Kockney Koi 4 Inch Flat Air Stone

Kockney Koi 4 Inch Flat Air Stone

A compact disc diffuser with connections for 4mm and 8mm airline

The Kockney Koi 4 Inch Flat Air Stone is a compact diffuser for introducing air from a suitable air pump into pond water. Its flat, round shape gives you an alternative to a ball or cylinder air stone, particularly where you want a low-profile diffuser rather than a tall component. Kockney Koi confirms that this model accepts both 4mm and 8mm airline and fittings, making it useful when replacing a diffuser on an existing small-bore air supply.

This listing is for the 4 inch model, manufacturer reference 001879. Choose it by its size and connection requirements as well as by appearance: a larger air disc is not automatically a suitable replacement for a smaller one on the same pump. The pump must deliver enough air against the resistance of the complete installation, including the diffuser, hose length and depth of water.

Product details at a glance

Product	Kockney Koi Flat Disk Air Stone
Nominal size	4 inch
Shape	Flat round disc
Compatible airline sizes	4mm and 8mm
Manufacturer reference	001879
Barcode	5031589001879
Quantity	One air stone
Air supply	Suitable air pump required separately

Choosing your airline

Check the internal diameter of your airline before ordering fittings. Airline sizes refer to the bore that fits over the connector; measuring only the outside of a thick-walled hose can lead to choosing the wrong connection. The manufacturer’s stated 4mm and 8mm compatibility gives you two options, but the rest of the air circuit must also match. A pump outlet, manifold, connector and diffuser do not necessarily all use the same hose size.

For pond installations where you want the hose to lie below the surface, see our standard sinking airline and Evolution Aqua heavy-duty sinking airline. Select a compatible bore from the available options. Black braided airline can also carry the air where its bore fits, but it does not sink by itself. Choose sinking hose when that property matters to the appearance and routing of your installation.

Connecting the stone to an air supply

Plan the route from the air pump to the diffuser before cutting the hose. Avoid sharp bends, stretched connections and positions where the hose will be trapped beneath a lid or paving slab. Leave enough accessible hose to lift the diffuser out for inspection without pulling against its inlet. Support the air stone itself when moving it rather than lifting it by the hose connection.

If you are extending or splitting an 8mm supply, our Kockney Koi 8mm airline connectors provide matching connector options. Adding a branch divides the pump’s available air; it does not increase its capacity. Where several diffusers share one pump, check the operation of every branch after making a change, since the easiest route can take more air than the others.

Positioning and commissioning

Place the disc where its aeration serves the area you intend to support and where it remains accessible for maintenance. Keep its working surface clear of accumulated debris. A diffuser buried in sediment cannot perform as intended, and disturbing a heavily silted pond bottom simply to reposition it can release a considerable amount of dirt into the water. Use a clean, suitable resting position and inspect the result once the air is running.

Follow your pump manufacturer’s installation instructions, including its requirements for protection from weather and prevention of water reaching the pump when switched off. A diffuser is not a non-return valve. If your installation requires an anti-syphon valve, use a separate compatible component and fit it in the correct direction. Keep electrical equipment and connections in their intended protected locations.

Checking performance and maintaining airflow

Watch the diffuser after installation and again after the system has been running for a while. Changes in bubble output can come from several places: a kinked hose, a loose joint, restricted fittings, a dirty diffuser or a pump requiring attention. Check the air path methodically before replacing components. Comparing branches on the same pump can help you identify whether a problem is local to one line.

Inspect the stone and its inlet during routine pond maintenance. Remove loose surface debris gently and follow the product’s care instructions for cleaning. Avoid poking through the diffuser surface or using a cleaning chemical simply because it works on other pond equipment. Replace the stone if it becomes damaged or remains badly restricted after appropriate maintenance. A clean connection and an unobstructed hose are just as important as a clean diffuser.

Is this the right diffuser for your pond?

This is a useful choice when you specifically need the compact 4 inch Kockney Koi disc and a compatible 4mm or 8mm connection. For other diameters, compare our ceramic flat air discs. Choose the diffuser alongside the pump’s performance at your installation depth; an air stone’s diameter alone does not establish a pond-volume rating or the number of fish a system can support.

When planning a new arrangement, have the pump model, intended diffuser depth, hose length and number of air outlets to hand. Those details are more useful for checking compatibility than the pump’s headline maximum airflow alone. This air stone supplies the diffuser component; allow separately for the pump, airline and any fittings your particular layout requires.