Hydroponic Air Pumps

Why roots need dissolved oxygen

Roots take up oxygen from the water around them, and when that oxygen runs out the root zone goes anaerobic — which is where root rot starts and where nutrient uptake stalls. Warm solution holds less oxygen than cool solution, so the problem shows up fastest in summer and in large, still reservoirs.

An air pump fixes this mechanically. It pushes air down a length of tubing to a stone on the bottom of the tank; the stone breaks that air into fine bubbles, and the bubbles both carry oxygen into the solution and stir the tank as they rise. Aqua One note their stones are excellent for getting air to roots in hydroponic systems.

An air pump is not a water pump

This is the most common mix-up in the category, and the two are not interchangeable. An air pump moves air, is rated in litres of air per hour or per minute, and sits outside and above the reservoir. A water pump moves liquid, is rated in litres per hour plus a head height, and sits in the tank. A drip system needs a water pump; a deep water culture tank needs an air pump. The water pumps page covers the other half.

Our range of hydroponic air pumps

Diaphragm pumps and complete kits

Aqua One's Precision series runs from 160L/hr on the 2500 up to 1900L/hr on the Precision 12000, which has four outlets, speed control and draws 9.4W. The Infinity range is sold ready to run: the AP750 is a twin-outlet 2 x 200L/hr unit at 4W with a flow adjustment switch, and every Infinity ships with air hose, a check valve and air stones. PondMAX's CT402 is the same idea — two outlets at 2.8 litres per minute each from 5W, supplied with 2m of silicone airline, two ceramic air stones and two check valves.

Piston and electromagnetic pumps

Sensen's ACO series drives a reciprocating piston from a permanent-magnet motor rather than a diaphragm. Sensen state the non-oil design produces cleaner compressed air than diaphragm pumps and that the aluminium housing disperses heat for a longer life. The 20W and 45W models are stocked.

Pond aerators

OASE and PondMAX also supply aerators built for ponds, and they do the same job in a reservoir. The OxyMax 200 is a 3.5W unit rated 200L/hr with 4mm inner-diameter hose connections and an IPX4 rating; the Pond-One O2 Plus range reaches 6600L/hr. Check outlet count and airline diameter against what you already run.

How to choose an air pump

1. Count your outlets first. One outlet feeds one stone, so four deep water culture buckets means four outlets or a manifold. The Precision 12000 gives four; the twin Infinity and PondMAX units give two.
2. Then match output to reservoir volume. More water needs more air, and a warm tank needs more again. Undersizing shows quickly: the surface stops moving.
3. Check pressure if the tank is deep. Air must be pushed down against the water above the stone, so a pump that is fine on a shallow tray can struggle in a tall reservoir. PondMAX quote 0.02MPa on the CT402 — the higher that figure, the deeper the stone can sit.
4. Think about noise. These run around the clock, so a rattly pump becomes a daily problem. Placement does as much as the spec sheet: sit the unit on foam rather than a hard shelf and keep it off the tent frame.
5. Fit a check valve. The airline runs downhill into the tank, so a power cut siphons water back up the line and into the pump. A one-way check valve stops it. Several kits include one.

Setting one up

Keep the pump above the water line, always, with the check valve in the line between pump and stone. Give it a flat, stable surface — Aqua One fit rubber feet for the same reason. Aqua One also recommend replacing air hose and stones annually to stop clogging and algae build-up.

Air pumps pair with the deep water culture systems and with a reservoir from the tanks and reservoirs range. If you need solution delivered to each pot instead, that is the irrigation page.