Kockney Koi Yamitsu 4mm Airline – Black or Clear 30m Roll

Kockney Koi Yamitsu 4mm Airline – Black or Clear 30m Roll

A complete roll of small-bore airline is useful when you are arranging several air stones, replacing old tubing or extending a compatible aeration system. Kockney Koi Yamitsu heavy-duty 4mm airline is supplied here in a 30m roll, with a choice of black or clear tube. Both options have a 4mm internal diameter and a 6mm outside diameter. Select the colour you need; the length and connection dimensions are the same.

This is conventional, non-weighted airline. It is not sold as sinking hose, and the roll does not include an air pump, manifold, connectors or diffusers. The 30m length describes how much tubing you receive, rather than a recommendation to run an individual air stone 30m from its pump. Plan each branch around the equipment and its operating instructions.

Black or clear: choosing the right option

Option	Roll length	Bore	Outside diameter
Black	30m	4mm	6mm
Clear	30m	4mm	6mm

Black tubing can make an exposed route less noticeable against dark equipment or the pond surround. Clear tubing lets you see inside the line when checking its condition. Colour does not determine the air pump capacity or make a hose self-sinking. Choose on the basis of the required connection size and route first, then the appearance that works best for your installation.

The heavy-duty description identifies this Yamitsu product range. It is not a stated industrial working-pressure rating, and this listing should not be used to select tubing for compressed-air machinery, oxygen cylinders or other applications outside ordinary compatible pond and aquarium air equipment.

Match the airline to the fittings

Read the connection details on your equipment before ordering. The inside of this tube is 4mm across; the outside is 6mm. A hose barb intended for 4mm-bore airline and a connector specified for 6mm outside-diameter tube are different connection designs, even though the same two numbers appear in their descriptions. A similar-looking fitting is not enough to establish a suitable connection.

Our Kockney Koi 4mm airline connectors provide several shapes for compatible small-bore branches. A straight connector joins lengths; an elbow changes direction; a tee divides a line. Where branches need different airflow, use a suitable regulating valve rather than expecting a plain tee to balance the system automatically.

Do not reduce a large pump’s main outlet to this bore unless the pump instructions specify that arrangement. Larger pond air pumps often use a larger main line and a distribution manifold. Small branches should be connected at the appropriate point in that system, with sufficient outlets left available for the pump to operate correctly.

Measure and route the tubing

Measure from the connection point to the final air-stone position, including the vertical drop into the water and any bends around the pond edge. Allow enough slack to remove the diffuser for cleaning without pulling on its connector. If several runs are needed, make a simple list of their lengths before cutting the roll so that useful continuous sections are not wasted.

Keep bends broad and avoid sharp folds. A flattened section restricts airflow even when the rest of the tube looks clear. Do not trap the line under a filter lid, heavy rock or paving slab. Where it crosses a sharp edge, arrange suitable protection and support without tightening a fixing so much that it compresses the bore.

Cut the tube cleanly and squarely with a suitable sharp tool, keeping your hands clear. Connect it according to the equipment instructions and check that it cannot easily pull free. If reusing an old length, inspect the end for splitting or permanent stretching. Trimming damaged material can help only if enough sound tubing remains and the finished line still reaches comfortably.

Prevent backflow and check operation

Follow the air pump’s instructions for its position relative to water level and any non-return valve required. Fit a valve in its marked direction and include it in routine maintenance checks. Water travelling back along an airline can reach the pump when power is interrupted, so a neat-looking route must still follow the equipment’s installation requirements.

Once the connections are complete, run the system and check each diffuser. Uneven bubbling may be caused by different water depths, unequal hose runs, valve settings, leaks or dirty air stones. Work through these possibilities before assuming the pump needs replacing. Avoid shutting every outlet while the pump is running; follow its guidance on minimum airflow and pressure relief.

Alternatives for the pond floor

If you want the hose to sit along the bottom of the pond, compare our standard sinking airline and Evolution Aqua heavy-duty sinking airline. Check both bore and fittings when changing products. Weighted hose is selected for its ability to sink, not simply because it is black.

For suitable larger connections, black braided airline offers a reinforced alternative. That product does not sink either. Keep unused tubing clean and loosely coiled, and inspect installed airline whenever you service the pump, valves or air stones.