Filtration, the Cleaning Machine and other Random Thoughts
by "The Phantom" (Ian McGuinness)
First published in Tank Talk, Canberra and District Aquarium Society, Australia
Aquarticles
In writing this article I am attempting to give some observations, information or
misinformation that I have collected in almost thirty years of killing, maiming and
sometimes doing the right thing by things aquatic.
FILTRATION
All filters work on one of three "types" of filtration or a
combination of several or all.
The types are:
a) mechanical
b) biological
c) chemical.
At present most filters work using biological and mechanical with some chemical thrown
in.
Mechanical filtration is the physical removal of debris,
waste products, uneaten food, dead fish or plants. They use a filter medium such as foam,
filter wool or sand/gravel to trap particles which are removed by later cleaning of the
medium.
Biological filtration relies on bacteria changing the nasties of
the nitrogen cycle (ammonia & nitrites) to less harmful nitrates. These bacteria need
to be "seeded" into a new tank by using old gravel, "black water"
(squeeze an old sponge filter), a commercial brew of bacteria (Cycle tm,
Biozyme tm or similar), or the bacteria in the gut of a
fish.
Chemical filtration changes the composition of some substances
in the aquarium. Ammonia absorbers, such as Ammogon tm help
prevent problems when water aging is done chemically (treatment with chloramine releases
free ammonia). Other "chemical" filtration includes ion exchangers which reduce
either carbonate or sulphur hardness. I am not convinced that these processes are
filtration. They are more a chemical reaction of converting one harmful substance to a
less "harmful" one or causing it to be precipitated out so it can be
mechanically removed.
The common types of filters are of two basic types - Internal and External.
Internal:
Undergravel filters are installed on the bottom of the tank and then
covered in gravel etc. The uplifts have an airstone (normally) which when connected to an
airpump push water up out of the airlifts causing water to be sucked down through the
gravel bed which contains bacteria that breaks down organic wastes. They are mainly a
biological filter with some mechanical thrown in. A layer of sponge or filter wool matting
can be placed on top of the plates then covered with gravel. This increases the bacterial
activity but can be a problem if the critters in the tank can burrow. Mulm (uneaten food,
fine solid particles etc) collect under and in the gravel and should be removed with a
gravel washer every month as a minimum.
Foam cartridges are generally run by an air pump and suck water
through a foam cylinder or other shape. Bacteria grow on the foam and provide biological
filtration as well as the foam trapping particles to provide mechanical filtration. The
foam should be removed frequently and gently washed to remove excess dirt BUT DO NOT go
overboard or you will remove/kill the good bacteria and lose the biological capacity until
the filter 'reseeds' (like new tank syndrome). Because the foam can trap small particles
of uneaten food I have used them in fry tanks where the fry pick at the surface to get a
smorgasbord.
Box filters normally use an airstone to force water up a tube
which causes water to be drawn through the 'box' which contains various filter media
(normally filter wool). A box filter should be cleaned as for a foam filter to keep it's
biological as well as mechanical filtration effective. A very 'dirty' box filter can still
be as effective but if it looks dark and slimy the bacteria is shot and a thorough clean
is needed. You can add mechanical 'aids' to box filters such as carbon and ammonia
removers as well as things to change the water chemistry. 1 have peat in the corner
filters in my Killie tanks to soften and acidify the water and run shell grit in other
tanks to cause the water to the more alkaline and harder.
Internal power filters are basically a foam filter in a canister
with a motor added to give greater water movement. Some have a hollow insert to which you
can add peat, carbon etc.as with corner filters. The cleaning is the same as with foam
filters and they use mechanical and biological filtration. These are a good system when
combined with water changes and gravel washing. I don't currently use these filters as I
try to hide all hoses, heaters and the like and if you have them behind rocks, plants or
other aquascaping they are hard to remove and you may get lazy and not clean them
regularly.
Powerheads are not filters by themselves but when added to foam
filters or used 'to replace the airstones to power under gravel filters greatly increase
the flow of water through these filters. They also create greater currents within the tank
helping to eliminate 'dead' spots and distribute the warmth from heaters. Most newer types
of powerheads have an outside airtube (or Venturi tube) which allows them to aerate the
outlet water (more air for your overstocked critters to try to breath).
The External filters include power filters, canister filters, diatom
filters and the impressive and costly trickle/sump filter.
The most common type of power filter I know hangs outside of the
tank with tubes drawing water out of the tank through various filter media (filter wool,
foam, carbon etc.) and then pump back into the tank via a spillway. I used these for many
years without any major problems until the number of tanks increased greatly. These
filters are normally very quiet and you can change and wash the filter medium easily and
use a combination of mechanical, biological and chemical filtration. Some minor problems I
have found are that the lids of the tank need to be specially cut (I always broke the
lid), sometimes the syphoning is hard to start (the new ones are generally self-priming)
and some of those stupid bastards in the tank tried to swim up the nice waterfall (some
made it - most either missed and ate carpet or got stranded on top of the foam etc and
croaked it there). Most now have a larger lip, some did not fit if you had edging inside
the tank, and the waterfall is lower into the tank and covered.
Canister filters are generally a closed container where the
water is siphoned into the filter body and forced through various layers of different
filter material. Bio-balls or ceramic pipes are normally the bottom layer and have great
surface area for those magic bacteria to grow on, then combinations of carbon, peat,
ammonia removers etc that can change or polish ' the water with either foam or filter wool
as the top layer to provide mechanical as well as biological filtration. The canister can
be hidden in a cabinet under the tank and only the inlet/outlet tubing is visible. The
return tubing can be attached to a spray bar to provide surface aeration. These filters
have eight to ten times the volume of an ordinary power filter but are about three times
the price. The major problem I have had is remembering to clean the beast (normally when
it is clogged with a drastically reduced ' water flow), but a sticker on a calendar helps
(as for dog/cat worrying tablets). The ease of disconnecting the canister is a problem but
a modest investment in quick release valves (make sure you install them to suit the
accessibility of your system) solves this. As with other filters using biological
filtration, don't overclean all the filter material at the same time.
Diatom filters are used to remove all sizes of matter from a
tank. They use diatomaceous earth to form a screen on a filter bag and water is sucked
through the bag with the grunge trapped on the outside of the bag. The flow rate is very
high and the filters are normally used for regular maintenance jobs, not as a permanent
single tank filter. I normally run these filters, depending on the tank size, for several
days to a maximum of a week (if I don't forget).
The last type I will try to describe is the trickle/sump system.
Basically water is removed from the tank and drawn through a series of different filter
materials. The major advantage is the size of the filter, it can be bigger than the tank
capacity. Bioballs are generally used to provide the biological filtration with
foam/filter wool giving the mechanical as well as additional biological filtration. Most
systems have a 'sump' at the lowest level where the mulm/grunge can be drained
off/syphoned out. Some have a rotating arm that sprays water from the tank onto the top of
the filter or you can have fixed spray bars (some of the old rotating arms had a tendency
to seize up and were fiddly to clean). In a marine system an algae scrubber can help to
eliminate phosphates and organic matter. A separate chamber can be used or the surface of
the filter wool used. You can help the algae get started by installing a light. In some
commercial systems the roof of the building is an algae pond only a couple of centimetres
deep that the water is pumped through. Sometimes even the 'experts' need help. I was shown
a 'great' system used in a Sydney aquatic display, and later over a beer was surprised
when she (the person who showed me the display, not the display itself complained about
the time and effort it took to get rid of the green algae on the surface of the sump
filter. I explained that cleaning that stupid algae out of the system may not be a good
thing as it uses some of the waste matter to grow, is helpful in removing phosphates, and
if it dies your system is in deep poo (several degrees and lots of marine biology didn't
teach everything).
MY SETUP AND SYSTEM
I will try to cover the filters and maintenance practices I use with some
advantages/disadvantages that I have found with them.
My current setup consists of over thirty tanks ranging from individual Betta tanks to
several 6' tanks in half of a tandem garage that is insulated with r2.5 batts in the
ceiling and walls. The individual Betta tanks do not have filters attached (or heaters),
the rest of the tanks have either undergravel (shock & horror!), corner (box) filters
or outside canister filters. Several small fry tanks have sponge filters. I have an oil
filled electric heater with a thermostat to keep the temperature above 15C.
Currently the undergravel filters (17 thereof) dominate, with corner filters (9) second
in number; then the outside canister filters (3). I also use 4 outside mechanical filters
(Vortex tm diatom).
One thing that I am very careful with is not to overstock my tanks, and not to overfeed
the critters (every two/three days with a variety of flake, pellets, frozen and live food
(with fry getting more frequent feeding)). These are two of the things that, no matter how
good the filter system, will eventually cause trouble if not watched.
I will start with the simple system used on my Betta tanks. These 'unfiltered' tanks
rely on cleaning by a diatom filter (mechanical) and water changes. There are currently 9
of these tanks with large quantities of water sprite, Salvinia, and duckweed. I try to do
some maintenance on these tanks every three weeks (lately it is every second month). By
having no gravel in the tanks it takes about 15 minutes for the diatom to clean all the
visible crap etc. from the water and 'polish' it. In a small tank the blast of the filter
can be almost overpowering for the fish in the Betta tanks so I give them a change of
scenery in an ice cream container while cleaning, water changing and plant thinning is
taking place. The filter has a 'fish guard' on it but as I know better than the
manufacturer I sometimes leave these off, thus getting better 'pulling' power (like a
nozzle on a vacuum cleaner) but it can also suck up fish and plants. I run these filters
for up to a week, but don't use them continuously, as a major cleaning aid. Other than
'fish sucking' (my fault but I usually blame the stupid fish) I have had some motors
'burn-out' (total replacement cost over 20 years $85.00), the occasional leaking seal, and
the one that caused all tanks to be banished from the house, when an inlet pipe fell out
of the tank onto the carpet causing the tank (4') to empty In about ten minutes (5 seconds
according to the disgruntled spouse - don't know why she's complaining, the carpet got
cleaned, maybe a little smelly, and the under floor heating system got flushed as well).
Now for the dreaded loved/hated undergravels. One of the 6' tanks, the 4 footers and
numerous 2 footers use these with some having a corner filter (peat & carbon) to
change the water conditions for specific fishes. Undergravel filters are primarily
biological that also trap stuff in the gravel bed. Probably the two most important things
to remember in running undergravels are:
a) Ensure the water is flowing through the gravel (I have seen lots of tanks with the
water level too low to allow the uplift tubes to 'pump' the water - no water flow, no
filtration).
b) Frequent cleaning of the gravel (don't remove the gravel and boil or hose totally
clean or you remove/kill the bacteria that makes the undergravel work). A gravel washer
works great as It also makes you do water changes. (Don't waste the water, pot plants etc
seem to thrive on the fish poop etc in the dirty water).
If you are into large scale rockscaping you can cause 'dead' spots under the rocks
reducing the effectiveness of the filter.
I have had a 6' tank containing South American cichlids running for nearly 9 years
without a 'total' pull-down and clean with the only filtration provided by air driven
undergravels with supplementary cleaning by the gravel washer and a diatom run for 2 to 7
days once every three months.
On the down side I have found that a tank filtered by an outside canister filter had
greatly improved plant growth than when it had undergravels. A 6' tank had been running
well, very few deaths (except for misadventure) for several years, but I converted its
filtration to a Fluval 303 containing Spaceballs, carbon/Ammogonä and sponge. The fish
were brought up to the same levels as before (many Tetras) with no change to the lighting.
The plants definitely grew quicker, thicker and generally better (except for Java fern,
which seemed to be much the same). Cabomba, some crypts, Bacopa, and
even Vallisneria. after a three month rest as the tank matured, have thrived to
the stage of being a nuisance in places.
Some of the smaller breeding/dead row tanks (mainly 2') have the simple yet effective
corner filter with different combinations of filter materials. I have found two minor
problems with these, one being that as an inside filter they need to be removed to be
cleaned (some people actually forget to clean them or think that they are self cleaning)
and they are a challenge to completely hide but let work. The system that I have set up in
several Canberra schools normally has one or more corner filters (cheap yet effective) and
the teachers clean the filters in the school term breaks (seems to work and a major event
prompts their memory). In my setup I try to assist the filters by doing gravel washes and
water changes monthly.
Several of my tanks have canister filters. These have worked well and I am using them
when I want a well-planted tank. The problems I have experienced were normally caused by
not taking enough care when setting up the filter after cleaning. In one case I had not
seated the motor seal properly and spent several days mopping up seeping water before I
did the job properly. Once one of the hoses was not connected well enough and water
sprayed over several power points causing a fuse to blow. On another occasion a very small
hole in a bendable hose was causing a fine jet of water to shoot 5' up into a circuit
board controlling half the lighting and tripping the heartsafe switch blacking out the
shed as well as the house. I only found this leak after resetting everything several times
and pulling the filter to pieces 1/2 a dozen times. When leaning over the tank on a wobbly
stool I got squirted in the eye and came close to joining the other Australians in the
tank!
I currently run two 'marine' tanks. The larger tank (tropical) has undergravels with
powerheads a large Eheim canister, and a protein skimmer. This gravel washes, water
changes and the use of diatom filter enables me to successfully (except when a 30Ow heater
stuck on and boiled the tank) keep an under stocked tank with shrimp, a moray eel,
damsels, clowns, some hard corals and anemones. The small tank is a cold water marine that
contains , several types of starfish, some unidentified baby fish (could be whiting, sprat
and herring) and, until it went for a walk and the ants got it, a small common octopus.
This tank has undergravel filters run by a powerful air pump to give extra aeration. While
this tank does suffer losses they are mainly due to predation.
All types of filters work, some better than others but they do require to be cleaned
properly and regularly. Regular water changes and gravel cleaning also help to maintain
the 'unnatural' system we attempt to keep our aquatic critters in.
On a closing and different note, people have questioned me as to the demise of
a much loved aquatic thingee, normally blaming the government, the greenhouse effect, the
evil eye and many others (they could be right) but some common causes are:
a) Lack of patience to allow a tank time to 'mature' (grow the good bacteria and cycle
out the ammonia, nitrites etc.) before adding the doomed critter. I allow a minimum of a
month for a newly set up freshwater tank, even with 'old' gravel, water, and pre-run
filters, before I add more than plants (in the second week) and any associated snails.
This gives the plants a chance to get established and play with other landscaping. This
month may be hard to take but when I have set up new marines it is two months before the
ONE conditioning fish is added then another three months before very low increases in
livestock are allowed. Someone (not me this time) that should have known better spent
three months getting everything to the right temperature, landscaped and fitters ticking
over nicely only to have a brainsnap and bought over FOUR HUNDRED dollars of freshwater
beasties only to see the system crash through overloading (like eating a barrow load of
laxative) and losing the lot.
b) The lovely creature that you must have is pox or other disease ridden (be very, very
careful, most sick fish from pet shops etc either die or kill your best specimen - YES I
have done this many times). A separate tank is the best solution but space and an
understanding partner are not always available. Look carefully at the thing you want as
well as the condition of other tank mates, it is sometimes better to defer the purchase
and return in a few days to see if all is well.
c) Overfeeding will cause the very best filtration system to collapse. Flake food is
great but it is a bit over concentrated and can form a smelly paste if uneaten. Some
'natural' food (vegetables such as peas, pumpkin or zucchini) or live foods that have some
'bulk' (I have not been able to get my critters to eat bran yet) are great to feed once or
twice a week in conjunction with the staple flake.
The final words of wisdom are to do water changes, (smell the water for chlorine if
doing more than a 15% change), clean the gravel, maintain the filter system, be patient
and enjoy the hobby.
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