NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/alt/aquaria/6672

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Path: sparky!uunet!cs.utexas.edu!torn!csd.unb.ca!UPEI.CA!speare
From: [e-mail] (Dr. David Speare)
Subject: Re: FAQ: Filters
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: University of Prince Edward Island, CANADA
References: <[e-mail]>
Date: Thu, 21 Jan 1993 13:04:47 GMT
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In article <[e-mail]> [e-mail] (Tony Li) writes:
>From: [e-mail] (Tony Li)
>Subject: FAQ: Filters
>Date: 1 Jan 1993 01:05:09 -0800
>                  Filters
>
>Rev 1.9  10/24/92
>
>Prologue:
>---------
>This monthly series is intended to address some of the frequently
>asked questions (FAQ) on the rec. and alt.aquaria newsgroups.  Because
>the answers may not be complete, please feel free to ask questions.
>This is only intended to address first level concerns, and not to
>dampen discussions.  Please see the file FAQ.README for pointers to other
>topics.
>
>Please review and send any corrections or inputs to the FAQ maintainers
>with "(FAQ)" in the subject line.  You are absolutely welcomed to tackle
>(i.e. WRITE) sections that have not been written yet.
>
>I've received recommendations to put email address "pointers" in
>the FAQ to vector questions to specific experts on particular
>subjects.  If you would like to offer yourself as such an expert,
>please send me your email address and the specific topics you want
>to host.  Please include an email path that is generally accessible
>to the greatest number of people.
>
>FILTERS AND RELATED QUESTIONS:
>------------------------------
>     Filtration is very important to the welfare of your guests,
>and as such there are many different kinds of filters.  Since there
>are many brands and opinions, one should post requests for
>recommendations.  Equipment that is typically found on advanced
>aquarists' systems are also noted.  These are typically more
>expensive, and are generally not needed by, nor recommended for
>beginners.
>     In general, if one needs to rinse/wash filter media, one
>should never use soap or hot water (or for that matter, very cold
>water).  This would serve to kill the beneficial bacterial colonies
>in the filter media.  (See nitrogen cycle).  Use the reject water
>siphoned out your aquarium to wash/rinse filter media.
>     The following filter discussions are arranged alphabetically,
>with related topics grouped arranged separately at the end.
>
>BUBBLE UP FILTERS
>     These are specific examples of internal filters.  These use
>streams of air bubbles to push water up and out of a tube, thereby
>creating a pull of water into the filter through the filter media.
>(See INTERNAL FILTERS).
>
>CANISTER FILTERS
>     These are large plastic "canisters" typically located outside
>of and under the aquarium in the cabinet. They are designed with a
>powerful pump which draws water through an in-take hose located in
>the aquarium, pushes it at a relatively high pressure through the
>filter medium, and forces it back to the aquarium through the
>return hose.  (Many times, this water is sprayed across the surface
>of the water to create aeration).
>
>CHEMICAL FILTERS  (advanced)
>     Ion exchange resins are used to deionize new water.  Also,
>synthetic resins designed to adsorb specific ions (like phosphates,
>or nitrates, or sulphates) are now available.  See ads in FAMA and
>other such magazines for new items.  Thiel has chapters on chemical
>filtration in his books, so does Moe (see Books).  Carbon is also a
>form of chemical filtration.
>
>DIATOM FILTERS  (advanced)
>     These can be described as purely mechanical filters.  It
>relies on the diatomaceous earth (skeletons of tiny animals called
>diatoms [di-atom = two atoms/parts]) which "cling" onto dirt and a
>fine mesh screen to capture the "dirty" diatoms.  Because of the
>efficiency, diatom filters are also called water polishers.  These
>are not used over long periods (they clog up very quickly), and
>hence cannot be considered good biological filters.
>
>EXTERNAL FILTERS
>     Oftentimes, this is used to denote power filters.  But this
>not always the case.  (See POWER FILTERS)
>
>FOAM FRACTIONATION
>     See PROTEIN SKIMMERS.
>
>INTERNAL FILTERS
>     These filters are plastic cartridges that fit inside the
>aquarium.  Dirty water is drawn into the filter through slits
>located on either the top or sides of the body.  The method of
>water propulsion can be motorized, or bubble driven.  Maintenance
>of these filters can be difficult.  Many times, as one lifts the
>filter out of the aquarium, dirty water backwashes out into the
>tank.
>     Some designs, like Lee's Triple Flow and similar models by
>Penn Plax and Marineland do not have this problem.  They also cost
>more, of course :-)  Also, one has to immerse entire appendages
>into the tank to access the filter.  This type of filter is only
>recommended for up to 20 gallons.  You may be surprised how
>inexpensive external power filters (EPF) can be and how quiet they
>are.  Always consider power filters unless you are raising fry,
>spawning live-bearers or killies in a "natural" setup, or need
>minimal flow (for spawning bubble-nest builders).
>
>MECHANICAL vs. BIOLOGICAL
>     Almost all filters perform mechanical filtration, and most
>perform biological filtration.  The difference between these is
>that mechanical filters will capture and remove suspended particles
>from the water, clearing the water in the process. (The filter
>media obviously becomes dirty, and must be cleaned every once in a
>while).  Biological filters provide habitats for beneficial
>bacteria that breakdown nitrogen compounds from biological waste
>into progressively less toxic forms (ammonia -> ammonium ->
>nitrites -> nitrates - > nitrogen).  (This is a gross over
>simplification.  See nitrogen cycle in H20 quality).
>
>POWER FILTERS
>     This is the common name for filters that hang on the back of
>the aquarium.  Two basic types exist.  In one case, water is drawn
>through siphon action into the filter media, and expelled by a
>pump.  In the second case, water is drawn by a pump into the filter
>media and the allowed to trickle back into the tank.  A major
>benefit of such a filter is the ease of maintenance.  The location
>and design of the filter allows for quick and non-messy removal of
>dirty filter media.
>
>PRE-FILTERS  (advanced)
>     This are filters used primarily to remove most of the
>particles from the water before it arrives at a primary filter,
>which may be located in a difficult to clean area.  The filter
>media on pre-filters are removed and replaced easily, thus reducing
>the number of times one has to change/maintain the media in the
>primary filter.
>
>PROTEIN SKIMMERS  (advanced)
>     Protein skimmers, also known as foam fractioners, are an
>unusual type of chemical filter.  They are primarily used in
>marine aquaria, because they require the formation of foam which
>form more readily in salt water.  Protein skimmers can be used in
>freshwater, but will be less efficient, and may require greater
>flows of air to produce sufficient foam.  They remove from the
>water a wide variety of organic compounds (e.g.. proteins) that
>normally collect on the surface of the tank water.
>     These compounds, surface active molecules, are attracted to
>the air-water boundary by their molecular structure.  Large amounts
>of these compounds are often visible to the aquarist as slicks,
>sheens, or thin scum on the tank surface.  In addition to the
>presence of films on the surface of the water, an abundance of
>these compounds is signalled by increased stability of bubbles
>floating on the water.  This stability can result in large rafts of
>bubbles spanning the surface of the tank, and very large bubbles
>grown from many successive merges of smaller bubbles.
>     A protein skimmer consists of a space where fine air bubbles
>are encouraged to mix with circulating tank water, and a means for
>collecting the resulting foam and removing this foam from the tank.
>Typically, a mist of fine bubbles is allowed to rise in a column of
>circulating water, forming foam in a small chamber at the top of
>the column.  This foam rises upwards through a narrow opening, and
>flows into a collection cup which must be periodically emptied.  In
>a properly adjusted protein skimmer, some amount of foam is present
>all the time in the chamber, but will only rise high enough to
>reach the cup and be collected when surface-active compounds are
>present in sufficient quantity to stabilize the foam.
>
>REEF FILTERS  (advanced)
>     See WET/DRY FILTERS.
>
>REVERSE UGF  (advanced)
>     This uses the same gravel plate as a regular UGF except that
>water is pumped down an uplift tube (in this case a misnomer),
>under the plate, and then *UP* through the gravel.  The water
>traveling through the uplift tube must be clean, since it would be
>very difficult to clean under the gravel plate.  The water can come
>from the output of a filter (canister filter for example), or can
>come from a new generation of powerheads (submersible centrifugal
>water pumps) has a "reverse flow" feature which makes it easier to
>use them for reverse flow UGF.  (See POWERHEADS).  The powerhead
>should be outfitted with some sort of pre-filter such as a sponge.
>     Since the filtration will have been taken care of already, the
>reverse UGF is primarily a biological filter.  It has the alleged
>benefit of keeping fish filth suspended in the water for the
>filters to suck up, and thereby reducing required maintenance on
>the gravel itself (i.e. dirt does not accumulate in the gravel).
>     Because most aquarium equipment was not designed to work in
>this manner, one typically has to rig up one's own hose adaptors to
>connect the output hose to the uplift tube.
>
>RO FILTERS  (advanced)
>     These purely mechanical filters that are used to purify water
>from the tap before introduction into the aquarium.  These devices
>use a thin membrane that only allows water molecules (and a few
>other smaller dissolved ions) to pass through to the output.  The
>unwanted water and materials are redirected to the drain.  This
>filtration method wastes water.  RO Filters can also be found at
>building supply stores since household drinking water filtration
>also uses the same technique.
>     There are two common types of RO filters sold.  One uses a
>cellulose tri-acetate (CTA) membrane, and the other uses a thin
>film composite (TFC) membrane.  The TFC membrane is the best for
>aquarium use.
>
>SKIMMER (see Protein Skimmer) (advanced)
>     This term can refer to surface skimmers as well as protein
>skimmers.  Surface skimmers are essentially boxes set just below
>the surface level of the aquarium.  Water "spills" into this box
>and is drawn out to a filter (by siphon or mechanical means).  This
>oftentimes removes the surface "slick" found on marine aquarium.
>
>SPONGE FILTERS
>     These are open cell sponges that are connected to some
>mechanical device (bubbler, power head, pump etc.) that will draw
>water into the sponge.  Because of the large surface area/water
>flow ratio, the suction is not strong enough at any given point on
>the sponge to trap fry or other small fish (as opposed to, for
>example, the intake hose of a canister filter).  These are often
>used for breeding tanks etc.  Fish filth is trapped in the sponge,
>which is rinsed every once in a while for maintenance.  Most
>sponges are shaped in such a way that, as filth clog up particular
>areas, the suction collect waste in other areas.  The sponge also
>serves as a biological filter.
>
>TRICKLE FILTERS  (advanced)
>     See WET/DRY FILTERS.
>
>
>TURNOVER RATE
>     The number of times the volume of water in the tank should
>pass through the filtration system in an hour.  The general rule is
>3-5 tanks/hour, unless the fish load is very light, in which case
>.5-1 tanks/hour is OK.  Cannister filter instructions suggest 1-2
>tanks/hour.  High turnover rates are probably beneficial (more
>filtration), as long as the fish are not swimming for their lives
>constantly.
>
>UNDERGRAVEL FILTERS (UGF)
>     This filter is a plastic plate with holes/slits that is placed
>first in the aquarium, after which gravel is poured on top.  Water
>is drawn through the gravel, and impelled up and out through uplift
>tubes (typically located in the rear corners of the tank).  The
>impelling method could be bubblers or power heads.  The gravel
>becomes the filter media for both mechanical and biological
>filtration.  This means that the gravel should be "vacuumed" every
>once in a while.  As the gravel becomes clogged, water bypasses the
>clogged areas, and these become sites for unhealthy bacterial
>activity.
>     There has been much debate over the use of UGFs.
>
>WET/DRY FILTERS (advanced)
>     These filters enhance the metabolic activity of the beneficial
>bacteria by providing good conditions for their growth.  These are
>very much in favor with marine aquarists, especially reef aquarists
>whose guests require clean stable water.
>     The principle of operation is as follows:  Water is sprayed
>(by a revolving spray bar) or trickled/dripped (by a plate with
>lots of holes) over a media that is largely exposed to air (i.e.
>not immersed in water).  As the relatively random patterns of water
>trickle over the media, the large surface of the media is
>constantly kept wet with a thin film of water.  The large surface
>area can dissolve lots of oxygen and may de-gas (expel) a number of
>other things, most notably ammonia (NH3) and CO2.  The media houses
>lots of bacteria which takes the oxygen and converts NH3/NH4+ into
>NO2- (nitrite), and NO2- into NO3- (nitrate).  This is the "dry"
>phase.
>     The "wet" section is a submersed media which can be one or
>both of the following: a purely biological filter, or a
>denitrification filter.  A number of sources have been suggesting
>that it contributes more to oxygen depletion than to any meaningful
>nitrification.  A denitrification filter is created by placing a
>large submerged sponge in the path of the water, allowing some
>water to *slowly* flow through the sponge, while most of the water
>passes over it.  In the nearly anaerobic cells of the sponge,
>nitrites are converted to nitrogen by Pseudomonas and other
>bacteria (however, Thiel and others have been very critical of this
>method of denitrification); chemical "augmentation" -- a dolomite
>or other calciferous material is used to leach calcium carbonate
>into the water to replenish  what gets metabolized by plants; and
>supplemental filtration, like a bag of activated carbon or some
>Chemi-Pure.
>
>     The water which is relatively depleted of oxygen, is passed
>into the wet phase, which supposedly converts the NO3- into
>nitrogen and some oxygen.  This water then gets pumped back into
>the tank.
>     Wet/dry filters are not cheap, and because of this, the net
>contributors often come up with suggestions for rolling your own.
>Keep your eyes peeled for these messages.
>
>Filtration Related issues:
>--------------------------
>
>AIR FILTERS
>     Some aquarists take the output of air pumps and bubble the air
>through water in a closed jar.  The air is then taken through the
>lid into the aquarium bubbler.  This serves to dissolve air borne
>chemicals (such as mineral oils from the pump) in the jar water
>before it gets into the aquarium.  Also useful for households that
>have smokers.
>
>GRANULATED ACTIVATED CHARCOAL/CARBON
>     These are small pellets of carbon manufactured from organic
>material (such as bones).  These pellets contain microscopic
>caverns that are the right size to trap certain molecules or ions
>(called adsorption as opposed to absorption).  After a period of 3-
>6 months or so, the carbon becomes ineffective.  It cannot be "re-
>activated" by heating in your home oven unless you have a blast
>furnace at home.
>
>OZONE
>     Ozone is a highly reactive form of oxygen, and it is bubbled
>through water in a special reactor to oxidize organic waste
>material and some toxins (rendering them less harmful).  Since it
>is so reactive, it is invariably bubbled through carbon (so
>leftover ozone forms carbon dioxide) before being released into the
>atmosphere.
>
>PEAT
>     This is an organic material made of composted forest fibers.
>Peat is rich in humic acid and tannin, and is sort of like tea.
>Its effect on water similar to tea.  It softens water and leaves
>the water slightly acidic (and yellow).  It is used for lowering
>and buffering water for sensitive fish.  Peat also helps chelate
>some metals and make them usable by plants.  There are two
>varieties of peat available: "normal" peat which consists of small
>particles (much like peat used in gardening) and *fibrous* peat
>that looks like a bunch of long strands and twigs (this is
>sometimes referred to as "German" peat and it is nearly impossible
>to buy in this country except in tiny, extremely overpriced
>packages of Fluval and Eheim brand in aquarium shops.
>     Garden peat can be bought dirt cheap in bulk from garden supply
>stores.  MAKE SURE IT HAS NO FERTILIZERS OR FUNGICIDES -- these will kill
>your fish.  According to Oleg Kiselev, Canadian peat, especially "Sunshine"
>brand, seems to be safe.  Oleg has also used "Black Magic" gardening peat
>with equal success.  ALWAYS RINSE PEAT BEFORE USING and many books
>recommend you boil it a few times, too.  Oleg usually boils peat 3-4 times
>and stores it wet.
>     Peat is very important for killifish spawning.
>
>POWER HEADS
>     These are miniature pumps that draw water through uplift tubes
>(associated with UGFs) and impel it into the aquarium.  They often
>come with a feature that allows air to be drawn into the outflow
>resulting in a fine mist of bubbles.  (This is due to something
>called Venturi action).  The water output can usually be directed
>in any direction, and up or down.  Some even have a reverse feature
>for Reverse UGF systems.
>     Although sometimes used as pumps, these are not really
>designed to push water up any distance.  They are designed to draw
>water and push it out laterally.
>
>UV STERILIZERS
>     Ultraviolet light sterilizers are used in series with  filters
>to kill water borne parasites (such as ich) and/or bacteria.
>Although not strictly a filter, it does ultimately remove harmful
>organisms.  When used in reef tanks or breeder tanks where the
>occupants depend on microscopic organisms in the water for food,
>these should not be turned on during feeding time.
>
>ZEOLITE
>     Zeolite is a naturally occurring mineral that can exchange
>"hard" metallic ions (like magnesium and calcium) for soft metallic
>ions (like sodium).  This softens water.  Zeolite also adsorbs
>ammonia.  Zeolite will not work in salt water.  It is reactivated
>by immersing it in a strong salt solution for 24 hours.
>
>POWER FILTERS
>
>A power filter is a box shaped filter that is hung on the back of an
>aquarium.  An intake pipe projects down into the tank and the output of the
>filter flows from spillway(s) on the body of the filter over the side of
>the tank and into the tank.  The other major type of filter that is similar
>to a power filter is the canister filter.
>
>Why use a power filter?
>
>1.  Space: These filters can be small relative to the volume that they pump
>    thru the filter.  They hang neatly over the side of the tank.  Most
>    people put them on the back, where no one can see them, and where the
>    space is wasted anyway.  *WARNING* All filters claim to pump a certain
>    volume per unit of time.  This figure is sometimes tested by using
>    clean (or no) filter media.  The actual volume pumped will start at the
>    published value and decrease to zero if the filter media is not cleaned
>    or changed.
>
>2.  Noise: Power filters seem to be relatively quiet compared to other
>    popular filters.
>
>3.  Cost: The initial cost for a power filter is low.
>
>4.  Easy of maintainance: Most of the filter media for a power filter is
>    available prepackaged (but at additional cost).  Power filters provide
>    easy access to the filter and media because it's part of the tank, in a
>    convenient location.  Disassembly of the filter is straightforward and
>    simple. Some filters will also allow you to insert media that was not
>    specifically designed for that filter.  Some filters are designed for
>    you to throw away your biologically active media if you follow the
>    manufactrer's instructions (this is bad, see below).
>
>Major Manufacturers of Power Filters
>    (GPH = US gallons/per hour).
>    Prices are approximate mail order prices in $US.
>
>        Name     GPH    $    GPH/$
>Aquaclear    Mini    100    10    10
>(Hagen)        150    150    14    10.7
>        200    200    14    14.3
>        300    300    21    14.3
>        500    428    38    11.3
>
>Whisper        Compact    100    10    10
>(Second Nature)    1    150    13    11.5
>        2    200    14    14.3
>        3    300    21    14.3
>        5    400    31    12.9
>
>Penguin        110    110    12    9.2
>w/biowheel    160    160    14    11.4
>(Marineland)    300    300    22    13.6
>
>Canistar    MX    155    18    8.6
>(Penn-Plax)
>
>Supreme Aquamaster PME     120     14    8.6
>        Aquamaster PMSW  ?      25
>        Aquamaster PLSW 300     29      10.3
>        Aquaking        300     32      9.4
>        Superking       600     41    14.6
>
>Overview of Perceived Performance.
>
>Mechanical Filtration/Chemical Filtration
>
>The key to mechanical and chemical filtration with a power filter is the
>amount of media that the water must pass through.  Ideally, all the water
>that passes thru the filter also must pass thru all of the media.
>
>The Aquaclear and Canistar filters should work the best at
>mechanical/chemical filtration.  They push all the input water thru all of
>the media.  The Aquaclear will allow water around the media if the media is
>clogged.  Look for backflow coming out near the siphon tube.  The Whispers
>and Penguins (except the Penguin 300) design allow some of the water to
>pass by the chemical filtration (carbon, ammo-chips etc.), but all the
>water must pass thru the dacron mesh.  The Penguin 300 has a "media
>basket", 2 removable containers in the filter body so you can add your own
>media to help filter the water, this design addition makes it difficult for
>any water to pass by the media.  The diatom water polishing mode on the
>Canistar seems to be iffy.
>
>
>Biological Filtration
>
>The main concern here is whether or not you throw away the bacteria's happy
>home when it comes time to clean the filter.  There is probably little
>difference in the performance of dacron vs. foam for harboring bacteria.
>
>The Aquaclear has a foam insert to harbor helpful bacteria.  You may rinse
>it and put it back in the filter, without ever buying new foam.  No helpful
>bacteria are lost if this is done correctly.  Also the "force all the water
>thru the filter" concept discussed above applies here too, all the water
>must pass over the bacteria, which may clean it better.  A caveat is that
>the fast flow through the sponge does lower the ability of the filter to
>get rid of NH4 in 1 pass, but the increased volume over a typical cannister
>filter may make up for that.  The Whisper's, Penguin's and Canistars'
>dacron pad eventually must be thrown out, thus losing the bacteria.
>Ingenious solutions have been invented to minimize this problem, but IMHO
>the Aquaclear is superior in this regard.  The Penguin is like the Whisper,
>except that it has an added device called a Bio-wheel.  It probably helps,
>but there are mixed reports on this.  The wheel may need regular,
>infrequent maintenance to prevent clogging.
>
>The Supreme models are unique in that they do not use the troublesome
>magnetic-impeller water-immersed motors.  Their motors are large industrial
>air-cooled ones that sit on top of the filter and run the impeller via a
>plastic shaft.  Also, they use siphon tubes to bring the water into the filter
>box, and pump the filtered water back to the aquarium, preventing the impeller
>from shredding and thus reducing the particle size in the influent.
>
>Other gotchas/Special features
>
>The Aquaclear has good sponge media, and allows the use of media bags so
>you can fill your own.  The carbon bags cost a bit, but they seem to use
>good carbon.
>
>The Penguin biowheel has a tendency to stop if it gets dirty.  If the wheel
>isnt' turning, it isn't working.
>
>Summary
>
>There are no clearly superior filters here, although the Whisper seems to
>lose in almost every category (your mileage may vary).  The Aquaclear
>series is probably the best overall, however, if you need a big filter, the
>Penguin 300 may be better because it has the Bio-Wheel and the media
>baskets.
>
>AIR PUMPS:
>----------
>
>Keep away from cheap pumps.  Make sure they are UL listed (as you should
>with all other electrical devices you are planning to use with your
>aquarium).  Listen to the pump (under load!) before you buy it.  If you can
>hear it in the noisy petshop, imagine what it will sound like in your
>silent house at 2 AM.  It is also a good idea to get a pump that is not too
>much more powerful than you need - more powerful pumps are invariably more
>noisy.
>
>As a general rule, "adjustable" air pumps are worth extra money
>only if the adjustment is electronic, rather than by a by-pass
>valve.  The former is more quiet.  Make sure your pump is
>positioned above the water level of your tank, because power
>failures and other events can cause water to back-siphon into the
>pump and flood it.  You can also use "check-valves" available at
>pet shops to make certain that this does not happen.
>
>The following is from Spass Stoiantschewsky:
>
>[e-mail]
>
>and the last name is spelled "stoiantschewsky", my system
>has it spelled wrong...always has, probably always will...
>
>the address will probably change, but i haven't the faintest
>idea when...it should have already changed...
>
>best pump tested at depth to date: tetra luft g
>best pump volume (shallow depth) to date: whisper 1000
>noisiest pumps: whisper
>quietest pumps: challenger (?), followed closely by tetra and
>silencer.
>
>best buy in pumps: tetra luft g
>
>noise level measurements are purely by ear.
>
>i'd like to talk to people who have pumps they particularly like
>or dislike and anyone who has pumps that haven't been tested (easy
>test).
>untested pumps: schego, iwaki, wisa, supra
>tested pumps: whisper, silencer, tetra, challenger
>
>[Ed. Note.  Spass will post a more complete article soon. ;-) ]
>
>CHILLER SIZING
>--------------
>
>Water Temperature Pull Down From Room Temperature (Degrees Fahrenheit) *
>               5o      10o      15o      20o      25o
>             ----     ----     ----     ----     ----
>Horsepower
>----------
>1/6           200      100       67       50       40
>1/5           560      280      187      140      112
>1/4           800      400      267      200      160
>1/3          1000      500      333      250      200
>1/2          1440      720      480      360      288
>3/4          2600     1300      867      650      520
>
>                      Tank Size
>                  ---------
>* Tank sizes represent the maximum volume for each horsepower and
>temperature combination.  To provide a margin of safety, add
>20 percent to the tank volume when determining chiller requirement.
>
>Reprinted with permission from _Aquarium Fish Magazine_, Vol. 5,
>No. 3, December 1992.
>
>
>Disclaimer:
>-----------
>Some answers listed above may reflect personal biases of the author
>and the FAQ's contributors.  In cases where the answers name
>specific products and their respective manufacturers, these are not
>to be taken as endorsements, nor commercials for the manufacturer.
>Where cost information is stated (magazine subscription rates),
>this is based on "street" information, and are in no way binding on
>the publisher.  The answers contained in this series pertain to
>discussions on the rec. and alt.aquaria newsgroups, and are by no means
>exhaustive.  This series is not intended to take the place of good
>aquarium books on the subject matter.
>
>Copyright:
>----------
>The FAQ owes its existence to the contributors of the net, and as
>such it belongs to the readers of rec.aquaria and alt.aquaria.
>Copies can be made freely, as long as it is distributed at no
>charge, and the disclaimers and the copyright notice are included.
>