Pond Filter Buying Guide

An adequate pond filter system is essential for the survival of aquatic life in your pond. Discussed below are some issues that generally arise when shopping for one.

Size of filters

'The bigger the better' - this is what applies when it comes to size of pond filters. But never the less, in order to estimate the size of your pond pump and filter you need to first analyze your pond volume which is the amount of water that your pond can hold in gallons or liters. This can be found through manual calculations or by using a pond volume calculator. You should have knowledge about the length, width and depth of your pond in either case (diameter if your pond is circular). If your pond is of irregular dimensions, you can make use of average length, width and depth instead.

The size of pond filter can also be estimated using the surface area of the pond.

In addition to the pond volume or surface area, you should also estimate the type and quantity of wildlife your pond has. For instance if you pond has large fish stocks and special fish like Koi then your filter size should be bigger.

Calculating Filter Size using Pond Volume

Typically, it is recommended that the size of a filter should be 15% to 20% of the volume of the pond if your pond has large stocks of fish or has Koi. In other cases 10% to 15% would do fine. (The size of the filter here means the surface area of the filter)

Calculating Filter Size using Surface Area

If you are using pond surface area then it is recommended that the size of the pond filter should be at-least 1/3rd of the surface area of the pond. In case your pond has a large stock of fish or has Koi then the size of filter can be at-least one half of the surface area. (The size of the filter here means the surface area of the filter)

Table1: Formula for calculating Surface Area of the pond

SHAPE OF POOL	FORMULA FOR GALLONS	SURFACE AREA FORMULA
Rectangular or square	length x width x depth x 7.5	length x width ÷ 9
Circular	diameter x diameter x depth x 5.9	1/2 the diameter squared (times itself) x 3.14 ÷ 9
Oval with straight sides	length x width x depth x 6.7	3.14 x 1/2 length x 1/2 width ÷ 9

What kind of Garden Pond Filters to Use?

There are many kinds of pond filter systems like pressurized pond filters, top side pond filters, tetra pond filters, bioforce pond filters and more. The kind of garden pond filter to use is entirely dependent upon the nature of your garden pond. If you have an ornamental pond that has aquatic plants but no wildlife like fish you can decide to settle for a mechanical filter that will take care of plant and tree debris. Aquatic plants will take up nutrients in the water which means there will be less chance of any algae growth. You can also make use of bog filters that can offer biological filtration naturally.

For back-yard garden ponds that have fish it is extremely important to make use of a biological filter media along with a mechanical filter. This can be coupled with a UV filter to best results. For the initial period until the biological filter matures, the pond can be clarified using a chemical filter.

If your garden pond does not have either aquatic plants or wildlife you can simply decide to forgo any filter. Algae growth can be dealt with directly using algaecides which are extremely effective. Plant debris can be removed manually or can be prevented from falling on the pond using a pond net. You can also consider going for simple home made pond filters or do it your self pond filters.

Related Reads
Things to Consider while Buying a Pond Filter
Types of Fish Pond Filters