So, you’ve decided to build a pond—and now you’re starting to realise that you may need a pump and filter. Then reality hits: there are so many filter brands and opinions on the market that it quickly becomes confusing.
Before choosing a filter, the first and most important question to ask is:
Does your pond actually need a filter, or can it get by with simple water circulation?
Let’s start with the basics.
Why Filter a Pond?
Imagine being stuck in a room you can’t leave.
There’s no toilet, no shower, and no ventilation. The windows are sealed shut, rubbish can’t be taken out, and the bin keeps filling up. You’re still being fed every day, and—naturally—you still need to eat and produce waste.
It doesn’t take long before that environment becomes unpleasant, unhealthy, and unsafe.
This is exactly what happens in a pond without proper filtration.
Fish produce waste, uneaten food breaks down, plant debris accumulates, and harmful compounds build up over time. Without filtration, water quality deteriorates, stressing fish and other living organisms.
Filtration removes waste and toxins, helping to create a cleaner, healthier, and more stable environment where pond life can thrive long-term.
Fish Load and Waste Production
The more fish you have in a pond, the more waste is produced. How quickly this waste builds up depends on several factors, including:
- Fish species
- Number and size of fish
- Feeding frequency and food quality
A properly sized and well-designed filter removes this waste and keeps it out of the main body of water, preventing it from harming fish or disrupting water balance.
For this reason, any pond—regardless of size—that contains fish should strongly consider installing a filter.
If you’re unsure what your pond requires, Sydney Pond Services is always happy to help you assess your setup and recommend a suitable solution.
How to Choose the Right Pond Filter
Now that you understand why filtration is important, the next question is:
What type of filter do you need?
Most pond filters fall into two main categories:
1. Pressure Filters
2. Gravity Filters
Each filter type requires a compatible pump to function efficiently, so it’s important to consider both together.
Every Filter has got corresponding pump that best suits them (insert link for Pump Choices) so it is important to understand that as well.
Now let’s talk about pressure filters
PRESSURE FILTERS
Pressure filters are one of the most common filters in the market nowadays with brands like Oase, Aquascape, Pondmax, Hoselock etc
These pressure brands use the same principle when it comes to filtering; water is forced under pressure through bunch of filter materials and you get filtered what being returned back to the pond
These filters are most commonly used because they are easily installed. The are not limited with positioning and distance (though it is always advice to have your filter as close as much as possible to your pond). They can also be installed above or below a pond (though there are limitations still). It is however better to talk to us at SydneyPondServices about your specific scenario before making the decision.
Pressure filters are well sort after. However, they do have their limitations
Pros of Pressure filters
- They are not limited with positioning, so it easy to hide them during construction.
- Most of these types of filters come with integrated UV (ultraviolet) Clarifiers. This is an excellent add on because it takes away the stress of having to constantly prevent your pond from going green. Unicellular algae grow rapidly in Ponds that are expose to sun feeding off nutrient. Clarifying is the easiest way to keep them under control.
- Majority of pressure filter have a backwash mode which makes it easy to clean. Remember that once a filter is saturated with waste, it will need to cleaned. If this is not done, your pond water quality will deteriorate rapidly. The frequency of cleaning depends on individual pond which require building a maintenance schedule. Speak to us and we can provide a service or help guide you through generating a maintenance schedule (insert link on maintenance).
These attributes make the pressure filter a highly desired filter. It is however also important to understand their limitations.
Cons of Pressure filters
- Pressure filters have limitations on the amount of waste they can hold at the particular time, hence the need to regularly backwash. This is because most have them are shaped as a bucket with limited space to trap materials.
- For Ponds that are more than 5,000 litres, it is advice you use combination of the largest series in pressure filters.
- It is not advice to install pressure filter more than one storey (more than 3 meters below the pond level).
For further inquiries please seek our guidance via contacting us.
GRAVITY FILTERS
Gravity filters are the best in terms filtration capacity and longer time between full filter cleans. They have a bigger holding capacity for good bacteria population. Good bacteria are the key in providing chemical filtrations. Hence, the more filter materials are in a filter, the more surface is available for good bacteria colony to grow thus gravity filters have an upper hedge over pressure filters. This has to work with the right water flow provided by the pump. So, it’s important to match the right pump (Link ‘pump’ to the Pump blog).
This makes gravity filter excellent for large ponds (more than 5,000 litres) and have a better capacity to filter pond with large number and size of fish, like goldfish and koi.
Pros of Gravity filters
- Better capacity for good bacteria growth provides excellent mechanical (particles) and biological filtration (water chemistry –pH, Ammonia etc)
- Better capacity means longer time with clean outs. During design, back flushing system can be integrated making cleaning very easy.
- It can handle large fish load with waste.
- UV canisters can be integrated to give extra assurance that green water algae will be kept under control.
Cons of Gravity filters
- It’s very difficult to hide gravity filters. They need to be located above the water level. This makes location a little bit difficult but if you can find a suitable location for them, they will definitely do the job. Speak to us for guidance on specifications.
- It usually takes longer to clean since it holds more waste over extended period of time. However, if you do clean them out with a schedule, then it wouldn’t matter if it takes longer.
As you can see, gravity filters are better in terms of filtration but pressure can also work, it just depends on what suits you and your pond location. Speaking with us at Sydney Pond Services can help guide you on the best way to build the pond and give your pond the best outcome in terms of filtration.
Other filter types are :
Bog filters
all in one pond filters (with UV)
and Wetland filters – for large to dam sized pond
Every type of filter can be used to suit different size of ponds.
It is important to talk to an expert before making your final decision. Get it right from the start.