Filtration, And The Different Types Of Filters For Your Pond
Having a good filter on your pond is an essential part of your ponds health and in turn your stress level. The better your pond functions, the less problems you will have, which makes your pond ownership much more enjoyable. There are many different types of filters, and it can be very confusing trying to choose the proper filter for your pond. This is mainly because many of us do not understand why we need a filter, and how they work. I have several videos on my YouTube Channel that help to teach about filtration, and look at different filter options.
Biological Filters
A biological filter is any filter that contains a media designed to grow and maintain a healthy and large bacteria population. The more surface are provided, and the better the waterflow thru it, the better the filter. These filters must be kept clean , as any sludge or debris buildup will hinder the growth of the bacteria. It must be an oxygen rich environment. See my video about the Nitrogen Cycle on the right side of this page to better understand biological filtration. Some examples of biological filter media are; Bio Balls, Beads, K2 media, and Matala.
Mechanical Filters
A mechanical filter, is any filter that is designed to remove solids out of the water. Things like as mud, algae, leaves, sand, fish and plant waste can be part of these filters collect. These filters are what keeps your pond and it’s water clean. A good mechanical filter should be in place before your biological filter, so that the water passing through your biological filter’s media is clean and free of debris that can build up and harm your bacteria. An example of mechanical filtration are filter pads. They are great for cleaning your water.
What Is The Nitrogen Cycle?
The Nitrogen Cycle is a process that occurs in your filter system that depends on bacteria to turn toxic ammonia into nitrites, and then nitrites into far less toxic nitrates. This is an important process that keeps your water safe and healthy for your fish and plants.
For more detailed information on the nitrogen cycle, see my YouTube video below. Every pond owner should understand this, as it is a key to your ponds success.
Filters come in many forms, and many contain different types of media. It is important to understand what the different types of media do, and how they are meant to function in order to understand how a particular filter works, and whether or not it is a good choice for your pond. Many of my videos on my YouTube channel help to explain how different medias work.
1.) Gravity Fed Filters
These are my favorite filter systems. I have used this system on every pond that I’ve built for the last 25 years. They utilize the use of bottom drains to feed water from the bottom of the pond, where all the debris settles, to a filter tank outside of the pond. An external pump is then used to pull clean filtered water from the tank, and return it to the pond.
2.) Bead Filters
Are pressurized sealed filter tanks where water is pumped in and flows through a large amount of filter beads, or similar media that is designed to grow bacteria for biological activity.
3.) Waterfall Filter Tanks
These are filters that are designed to be used at the top of waterfalls or streams. The water is pumped into the bottom of the filter where it then flows up through the media, then the water overflows over a spillway lip at the top of the filter. It provides an even sheet of water (providing it’s level), that then can flow down a waterfall or stream. These are effective filters, but sometimes hard to hide.
4.) Skimmers
Skimmers to me are a secondary filter to your main filter. Although, on a small pond, they can be used as a filter. They are very effective in removing debris from the top surface of the water. They will often include a removable net to collect the debris, as well as a filter pad to help keep debris from a submersible pump set into the skimmer itself. I often gravity feed the water into a larger filter tank with an external pump.
5.) Vortex Filter Tanks
Vortex filters are basically a round cylinder “cone shaped” tank that allows water into the tank on a side about half way down the tank. The water simply enters the tank, and flows continuously around in circles allowing the debris to slowly settle out of the water column to the bottom of the tank, where it can be removed.
These are just a few examples of the different types of filters that are available.
Ultra-Violet Sterilizers Or Clarifiers
These are units that can be added to a filtration system that can dramatically help to keep your pond water clear by killing algae. Water flows through the unit, past an ultra-violet bulb. the algae cells are exposed to UV, which can damage the cells, thus keeping your pond water from turning into “Pea Soup”. They are great alternatives to adding toxic algae killing chemicals into the pond that can be dangerous to your fish.
Choosing The Right Pump
Pumps are a key component of your filter system. They determine the amount of waterflow throughout your system. They are typically either external or submersible. The proper style depends on your system, and the equipment (filters) that are connected to it. The flow rate for different pumps will vary greatly. The proper flow rate for your pond depends on several factors, which should all fit hand in hand. Simply, the larger the water volume of the pond, the higher the flow rate of the pump, and the larger the filter should be to handle the flow rate of the water.
It is important to cycle as much water as possible through your filters in an effective, timely matter. The more you pass the volume of water through the filters, the cleaner and healthier your pond will be. But, be careful not to pump the water too quickly through a smaller filter, as it will not be filtered effectively. Always try to use a filter that is rated for a larger pond than you have. I believe that there is no such thing as “over filtering”.
Sizing a pump for your waterfall is something to consider as well. A general rule of thumb for a flow rate over a waterfall, is to have about 1,000 gallons of waterflow per hour, per inch of width of the waterfall. For example, a waterfall 24 inches wide, should be around 2,400 gallons per hour. This is just a guide, you may prefer more, or less.