Back to Back Issues Page
The Goldfish Gazette, Issue #003 -- Choosing The Correct Goldfish Pond Filter
March 31, 2014

Goldfish Care Tips and Guidelines

A Free Monthly Resource For Goldfish Enthusiasts
March 2014
Issue #003

In this issue
Choosing the correct pond filter
What’s new on the Website

Choosing a pond filter should be easy right?
When you start looking, you soon realise there is a huge confusing selection to choose from.
Not only is there different sizes of the same filter, there are also many different styles.
The trick in choosing the correct filter is to go back to basics.

Choosing The Correct Pond Filter

Choosing the pond filter that is going to suit your goldfish pond and save you work isn't as easy as it sounds.

There are many manufacturers offering all sorts of designs and options claiming their product is the best.

Some filters seem very cheap compared to other suppliers. Why? Should I have an internal or external filter? Should it be pressurized? Do I need a UV sterilizer?

It all starts to become confusing.

Ideally a filter should be considered when installing a new pond, but many only start thinking about a filter when the pond goes pea soup green or murky, spoiling the look and enjoyment.

All is not lost!

Start With The Basics

"The pond water volume should circulate through a filter every two hours."
So, for a 200 gallon pond, the pond filter must be able to handle 100 gallons an hour.

The first job is to calculate the water volume of your pond to give you some idea of the filter size you need.

Most filters come with a rating that states the maximum size pond they can filter efficiently. However, this figure is usually optimistic and assumes ideal pond conditions, for example low fish numbers and the pond is shaded.

I recommend that you purchase a filter twice the size you need. This builds in a safety factor to allow for filter clogging and various other reasons that always lowers the actual filtering ability of your filter.

If a filter rated at twice your pond's capacity doesn't keep the pond spotless, it will be because of one or more of the following reasons:

  • Fish numbers are too high (the most likely cause)
  • Over feeding
  • Too much sunlight
  • Too much debris finding its way into the pond.

Filter Types

Once you know the filter size you require, the next decision is what style of filter best suits your needs. It could be:
  • External (located outside the pond). Easy to get at for maintenance, but needs plumbing and hiding from view.
  • Internal (located inside the pond). Hidden from view but needs to be removed from the pond for maintenance.
  • An internal combined pump/filter. This type doesn't need plumbing.
Some filters come with a built in UV sterilizer or sometimes called a UV clarifier.

Filter Water Pumps

Most filters don't come with a water pump, so if you don't buy a combined pump/filter, you now need to find the right size pump for your pond.

Because you know the water volume of your pond, and therefore know how many gallons must flow through the filter each hour, it is relatively easy to work out the size of the pump you need.

Going back to our example of a 200 gallon pond, we know 100 gallons each hour must flow through our filter.

Unfortunately pond water pump ratings are like pond filters...on the optimistic side.
Like filters, I look for a pump that is rated for double the volume I require.

In summary, for a 200 gallon pond I would buy a filter rated for a 400 gallon pond, fed by a water pump rated at 200 gallons per hour.


What's New On The Website

Goldfish Pond Filters

Following on from this month's theme of pond filters, I have added a page that adds more depth on how to choose the right pond filter from all the options available.

Here is the link…Goldfish Pond Filters.

Pond Water Pumps

Most filters don't come with a water pump, so just when you think you have sorted your filtering requirements out, you realise you also need a pump.

I have added a page linking from the pond filter page that specifically looks at water pumps and how to choose the correct one for your filter.

Here is the link…Goldfish Pond Water Pumps.

Comments? Ideas? Feedback? I'd love to hear from you. Just reply to this e-zine and tell me what you think, or what topics you want covered.

Next Month’s Topic

Goldfish Pond UV Sterilizers - choosing the correct one.

Back to Back Issues Page