Fish Ponds and Filtration Basics

For most people a pond is not complete until the addition of fish to add colour movement and interest. However fish ponds do require some form of filtration. Filtration does two important jobs. Firstly and most importantly it keeps the water healthy, and secondly if the correct package is chosen it will keep the water clear!

Therefore when planning a fishpond the most important concerns is the installation and positioning of the filter system.

The size and capacity of the filter will depend on the pond volume and the anticipated stocking levels. To calculate your pond volume, refer to pond volume page and for advice on choosing the size and type of filter please refer to the filtration page

When deciding on a filter you will discover there are two popular types 'gravity return' and ‘pressurized filters', each with their own benefits.

Gravity return filters, water is pumped into the filter and then is returned to the pond under the force of gravity. It is vital with gravity filters that the outlet is higher than the point of return, and for best results use a short length of rigid pipe slanting slightly downwards towards the pond as illustrated. This type of filter is generally cheaper than the pressurised models for smaller ponds.

Pressurised filters have become very popular recently. They will cope with small to medium sized garden ponds. Water is pumped through the filter under pressure allowing the water to exit the filter wherever it is required. This allows flexibility in positioning and overcomes the problem of gravity return filters having to be higher than the water surface. A number of these filters also come with easy cleaning systems reducing maintenance time and effort.

For larger ponds and ponds specifically for koi we stock a wide range of the latest state of the art specialist pump or gravity feed filters. Different systems have different advantages. Some use vortex chambers to settle out solid waste, some use screenex to filter solids which can then be flushed to waste, and some even have indicator lights to show when the filter needs cleaning!

Pump fed koi filters Usually multi-chambered units combining many media types from filter brushes to Japanese matting. The pump is positioned in the pond and the water is delivered into filter and returns to the pool under gravity.

Gravity fed filters Water is drawn into the filter by gravity but is pumped out by a pump positioned in the last chamber of the filter. The pipe work involved with these filters is more complex. Please ask for advice from one of our experts for further information.

GRAVITY RETURN FILTERS
Filter outlet must be positioned higher than the point
of return as water returns to the pond under the
force of gravity.

PRESSURIZED FILTERS
As the filter is pressurized the water leaves under pressure and may be delivered higher or lower in relation to the filter position.

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Fish Ponds & Filtration

Remember to consider filtration position during the planning stage.
Gravity return filters should be as close to the point of return as possible.
Seek advice on the correct equipment from our staff.
Ensure hose and cable routes have been considered.
Fish ponds should be at least 1.5 ft to 4 ft deep. (See "Depth")