• Fine-bubble diffusion — a finer bubble column drives more surface movement per litre of air than a bare airline end.
• 2.5 cm size — small enough to hide behind a rock or plant, or to drop into a quarantine tub.
• Push-fit to standard airline — no adaptor, no clamp, no tools.
• Freshwater and marine — the same stone works in either, though salt shortens its service life.

Marina does not currently publish a material composition, a recommended pump output range or a service life for this stone, so none is stated here.

Included

• One 2.5 cm air stone on a card

Not included

• An air pump — the stone does nothing on its own. For power cuts and transport, see the Marina Battery Operated Air Pump
• Airline tubing
• A check valve, which stops water siphoning back into the pump if the pump sits below the water line

Suitable for

• Adding surface movement and gas exchange to a community or marine tank
• Aerating a quarantine tub, hospital tank or fry container
• Driving a sponge filter or an under-gravel uplift

Not suitable for

• Diffusing CO2 — air stones are far too coarse for that, and running CO2 alongside heavy aeration works against you
• Tanks holding fish that dislike current and surface turbulence, such as bettas, unless the pump output is turned right down
• Use without a check valve where the pump sits below the water line

Air stones are consumables. Over weeks to months the pores fill with mineral scale and biofilm, the bubbles coarsen and the pump has to work harder against the back pressure.

Soak a clogged stone in fresh water and scrub it lightly, or replace it. Do not use soap or detergent. Replace the stone once cleaning no longer restores a fine, even bubble column.

• Marina Battery Operated Air Pump — the air source for transport tubs and blackouts
• Marina Fish Net Breeder Box — pairs with a stone to keep water moving around fry
• Marina Black Fish Net — for moving fish into the aerated container
• Marina Floating Glass Thermometer — aeration cools a small container faster than people expect

Air stones are a consumable item and carry no published manufacturer warranty term. Your rights under the Australian Consumer Law apply in addition to anything the manufacturer offers, and are not limited by this page.

Ships as a standard parcel item. No dangerous goods or oversize handling applies.

Do bubbles actually add oxygen to the water?

Mostly indirectly. Very little oxygen transfers from inside a rising bubble. The gain comes from the bubbles breaking the surface and constantly renewing the water in contact with air, which is why a stone placed low in the tank does more than one sitting near the top.

How often should an air stone be replaced?

When the bubble column coarsens or the pump starts labouring. There is no fixed interval, and hard water and marine tanks clog a stone faster than soft fresh water.

Do I need a check valve?

If the air pump sits below the water level of the tank, yes. Without one, a power cut can siphon tank water back down the airline and into the pump.

Will one 2.5 cm stone be enough for my tank?

For a small tank or a quarantine tub, usually. Aeration is set by the pump's output and the number of outlets rather than by stone size, so on a larger tank people generally run two stones or a longer bubble bar.