cause undue damage to the
: Acropora in a tank this large? Thanks!

You mentioned wanting to move 15000 gallons an hour. Thats 250 gpm or
about a 3-hp pool pump. Presumming you have 220V power available, you
will be drawing about 20 amps at 220V. Hmmm, typically pool pumps are
most common up to about 1.5 HP, so lets assume two in use. Oops, they
also don't like to run in lower pressure applications, so lets drop
down to (3) 1-hp units. My 0.75 HP pump I used on the 720g draws 11.5
amps. Lets just say your (3) untils will draw 4KWs between them. Add
another 2KWs for lights and an equal amount for cooling (all power used
will eventually become heat). Now we have daytime draws of 12 KW or
abit over 100 amps at 110V. Best check your electrical service, since
thats a quarter of many homes 200 amp 220V service. Assuming 10 cents/kw,
you will also be spending on the order of 4*24(for pumps)+2*12(for lights)+
6*12(for cooling, assuming 50% duty cycle) = 192kwhours or about $20/day
in electricity.

I've found my tanks evaporate about 1% of their volume per day, so plan
ventilation for 15 gallons of water a day. Don't even THINK about using
a dehumidifier on this scale.

As another poster mentions, plan around the ability to service your tank.
I replaced my 720g after 3 years in large part to my inability to adequatly
clean it without excessive effort.

Good luck, and I hope your serious given the time others have invested in
replying to your post.
--
Kevin Carpenter
(Expressing his comments from home, where this message originated)