Veggie filter | A bog filter is a natural pond filter system

What is a Veggie Filter or Bog Filter?

A veggie filter (natural biofilter) is a separate water feature about 1 to 1 1/2 feet deep that is home to lots of aquatic plants (pond plants) that are deliberately starved of nutrients. In order to survive they absorb the nutrients directly from the pond water. These nutrients (nitrates) are present due to the activities of the Nitrogen Cycle, taking place in the fish pond.

Click here for unbeatable money saving offers on USA Pond Supplies and Pond Keeping Equipment in the UK, Guaranteed.

Once the dirty pond water has passed from the pond into the bog filter and then back into the water garden it has been purified. A plant filter is both cheaper to purchase and to run than a UV biofilter and it provides a natural eco system for your goldfish, koi and other fish to live in. It is however much more difficult to maintain.

How big should my veggie filter be compared to my pond?

  • Step 1: Calculate the pond volume -  Length x Width x Depth e.g. 10 ft x 10 ft x 10 ft = 1000 cu ft.
  • Step 2: Convert to gallons by multiplying by 7.48 - 1000 cu ft x 7.48 = 7480 gallon.
  • Step 3:  As a general rule of thumb the volume of your veggie filter must be at least 10% of the volume of your water garden or fish pond. If your pond is 1000 gallon then you need a plant filter that is 100 gallon ... obviously a bigger veggie filter of say (150%) or 150 gallon would be better if you have fairly large fish loads, particularly koi.

A veggie filter also known as a bog filter or plant filter is a natural pond filter system The best pond plants to use in A veggie filter?

There are many varieties of pond plants, categorized into six groups (water lilies, oxygenators, floating pond plants, partly emerging pond plants, marginals and bog plants). Some are more suitable than others, depending on factors such as climate, hours of sunshine, growth pattern and where your garden pond & veggie filter are situated.

In general, leafy plants that grow quickly are good bog filter plants. Azolla, also known as Fairy Moss grows extremely quickly and is capable of removing large amounts of nitrogen and carbon through photosynthesis ... Duckweed, classified as a floating pond plant is commonly used  and also acts as an occasional food and dietary supplement item for your goldfish and koi ... Water cress is well known for being a plant that consumes high levels of nitrate and would therefore be an excellent choice for your bog filter ... Soft rush / Pickerel rush / True bulrush or Flowering rush grow quickly for maximum biomass and are excellent for use in most bog filter applications ... Arrowheads are yet another species of aquatic pond plant that are ideal for your veggie filter ...  The Norfolk reed , classified as an oxygenator not only removes pollutants but because it's leaves are submerged below water allows oxygen to dissolve into the pond water and not into the atmosphere ... Pennywort, Water Hyacinths, Sweet Galingale and Water lettuce are popular choices too.

advantages of a veggie filter Over a UV pond filter

A plant filter is both cheaper to purchase and to run than a UV biofilter. It provides a natural eco system for your goldfish, koi and other fish to live in.

A plant filter provides both Green Water Control  (algae bloom) and Blanket weed Control (pond scum). The veggie filter plants compete directly with the green water and blanket weed for nitrates in the water. This natural pond filter system acts just like a pond UV filter in that it is both a biofilter + algae controller.

Disadvantages of a veggie filter Compared With a UV pond filter

Blocked pump impellors due to stray roots and foliage. A messy pond environment due to fish eating and damaging the plants. Bacteria and parasites live on plants and by introducing these into the pond you are in effect introducing potential problems. There is also the annual hassle of cleaning and maintenance (see below). I would personally opt for the slightly more expensive but low maintenance Biological Pond Filter + UV option.

Veggie filter maintenance and care

Your bog filter needs to be thoroughly cleaned at least once a year. This is usually carried out in the fall (September in the Northern Hemisphere). You need to remove all aquatic plants and clean them. They also need to be trimmed, tied back and divided before being placed back in the veggie filter. If you live in a cold climate you may want to store the plants over the winter months. Every good veggie filter should contain a bottom drain for clearing the waste and this should be opened every two to three weeks.

 

Click here for unbeatable money saving offers on USA Pond Supplies and Pond Keeping Equipment in the UK, Guaranteed.