Why does my filter smell when I open the lid?

Get your questions answered

Everything you ever wanted to ask about ponds

Building a pond is an exciting project but it can be complex. If you’ve decided to build a pond then we’re sure you’ll want to create something that’s:

  • beautiful to look at
  • well-built and strong
  • the perfect ecosystem for your fish and plants

If you get it right, a well-built pond will be a joy for years to come. Here are some of the questions AQUAPRO’s customers frequently ask. If you have further enquiries, please contact us for more information.

Rules and regulations

First things first

We understand that once you’ve decided to build a pond, you’ll want to get cracking right away. However, before you start, it’s advisable to contact your local Town or Shire Council to find out if they have an approvals process. There are different regulations in each State or Territory and can even change from Shire to Shire.

It’s important to know upfront what (if any) restrictions your local authority has in place for above or below ground ponds and if your pond requires any type of fencing or child safely grids. Once you have established your obligations, it’s time to start planning.

It's a pond, not a puddle

  • Filtration and why it’s important

    Filtration is essential for a crystal clear pond with happy fish. Creating the right balance for biological filtration is easy with the right equipment and know-how. Your local Bunnings Warehouse will have a range of pumps, filters, equipment and treatments to make sure your pond is in good health and looks great.


  • Can I join my pond liner?

    Yes, it’s possible to make a strong, watertight joint using special PVC liner glue. EPDM liners can be joined using primer and double-sided tape. It’s easiest to do this on a flat surface like a driveway or paved area.

  • What should I consider when buying a pool liner?

    Buying a cheap liner is false economy – the last thing you want when you have spent weeks building, establishing and populating your pool is for it to develop a leak. A good quality liner that is made for Australian conditions is essential for your pond to look great and for longer lasting performance.

    AQUAPRO top tip – never buy a liner before your pond base is dug out or built. This will ensure you don’t have either a costly shortfall or wasteful excess.

  • What is the best building material for my pond?

    Ponds may be constructed from a variety of different materials, the most common being:

    • PVC or EPDM liner
    • Concrete
    • Fiberglass or preformed plastic ponds

    Advantages and disadvantages to all options include the initial outlay, installation cost, availability and suitability for the pond you’re planning.

    Because there are so many variables, it makes sense to talk to the pond expert at your local Bunnings Warehouse to see which product is best suited to your own specific requirements.

The science

  • Why does my filter smell when I open the lid?

    It smells because the bacteria is doing its job. A good working filter will produce nitrogen gas as one of its by-products, which means it’s working well.

  • Are the bacteria in my filter harmful?

    Not at all, the bacteria naturally occurs in all natural water systems.

  • How does a pond filter work?

    Biological filtration performs a process known as the nitrogen cycle. In this cycle, organic pollutants that enter the pond via fish waste, decomposed plant matter or excess fish food are converted from toxic to non-toxic substances using oxygen and bacteria.

    If the harmful substances are not broken down by oxygen and bacteria then algae will grow and fish death can occur. It’s the same process that occurs in aquariums, just on a larger scale.

Good to know

  • When should I think about a filter?

    When you’re planning your pond, you should also be planning your filtration because you will have more choices. Even if you can’t afford to buy a filtration system right away, at least plan for it in your construction and then you can install one when your pond becomes established.

  • Why isn’t the filter on my pump keeping my water clear?

    The small sponge filters found on the front of some pumps are only designed to stop particles damaging the moving parts (impellor) of the pump. They are not designed to clean water. If you have one of these filters and have to clean it more than you’d like, you should consider an AQUAPRO Prefilter Sponge or possibly even an AP5000 UV Pressure Filter which will dramatically reduce your maintenance.

  • How long will my filter pads last?

    Every pond is different and the life of your filter pads will depend on where your pond is located and your specific circumstances. A good rule of thumb is that you should get at least two years out of your filter sponges and replacements are available.

  • How many hours a day does my filter have to run?

    A biological filter must run 24/7 to sustain the bacteria and oxygenate the water. This is why pond pumps with low power consumption, such as the AQUAPRO’s range of energy efficient submersible pumps are recommended for filtration systems.