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Overview
Filters
come in all shapes, sizes and prices. Ponds can be without filters or high tech
systems that operate on timers and remote controls. To help you decide which
filter you need or not, let's cover the types that are available:
Pre-Filters--Can be a wire or plastic cage, or even large pieces of rock in a
container. The main function of a pre-filter is to keep large debris and leaves
out of your pump impellers. The larger the surface area the longer it will take to
restrict water flow.
Particulate Filters--Can be made from foam, cotton batting, Japanese matting,
scrubbies, Vortex settling tanks, anything that will trap particles. 2 or 3
stage filters are not uncommon and use progressively finer materials to
accomplish waste filtration. All-in-one filters i.e. sponge types with
bio-media, or bead type filters will work at their optimum when partially
clogged, because finer particles are filtered.
Chemical Filters--Pressurized containers, for optimum flow through
characteristics, that actually change water chemistry by additions of Activated
Carbon, Zeolites, or resins etc.. Using non pressurized containers will work,
but only at a 26% efficiency compared to pressurized.
Biological Filters, Trickle Filters--Can be made out of any suitable container,
packed with media such as scrubbies, PVC shavings etc. that will allow maximum
surface area for Bacteria to come in contact with the cleanest water possible,
to expose the bacteria to maximum Oxygen and food. The water should flow thru,
rather than across the media and should be above the pond rather than submerged
to allow the maximum surface area and oxygen absorption possible. More oxygen
will allow the bacteria to multiply and convert the harmful chemicals faster. In
these systems, beneficial oxygen loving bacteria, colonize any exposed surface
area to speed up the nitrogen cycle, converting harmful Ammonia and Nitrites to
Nitrates.
Order--The order listed should be the order these should be employed in your system,
i.e. you should have pre-filtered and particulate filtered water, before it goes
thru your bio-filter, otherwise the beneficial bacteria will get covered
with mud and debris and cannot survive.
All in One Bead Filters--All
in one bead filters will work only if you let the particles accumulate enough to
clog some of the inside filter media. So in that case you want to run the filter
longer before back flushing 2-3 days to two weeks depending on the fish load.
Longer if the filter is new.
The downside is that you're only getting some biological filtration and some
particulate filtration. A frequent problem would be clogging of the filter
material to the point of having to open the filter and manually flushing out all
the crud--not much fun and time consuming and water use intensive. Some units do
a better job than others when backwashing. Some bead filters come with blowers,
air compressors that you turn on briefly during the back flush process. If you
are lucky, these compressors can extend the complete cleanout period to several
years.
You could add a pre-filter to your pump intake, an inexpensive but labor
intensive option that will always leave some particles in the pond when you
clean it. Or, if you have a skimmer, add more and denser filter pads so it will
trap the particles. Or add an oversize leaf skimmer filled with filter material
just before the pump. In those cases all of the bead filter becomes a biological
filter since nothing will impede the flow of oxygen and food to the beneficial
bacteria.
Veggie Filters--Veggie or plant filters are our imitation of a natural
filtration system. If built correctly, veggie filters will do all of the
above type of filtration except chemical. One serious drawback, however, is
their inability to correct filtration problems quickly. You will have to wait
for the plants to grow before you have an effective filtration system. Another
drawback is the lack of filtration in the cold months, since most of your plants
will have gone dormant. It is possible, however, if you keep good records and
have good knowledge of plant growing cycles, to keep veggie filters operating in
anything but the coldest months, with only bio and particulate functions.
Water
Changes--10% weekly water changes (more if the pond is overstocked) will do
wonders for the longevity of your pond creatures. If you've never thought of
water changes as a filter, you may wish to rethink that position. Water changes
will do everything a filter can do, plus you are removing harmful waste products
and built up toxins. When changing water, always draw from the bottom of
your pond, especially if water circulation is not optimum and the pond has little
coves than can stagnate water.
Ultraviolet Lights--U.V. Lights filter nothing. They destroy floating Algae
spores,
otherwise known as "Green Water", that flow past the U.V. bulb.
Medicinal Grade U.V's will destroy bacteria, but are way too expensive to use in
a pond environment. Algae blooms, or green water, indicate a lack of filtration,
overstocking, poor filter maintenance, lack of water changes, overfeeding or all
of the above. While U.V. lights can be used as a temporary fix for green water, the dead Algae has to be removed from your pond via mechanical
filtration, as it will deteriorate and further rob the pond water of valuable
Oxygen.
Summary
In general, none of these filters, are needed in a pond, but do serve to enable
us to keep fish longer and healthier. A filter forces you to remove the waste
products when it's cleaned.
Freshwater fish, including domestic Koi are
incredibly hardy creatures and can survive for years at less than optimum
conditions, but bad water conditions are the number one reason of dead or
diseased fish.
On a non filter system, water testing,
water changes and large water volumes in relation to stocking densities, are of paramount importance
to allow you to stop problems before they happen. Be aware that in a non
filtered system, over time, depending on your stocking levels and debris
influx, the debris build up in your pond will rob the water of Oxygen,
lower your Ph levels, build anaerobic sediment, and reduce Kh levels.
This will require complete pond cleanout much more frequently than in a
filtered pond.
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