An air stone turns a stream of air into a curtain of fine bubbles — boosting oxygen, driving sponge filters, and helping fish through summer heatwaves when warm water holds less oxygen. Paired with an air pump, it is cheap, useful kit. This UK guide covers the best air stones in 2026.

Here are our picks and how to use them.

When you need one

• Summer heat — warm water holds less oxygen; extra aeration helps.
• Sponge filters — an air stone or the pump drives the flow.
• Heavily stocked or breeding tanks that need more oxygen.
• Medication — many treatments reduce oxygen, so extra aeration is wise.

Our top picks

Best fine bubbles — air stone disc. A air stone disc produces a fine, even curtain of bubbles for maximum oxygen transfer.

Best for sponge filters — cylinder air stone. A cylinder air stone fits neatly under a sponge filter.

Complete the setup. Add an air pump, some airline tubing and a non-return valve.

Setup tips

Always fit a non-return (check) valve in the airline between pump and stone — without one, a power cut can siphon tank water back into the pump. Soak a new air stone in water before first use to clear it. Air stones clog over time; replace them when the bubbles weaken. See our air pump guide for sizing.

Frequently asked questions

Do I need an air stone in my aquarium?

Not always, but they help in summer heat, in heavily stocked or breeding tanks, when medicating, and to drive sponge filters. Warm water holds less oxygen, so extra aeration is useful in a UK heatwave.

How do I set up an aquarium air stone?

Connect it to an air pump with airline tubing, and always fit a non-return valve between the pump and stone so a power cut can't siphon water back into the pump. Soak a new stone before first use.

Why has my air stone stopped bubbling well?

Air stones clog with mineral deposits and debris over time. When the bubbles weaken, clean or simply replace the stone — they are inexpensive consumables.

---

— Jaqline Smalling, FishForever