The Garden Pond Filter Guide
Which Pond Filter Should I Buy?
There are several different types of garden pond filter on the market, varying widely in price and individual suitability. They all however, are designed to be the ideal residence and breeding ground of billions of bacteria, good bacteria! All these bacterial colonies need is a plentiful supply of Fish waste and oxygen.
They are known as Aerobic bacteria and colonize every available surface. This is why all pond filters are designed to use various types of pond filter media to provide maximum internal surface area. They all provide varying degrees of biological and mechanical capability. You could quite easily custom build your own homemade pond filter if you have the time and energy, if not there is a vast range to choose from. Here is an overview of the different types you may come across.
Gravity Return Filtration
This is a very simple filtration technique where the pondwater enters and passes through a mechanical agent such as foam or matting first to remove any solid debris. Next comes a high surface area biological media and exit back to pond via gravity. Can be cost effective but has the major downside that the filter exit must be above the highest level water return ie.waterfall. Can be placed next to the pond in a planted border or boxed in for seating etc to disguise it. Has generally been superseded by the pressurized option.
Ultra-violet filtration is used to kill algae spores, fungal spores, parasites and bacteria and is a very effective means of controlling green water and many fish diseases. They are rated in watts & come in many shapes and sizes. Many are now combined with bio/mechanical filtration, to offer an all in one filtration solution. The important thing to bear in mind with a UV pond filter is the flowthrough rate of the water past the UV light source. Too fast and the nasty critters your trying to eliminate will not receive a good fatal dose. Do not give yourself a fatal dose either, this type of UV light is VERY VERY BAD for your eyes. Never look at a lit bulb. (This wont be a problem if used according to manufacturers guidelines)
This modern technique works on exactly the same bio/mechanical filtration principles. However, it does have a couple of cool advancements. Because there is little loss in pressure as the water moves through the filter, the outflow can be directed upward through flexible piping to the head of a watercourse or other high feature. The body of the filter can be buried and easily hidden. The most cool advancement is ‘backwashing’. At the push of a button the solid waste is exepelled from the filter, much less messy maintenance. Magic! Some models even come with a cleaning indicator.
If you are interested in building a large pond for koi carp you will need to bite the bullet and invest in a good high quality koi pond filter system, these fish need and deserve sparkling clear water and it will greatly reduce your maintenance schedule. A good quality pond skimmer can also be utilized to keep an ornamental koi pond looking pristine. You may also find it worth investing in a pond vacuum if your pond is very deep. To make maintenance as easy as possible the best koi ponds have bottom drains installed, to easily flush water & debris away.
