What is a Bog Filter or Veggie Filter?
A veggie filter is a plant filter that provides a natural eco system for your goldfish, koi and other fish to live in. It is home to lots of aquatic pond plants that are deliberately starved of nutrients. In order to survive they absorb the nutrients directly from the pond water.
Once the dirty pond water has passed from your garden pond into the veggie filter and then back into the pond it has been purified. Veggie filters are however much more difficult to maintain than a fish pond with a biological pond filter.
What Size veggie Filter Do I Need?
- Calculate Pond Volume ... Length x Width x Depth e.g. 10 ft x 10 ft x 10 ft = 1000 cu ft.
- Convert to gallons by multiplying by 7.48 - 1000 cu ft x 7.48 = 7480 gallon.
- As a general rule of thumb the volume of your veggie filter must be at least 10% of the volume of your garden pond. If your pond is 1000 gallon then you need a plant filter that is 100 gallon; a veggie filter that is 150% is better if you have a high fish stocking density.
What Are The Best Pond Plants To Use?
Some pond plants are more suitable than others, depending on factors such as climate, hours of sunshine, growth pattern and where the veggie filter is located. Leafy plants that grow quickly are good veggie 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.
Veggie Filter v Pond Filter Advantages
- A plant filter is both cheaper to purchase and to run than a pond filter.
- It provides a natural eco system for your goldfish, koi and other fish to live in.
- A plant filter provides algae and blanketweed control. The veggie filter plants compete directly with the green water and blanket weed for nitrates in the water.
Veggie Filter v Pond Filter Disadvantages
- 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.
Veggie Filter Maintenance
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.
The full article can be read at http://www.garden-pond-filters.com/veggiebio.htm, where you will find other interesting articles and product resources.
