Retro Fit Weighted Bottom Drain

Retro Fit Weighted Bottom Drain

The Retro Fit Weighted Bottom Drain adds low-level suction to an existing pond without cutting through the liner, fibreglass or concrete base. Its weighted, freestanding body sits directly on the pond floor, while the 1.5 inch pickup connection allows it to feed a suitable pond pump or a compatible secondary pump inlet.

It is a practical answer for ponds that were built without a conventional bottom drain, or for systems that would benefit from an additional draw point close to the pond floor. By pulling water from low down in the pond, it can improve circulation and help move settled waste and suspended debris towards the mechanical filter.

A bottom drain for ponds that are already built

A traditional 110 mm bottom drain is normally installed while the pond is being constructed. The pipework passes through the pond base and feeds a gravity filtration system, so adding one later can involve major structural work. This weighted retrofit drain avoids that disruption. It can be positioned on the existing pond floor and connected to suitable pump suction pipework.

This makes it useful for established koi ponds, formal ponds, holding systems and larger garden ponds where a permanent drain was not fitted. It can also provide a second low-level pickup where the existing circulation leaves an area in which debris tends to settle.

Why choose this weighted retrofit drain?

• Adds a low-level suction point without cutting the pond base
• Weighted construction helps the drain remain on the pond floor
• Low dome draws water and debris from around its perimeter
• 1.5 inch pickup connection suits common pond plumbing
• Can feed a suitable internal pond pump, a compatible secondary pump inlet or an external pond pump designed for the installation
• Useful for existing ponds where a built-in gravity drain is not practical
• Can be lifted out for inspection or repositioning when the pump is isolated

How the Retro Fit Weighted Bottom Drain works

Water is drawn beneath the perimeter of the dome and leaves through the pickup connection on top. The low inlet gap helps reduce the chance of larger fish reaching the suction opening while allowing water and mobile debris to be pulled from the pond floor.

The drain does not create suction by itself. It must be connected to a correctly sized pond pump or to a pump with a compatible second inlet. Actual performance depends on the pump, hose or pipe diameter, run length, lift, fittings and the shape of the pond. Keep the pipe route as short and unrestricted as practical.

Pump-fed retrofit drain, not a 110 mm gravity bottom drain

This is an important distinction. The product is intended as a pump-fed suction drain with a 1.5 inch connection. It is not a substitute for a built-in 110 mm gravity bottom drain on a new high-flow koi pond. Where the pond is still at the construction stage, a properly planned gravity drain will usually offer greater flow and more direct waste transfer to a drum filter, sieve or settlement system.

For an existing pond, however, this weighted drain can provide a useful improvement without rebuilding the base. If you are comparing both approaches, browse our full pond bottom drain range.

Choosing the pump and pipework

Use a pond pump that is designed to accept an external suction connection or a compatible secondary inlet. Some submersible filter pumps allow a second suction source, while suitable dry-mounted pumps may also be used where the manufacturer permits a flooded suction installation. Always follow the pump manufacturer’s instructions and never run a pond pump dry.

The pickup is nominally 1.5 inch, which is approximately 38 mm. Check the actual hose, adapter and pump connection before ordering because nominal pond hose and rigid pipe sizes are not automatically interchangeable. The hose must be secure, kink free and appropriate for suction use. Browse heavy duty flexible pond hose, stainless steel hose clips and our pond filter pumps when planning the complete connection.

What is included?

• Weighted freestanding drain body and dome
• 1.5 inch pickup connection and stepped adapter shown in the product image

Not included: pond pump, flexible hose or rigid pipe, hose clips, valves and any pump-specific adapters. These should be selected to match the individual pond and pump installation.

Technical details

Product type	Weighted retrofit pond bottom drain
Supplier code	PW6342
Connection	1.5 inch pickup, approximately 38 mm nominal size
Installation	Freestanding on the pond floor
Filtration arrangement	Pump-fed suction connection
Pond base penetration required	No
Aeration	Not included
Typical use	Existing koi ponds, formal ponds and larger garden ponds

Installation guidance

1. Switch off and isolate the pump before working in or around the pond.
2. Choose a low, accessible position where debris naturally settles and where the hose will not obstruct fish or maintenance.
3. Connect the correct 1.5 inch hose or adapter and secure every flexible connection with a suitable stainless steel hose clip.
4. Lower the weighted drain carefully onto the pond floor. Do not drop it onto the liner or fibreglass surface.
5. Route and support the hose so that it cannot kink, float, rub against sharp edges or place strain on the drain and pump.
6. Restart the pump and check the flow, drain position and every connection. Inspect the pickup regularly and clear any leaves, blanket weed or debris that could restrict it.

Every pond is different. Positioning, pump choice and pipework have a major effect on the result, so plan the complete route before cutting hose or fittings. If you are unsure whether this drain is suitable for your pump, send us the pump model and a few clear photographs of the pond and equipment.

Frequently asked questions

Do I need to cut the pond liner?

No. The drain is weighted and sits on the existing pond floor, making it suitable for retrofit use.

Is this an aerated bottom drain?

No. This model is a weighted suction drain and does not include an air diffuser. See our Retro Fit Bottom Drain With Aerator if you need a freestanding drain with aeration.

Can it connect directly to a gravity-fed drum filter?

Not as a conventional 110 mm gravity drain. This model uses a 1.5 inch pump-fed suction connection.

Are the pump and hose included?

No. The pump, hose, clips and installation-specific fittings are selected separately to match the pond.