Bead Filter for Koi Pond

Pond Filtration is Necessary for Maintaining Healthy Water For Your Koi Fish

When it comes to koi pond filters, there are a lot of different options out there. Bead filters are a biofiltration system that works to keep your pond clean using natural and safe ways. The filter media inside are beads made of low-density polyethylene, a common plastic. 

Bead filters have been used for many years, since the 1970s when fish farmers used biofilters to raise game fish and food in Idaho. Since koi fish are bottom feeders, when they disturb the sediment at the bottom, bead filters easily capture the small debris particles and rapidly remove them from the pond. The koi fish and the biological filtration system work together to create a clean environment. 

In this article, we'll look at what a bead filter is and how it works. It's also important to know where it is located and how to manage and maintain it to ensure it keeps your koi pond clean for a long time. 

Here is a quick breakdown of what we'll be talking about in this article: 

  • What Is A Bead Filter?
  • Where Is It Located? 
  • How Does It Work? 
  • Pros & Cons
  • Conclusion

What Is A Bead Filter? 

A bead filter is a biological and mechanical filter that uses plastic beads to clean out the pond water. The beads can both filter and provide clarification, which is the process of separating and removing solids, such as large debris, dirt, and small particles, from the water. It is a pressurized chamber that contains thousands of tightly packed beads, creating a mechanical filtration system. 

Bead filters for koi ponds were created to fix many of the problems that sand filters had. Sand filters would sometimes cause cloudy water, and they required replacing every so often. Sand would also drift into the pond as the water pushed through the filter media, contaminating the pond and creating more debris. 

The density of the bead filter media traps solids and allows clean pond water to pass through with little head loss. It also creates an area for nitrifying bacteria to attach and break down toxic wastes from the fish. The beads never need to be replaced since they are merely stopping solid debris from going past. 

Where Is It Located? 

Pressurized biological filtration systems have the most flexibility when it comes to placement. You can hide the unit behind a waterfall or tree outside the pond, bury it in the ground, or put it inside a shed farther away. The pond filter attaches to a hose that goes to the back of the pond. The filter's inlet also needs to connect to the pump inside the pond to receive adequate power. 

Koi pond bead filters will also need an outlet to flush out wastewater during the cleaning process. You can either simply let the water jet out or attach a hose to transfer the water to a drain or another area of your backyard. 

How Does It Work?

A bead filter uses bacteria that can break down any debris created by plants, fish, or the natural environment. It does not add any harsh chemicals but filters the water naturally and safely by allowing beneficial bacteria to grow. 

The beads trap any fine particles as water flows through. As pond water is pushed through the unit by the pump, the beads trap fine particles and allow the water to flow through. The ammonia level in water naturally increases as fish create waste. Still, the bead filter keeps the ammonia level stable, balances the chemical levels in the water, and promotes a healthy ecosystem. 

Though the beads do not need replacing, it does require regular cleaning. This can be done by back-washing the system. All you need to do is turn the filter off, stir the beads to let the solids drift to the bottom, and then drain it out. 

Pros & Cons

Though there are many benefits to a bead filter system, there are some downfalls too. Here are some of the pros and cons of the bead filter for you to consider before deciding if this is the right pressurized filter for your pond. 


One of the best things about a koi pond bead filter is that it uses natural ways to keep the water clean, thereby creating a healthy environment for fish. It also does not need to be replaced, though it requires cleaning after some time. Fortunately, the cleaning process is straightforward and does not require you to open the unit or get your hands dirty. 

Bead filters use less water and do not clog easily, especially in comparison to sand filters. It captures dirt and other solid debris, preventing water from clouding or darkening. This pressurized filter also uses a bypass system, allowing you to use a low-pressure pump and saving you a lot of energy overall. 


Though you may use a low-pressure pump with a bead filter, you will need to buy another filter for pre-filtering to capture the larger solids. Though a bead filter can trap small particles, it cannot trap larger debris like trash or leaves. The added filter can be expensive compared to other filters that do not require a pre-filtering unit. 

You also need to clean out a koi pond bead filter somewhat frequently to ensure it does not build up too much and create murky waters. It can be a labor-intensive process for some. Even after back flushing the system, you never know how thoroughly you have rinsed out the unit since you do not need to open it. 

Frank Salvatore

In 2015 our family moved into a house south of Denver, Colorado with a  koi pond.  Since that time I've learned to really enjoy the koi fish and the pond. This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?

About Me

Hey there - I'm Frank Salvatore. In 2015 our family moved into a house south of Denver, Colorado that had a Koi pond. The problem was I knew absolutely NOTHING about koi ponds.

This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?
Learn More About Me

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