Understanding Aquarium Filtration

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Understanding Aquarium Filtration

• Adapted from an article by Steve Rybicki

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Credits

• This presentation was adapted by Tamar Stephens
  from an article by Steve Rybicki. The text in
  this presentation is taken directly from his
  article, and is reprinted here with his kind
  permission.
• The article in its entirety can be found at
• http//www.angelsplus.com/ArticleFiltration.htm
• Clip art, photographs, and other home-made
  graphics were added for visual interest.

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How much do you know about aquarium filters?

• If you have a big enough filter, it is okay to
  overfeed your angelfish?
• What are the three kinds of filtration, and which
  one is best?
• Is a filter that creates lots of bubbles good for
  your angelfish?
• How does mechanical filtration threaten your
  angelfish?
• Can lots of filtration reduce the need for water
  changes?
• Keep reading to find the answers!

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Aquarium filtration is a bit of a mystery

• Aquarium filtration is a bit of a mystery to most
  people. There is a common misconception that the
  filter should take care of overfeeding and keep
  the water perfectly suitable for fish.
• Manufacturers make a big deal out of it. Most of
  the new filters coming to market are large,
  complex and expensive. The companies making them
  lead you to believe that if you are having
  problems with your fish, then it's probably due
  to the lack of filtration.
• You may be surprised to learn that the amount of
  filtration is the least likely cause of most
  problems. In this presentation, I hope to clear
  up the mystery and make this an easy concept to
  understand. Keeping your aquariums clean and
  suitable for fish is quite easy as you'll see.

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What are the three kinds of filtration?
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Getting down to the basics

• Let's get down to basics. You can filter water
  with three basic methods

CHEMICAL
MECHANICAL
BIOLOGICAL
Chemical reaction removes one or more impurities
Traps particles of waste
Nitrifying bacteria break down ammonia and
nitrites
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Most Filter Systems use a Combination

• Most filter systems involve a combination of at
  least two of these and some use all three. We are
  often led to believe that all are necessary, yet
  in my opinion only one is really important, and
  effective in most filters.
• Now let's take a more detailed look at each and
  how much sense it makes to incorporate them into
  your filtration methods.

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Chemical Filtration

• With chemical filtration you use an item like
  carbon or zeolite to remove an impurity.
• The chemical reaction that takes place is usually
  very short lived and it's effectiveness lessens
  rapidly from the very beginning of it's use.

What is activated carbon? It is carbon that has
been treated to make it very porous, thus
increasing the surface area dramatically.
Activate carbon works by chemically attracting
impurities, which adsorb (or stick to) the
carbon.
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Uses for Chemical Filtration

• In my opinion, unless you want to do an
  extraordinary amount of maintenance on a
  continual basis, this type of filtration is
  suitable only as a temporary measure.
• It's great for emergencies, removing medications
  from the water or trying to reduce sudden spikes
  of toxins.
• It's good to have some of these items on hand,
  but don't bother to incorporate them into your
  daily filtration system. In general, doing so
  would be a waste of time and money.

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Mechanical Filtration

• This involves the trapping and removal of waste
  particles. In concept, this is a great idea. In
  reality, most filters cannot do this in a manner
  that is effective or convenient for the aquarist.
  
• Most mechanical filters do a great job of
  trapping some particulate matter, but
  unfortunately they don't get it all. They have a
  tendency to move the water too fast, thus
  breaking the particulate matter into smaller
  pieces. The very small pieces tend to become
  suspended.
• These suspended micro particles contain the
  dangerous heterotrophic bacteria that can
  potentially cause great harm to our fish. The
  bacteria should be kept away from our fish, but
  these suspended particles do the opposite. They
  are in the water column and are very harmful.

Large particles may be broken into smaller
particles that pass through the filter and stay
suspended in the water column.
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Heterotrophic bacteria

• Heterotrophic bacteria primarily act as
  decomposers, feeding on dead plants and animals,
  and other organic material such as uneaten fish
  food in your aquarium!
• Under ideal conditions, heterotrophic bacteria
  can double their population in 15 minutes to an
  hour.
• Suppose you overfeed your fish in the morning, go
  to work, and come home about 10 hours later. If
  the bacterial population doubles every 15
  minutes, the population will increase by a factor
  of over 1 trillion!

Example of heterotrophic bacteria. Wikimedia
Commons (Public Domain)
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High speed filters are harmful

• Filters that move water through the aquarium at
  higher speeds, cause this problem to become
  worse. Small waste particles are the enemy.
  Filters that move water too quickly and those
  that create a large amount of small bubbles,
  break these particles into even smaller pieces
  and will actually cause this bacteria to become
  an even greater problem.
• To encourage small waste particles to settle in
  the filter chamber, water movement must be the
  slow enough to cause the particles to settle.
  This is very difficult to achieve with most power
  filters and canister filters.
• Very large aquariums or aquaculture systems will
  generally have large filter systems that contain
  proportionately large settling chambers, where
  these fine particles can be eliminated from the
  water column.

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Draw from the bottom of the tank

• In addition to removing these particles from the
  water column, they need to be removed from the
  bottom of the tank.
• The fins of fish often touch the bottom, and the
  waste particles that settle here can cause
  problems when the fish rubs against them.
• Therefore, a filter needs to draw from the tank
  bottom and anything it doesn't get, must be
  removed through siphoning.

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Biological filtration

• This is the process by which nitrifying bacteria
  break down ammonia and nitrites. I will not cover
  the basics of biological filtration. That is
  detailed in many other sources. Just realize that
  it is easy to have adequate nitrifying bacteria
  in aquariums containing ornamental fish.
• In intensive aquaculture, it is common to raise
  as much as 1 lb of fish per gallon of water, with
  relatively small biological filters. That would
  be equivalent to raising somewhere around 100-150
  adult angelfish in a 20 gallon tank.
• In such a system containing angelfish or other
  ornamentals, problems from dissolved organics and
  heterotrophic bacteria would destroy the fins or
  kill the fish long before ammonia or nitrites
  became a problem.

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A small biological filter

• A surprisingly small biological filter can handle
  the ammonia produced in the average aquarium
  containing ornamental species.
• So, although biological filtration is very
  important, it's also very easy to provide with a
  small inexpensive filter.
• The only requirement is that the filter does not
  clog so the nitrifying bacteria has constant
  exposure to oxygenated water.

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Tying it all together

• As you have probably surmised by this point,
  chemical filtration is not practical or effective
  for most aquarists.
• In addition, mechanical filtration is normally
  performed in a manner that can actually be
  detrimental.
• Unfortunately, most aquarists rely heavily on
  these and are not aware of the best way to
  utilize them. In fact, some of the most expensive
  filters can also be some of the least effective.

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Filtration Goal

• Your goal should be to get a filter that moves
  water slowly through a settling chamber, removes
  waste from the bottom, and one that is easy to
  keep from clogging.
• To accomplish this in an inexpensive manner on
  aquariums that are not part of a recirculating
  system, my recommendations for filtration are as
  follows.
• In aquariums that have a substrate, I recommend
  an undergravel filter. They are extremely
  effective and easy to maintain when setup
  properly. Their large surface area helps to
  reduce overall water speed and the area under the
  plates makes for a very effective settling
  chamber.

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Setting up an undergravel filter

• When setting one up, place the filter plates on
  the bare tank bottom.
• Then cover them with a layer of polyester
  batting. The batting will prevent the substrate
  from falling into the filter plates and it will
  also provide greater surface area for nitrifying
  bacteria. The quilt batting found in sewing
  stores works well.
• Cover with a substrate that is fine enough that
  no food particles can fall beneath the surface of
  the substrate. This will allow the easy siphoning
  of uneaten food that cannot be trapped.

Photo from http//www.drsfostersmith.com
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Clean the Gravel

• When doing a water change, use a gravel cleaner
  to remove particulate matter. Do this to no more
  than one half of the substrate during any one
  water change. Vary the location of the substrate
  cleaning with each water change.
• Using this technique, I've maintained beautiful,
  healthy aquariums for more than 20 years without
  ever having to add any addition filters or
  perform any other maintenance.

Photo from http//www.drsfostersmith.com
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Sponge filters

• For breeding operations or the raising of fry,
  bare bottom tanks should be used. In these
  situations, nothing beats a simple sponge filter
  for effectiveness and ease of maintenance.
• However, not all sponge filters are equally good.
  You must choose one with a pore size appropriate
  for the fish size being kept.
• The object is to keep the pores from getting
  clogged with food or fish feces. It should
  provide adequate surface area for nitrifying
  bacteria.
• The sponge type should allow easy rinsing of the
  filter. Yet, it must also allow space for the
  settling of organic debris.

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Bare-bottom Tank with Sponge Filter

• Juvenile angels in a bare-bottom tank with
  sponge filter.

Photo from http//www.angelsplus.com
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More on Sponge Filters

• If one sponge filter isn't enough, use more.
• Slow to moderate flow rates are essential. The
  smaller the filter, the slower the flow rate must
  be. The inside of the sponge becomes the settling
  chamber. Too much flow, and the settling chamber
  will not work.
• It is important that the sponge filter lifts
  water from the bottom of the tank. It not only
  makes it easier to get particles off the bottom
  and into the filter, but it turns the water over
  in the tank more efficiently for greater gas
  exchange. Therefore, the sponge filter should sit
  flat on the bottom.
• Those that are on a pedestal, may create dead
  spots in the aquarium, and are the worst at
  trapping particles that make it to the tank
  bottom.

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A Note about Filter Size

• Filters are not sized for a particular number of
  gallons of water.
• They work by consuming ammonia and nitrites
  produced by a particular bio-load. The bio load
  consists of the total mass of fish and
  heterotrophic bacteria in the tank.
• It matters not if the tank is large or small,
  filters have to be sized accordingly to the
  number and size of fish in relation to age, water
  temperature, pH and a few other factors. It is
  something you can only figure out for a given
  situation through experience.
• As long as the water isn't moving too fast in the
  tank, it doesn't hurt anything to over-filter,
  except possibly your wallet.

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Water Changes!

• So far, providing the needed filtration sounds
  fairly simple, but don't get too excited. One of
  the more important aspects of filtration can't be
  performed perfectly by any filter and is usually
  done manually.
• That is, the aquarist must periodically remove
  mulm with water changes, and they must also
  occasionally rinse the filters to keep them from
  clogging. Water changes are what is used to
  remove harmful dissolved organics and nitrates.
  Most aquarists worry about ammonia and nitrites.
  However, they are easily controlled and seldom a
  problem for anyone other than a beginner with
  poor husbandry practices.
• Dissolved organics and heterotrophic bacteria are
  the real concerns, yet they are almost impossible
  for an aquarist to detect. It is critically
  important to keep them at low levels. Water
  changes are the most effective way to do this.

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Cleaning Sponge Filters

• A note on how to rinse sponge filters Gently
  squeeze the sponge into fish-safe water (we use
  water taken out of the aquarium from a water
  change).
• Do not rinse it too thoroughly. You don't want to
  wash all the nitrifying bacteria out of it.
• Never clean them in a washing machine or
  dishwasher. This will essentially kill all the
  good nitrifying bacteria and render your filter
  useless.

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You can never do too many water changes!

• Water changes can even be used to remove uneaten
  food, but hopefully your fish husbandry is good
  enough that uneaten food doesn't exist.
• The frequency needed for water changes will vary
  greatly with fish density, temperature, amount of
  food being put into the tank, pH and a few other
  factors.
• It's better to err on the side of more water
  changes. You can perform too few, but never too
  many.

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Final Remarks

• It should be a relief to know that through the
  combination of properly designed sponge filters,
  correct feeding, and adequate water changes, you
  can filter an aquarium better and at lower cost
  than any other practical method.
• Don't fall prey to the hype surrounding expensive
  aquarium filters. There exists some very
  effective, sophisticated and expensive central
  filtration systems designed for hatcheries,
  however for practical filtration on individual
  aquariums, nothing works better than the simple
  filters recommended here.

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Enjoy your fish!

• Steve Rybicki

The End