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FAQs

How do I determine the correct size filter for my pond?

Begin by calculating your pond’s volume (length × width × average depth). Most filters should process the total volume at least once per hour. For example, a 2,000 L pond needs a filter rated at ~2,000 L/h. 


If you have koi (which produce more waste), aim for more frequent turnover - ideally every hour. 

What types of pond filters are available and how do I choose the right one?

Pond filters fall into several key categories, each suited for different setups and needs:

  • Pressurized Filters: Enclosed units that maintain pump pressure, ideal when you want to hide the filter or locate it away from the pond edge. They’re easy to maintain but offer quicker water flow, which may reduce filtration time.
  • Box (Flow-Through) Filters: Open systems that allow slower water flow for improved sedimentation. Best positioned at water level since they rely on gravity to return water to the pond.
  • Koi & Multi-Chamber Filters: Advanced box filters (such as Nexus models) designed for heavy bioload ponds, especially koi ponds.
  • Internal / Submersible Filters: Installed inside the pond; compact and unobtrusive but can be harder to access for maintenance.
  • Gravity-Fed & Pump-Fed Filters: External setups positioned above or level with water—some use gravity to return water; others rely on pump power. 


Match the filter type to your pond’s size, stocking level, and aesthetics. Pressured units suit hidden installations; box or koi filters deliver better filtration for heavily stocked ponds.

Are solar pond pumps a good option?

Yes, solar pumps offer energy-efficient and eco‑friendly operation, perfect for small, sunlit ponds. However, they may underperform on cloudy days or during early morning and evening. For reliable year-round operation or larger ponds, traditional electric pumps remain the most consistent choice.

Submersible vs external pumps - which pond pump should I use?
  • Submersible pumps sit directly in the water—easy to hide, install, and maintain.
  • External (dry-mounted) pumps sit outside the pond and are ideal for larger systems, especially those with high head requirements or complex plumbing 

Choose a pond pump based on the visual impact, access, and performance you need.

What is “head height” and why does it matter for my pump selection?

Head height refers to the vertical distance water must be lifted, plus the equivalent resistance caused by pipe friction or length. As head height increases, flow decreases. For instance, a pump rated 1000 GPH at 0 ft head might only yield 500 GPH at 10 ft. To size for a waterfall, multiply the width of the spillover (in inches) by 100–200 GPH per inch at your required head height

Can pond liners be repaired if they get damaged?

Yes - small tears or punctures (e.g., from sharp tools or debris) are easily fixed. Use a repair patch kit or compatible adhesive (specific to the liner material, e.g., EPDM or PVC), following the instructions to ensure a watertight seal. For extensive damage, replacing the affected section, or installing a full liner replacement, might be advised.

Do I need an underlay beneath my pond liner?

Absolutely- pond liner underlay adds essential protection. It cushions the liner, shielding it from sharp rocks, roots, or rough ground and can significantly extend the liner’s life. We offer quality Pond Liner Underlay that’s affordable insurance against punctures and wear.

How do I choose the right size of pond liner for my pond?

Measure the maximum length, width, and depth of your intended pond shape. Then, allow extra overlap (typically 20–30 cm) on all sides to accommodate trenches, edging, and anchoring.

For example, a 2 m × 1.5 m rectangular pond that's 0.6 m deep would need a liner roughly 2.6 m × 2.1 m.


If you'd like, we can assist using our Pond Calculator tool for precise sizing.

What are the main differences between EPDM, Butyl, PVC, and Firestone pond liners?

Each liner material offers unique benefits:

  • EPDM (Ethylene Propylene Diene Monomer): Highly flexible and tear-resistant, ideal for irregular or complex pond shapes. Long-lasting and weather-resistant.
  • Butyl Rubber: Slightly thicker and more robust than EPDM; excellent puncture resistance and UV stability—great for installations with potentially abrasive edges.
  • PVC (Polyvinyl Chloride): Lightweight and cost-effective, but less flexible over time - best for simpler, rectangular ponds where ease-of-installation matters.
  • Firestone EverGuard EPDM: Premium-grade liner known for exceptional durability, heavy-duty strength, and longer lifespan - perfect for larger or high-traffic ponds.
How often should I clean the pond?

Ecosystem-style ponds are mostly self-cleaning, but a yearly clean-out is still recommended. Filters need maintenance every 2–4 weeks during the season (sponge rinsed in pond water).

Do I need planning permission to build a pond?

Usually not - for typical garden ponds you won’t need permission. But always check if it’s large, in a public site, or within a conservation area.

Will a pond attract wildlife?

Absolutely! Even small ponds support frogs, toads, dragonflies, insects, and birds. To encourage them, include sloping edges and a mix of aquatic plants.

What's the best way to manage algae blooms?

Ditching the algae isn’t just about chemicals - it’s about addressing the root cause: nutrient overload. Use aeration, added beneficial bacteria, and consider natural nutrient binders.

How often should I clean my pond filter?

Clean your pond filter every 2–4 weeks during peak season, or when you notice a drop in flow rate. Always rinse sponges in pond water, not tap water, to preserve bacteria.

Can I use tap water in my pond?

Yes, but it’s best to treat tap water with a dechlorinator first. Chlorine and chloramine in tap water can harm fish and beneficial bacteria.

How deep should my pond be for fish?

A pond for goldfish should be at least 60cm (2 feet) deep. For koi, a minimum depth of 90cm (3 feet) is recommended to protect them in cold weather.

What’s the difference between a pond pump and a fountain pump?

Pond pumps (also called filter pumps) are designed to circulate water to a filter or waterfall. Fountain pumps are made to create decorative sprays and may not be strong enough for filtration.

My pond item is out of stock – when will it be back?

If an item is out of stock, it’s usually on order and due back soon. You can contact us or sign up for stock alerts on the product page for updates.

How can I keep my pond clear without chemicals?

A healthy pond can stay clear using good filtration, the right balance of plants and fish, regular maintenance, and avoiding overfeeding.

What size pump do I need for my pond?

As a general rule, your pump should circulate the entire volume of your pond once every hour. Use our handy calculator to see what your pond volume is. Need help? Contact us!

Do I need a filter for my pond?

Most ponds benefit from a filter, especially if they contain fish. Filters help keep the water clear and healthy by removing debris and breaking down waste. We have many types available, from gravity filters to pressurised, koi filters and solar!

How can I clear green water in my pond?

Green water can be cleared using a UV clarifier, improving filtration, and adding plants that absorb excess nutrients like oxygenators and lilies. You can also use a treatment to tackle issues with green water.

Why is my pond water green?

Green pond water is usually caused by algae. This can happen if there’s too much sunlight, not enough filtration, or an imbalance in the pond’s ecosystem. 

When is the best time of year to start a pond?

The best time to start a pond is in spring or early autumn when temperatures are mild and conditions are stable. This gives plants and wildlife time to settle in before extreme weather.

What is the safest way to get rid of my old equipment?

We know it’s tempting but please do not throw old electrical equipment in your bin. Please see this specific article on our WEEE Directive.

How long will my refund take?

It can take up to 14 working days for items to be checked and and refunds processed.

Why doesn’t my equipment have a plug attached?

Please see the pond electrics page in our help and advice blog for information on plugs.

I have an issue with my pond, can you help?

If you have a problem with your pond, equipment or would simply like general pond-keeping advice then we will be happy to help!

  • Check out our Blogs to see if your query is covered
  • Talk with our experienced advisors on LiveChat
  • Send us an email to info@pondkeeper.co.uk
  • Contact our call centre on 01642 370888 – all of our operators are trained and will be able to assist with any query you may have
My product is faulty, what can I do?

Please contact the team at your earliest convenience to discuss a resolution.

How do I return an item?

Please see our Returns page for detailed information on this.

What payment methods do you accept?

We accept Visa, MasterCard, Maestro and PayPal on the website. We accept Visa, MasterCard, Maestro and American Express over the telephone.

Can I amend my order?

Absolutely, provided we have not already despatched it. Please contact us and one of the team will be happy to help.

The item I want is out of stock, when will it be back?

We usually have estimated delivery dates for incoming products, please contact us for specific product information.

I need my order delivered on a weekend, is this possible?

Saturday & Sunday delivery is available for some items. Prices start at £20.00. Please contact us to discuss this option.

How much is delivery?

Our standard delivery charge is £4.99. Some orders will require additional postage, please see our Delivery page for further information.

How long does delivery take?

We place 99% of our orders on a Next Working Day service. If your order is placed before 1pm then you will receive your order the following working day. Please see our Delivery page for further information.