Choose options
Hakko linear diaphragm air pumps — the quiet, oil-free standard for koi pond aeration
Hakko pumps use a magnet-driven diaphragm instead of a piston: no oil, no wear parts touching, 32–56 dB of noise and a diaphragm you can replace yourself in ten minutes. Eleven sizes from 37 to 378 LPM cover a 1,000-gal patio pond to a 24,000-gal koi lake.
Image coming soon
Mystic Koi’s take
Buy one size bigger than the chart says and run it with a manifold — you will add diffusers later, and a pump loafing at 70% lasts far longer than one maxed out. Mount it at least 2" above water level (a stand or wall bracket); a flooded pump is not covered by warranty. For diffusers deeper than ~8 ft, step up to the MPC compressor.
What it does
- Oil-free linear driveNo piston, no oil, no contamination.
- QuietAs low as 32 dB on the 25L.
- Overload protectionThermal cut-out on every model.
- Field-rebuildableDiaphragms, magnets, filter pads and stands stocked.
- LP modelsLow-profile 25LP / 40LP for tight spaces.
- Energy-efficientHK-60L moves 94 LPM on 61 W.
Hakko specifications (115 V / 60 Hz, per Matala)
| Model | Max flow | Rated flow | Power | Noise | Suggested pond |
|---|---|---|---|---|---|
| HK-25L | 37 LPM (1.3 CFM) | 26 LPM | 24 W | 32 dB | 1,000–2,500 gal |
| HK-25LP | 37 LPM | 26 LPM | 24 W | 36 dB | 1,000–2,500 gal |
| HK-40L | 70 LPM (2.5 CFM) | 45 LPM | 38 W | 39 dB | 2,000–4,000 gal |
| HK-40LP | 70 LPM | 45 LPM | 38 W | 35 dB | 2,000–4,000 gal |
| HK-60L | 94 LPM (3.3 CFM) | 65 LPM | 61 W | 38 dB | 3,000–6,000 gal |
| HK-80LH | 119 LPM (4.2 CFM) | 80 LPM | 82 W | 38 dB | 4,000–8,000 gal |
| HK-100L | 129 LPM (4.6 CFM) | 102 LPM | 110 W | 40 dB | 5,000–10,000 gal |
| HK-120LH | 172 LPM (6.1 CFM) | 120 LPM | 130 W | 42 dB | 6,000–12,000 gal |
| HK-150L | 238 LPM (8.4 CFM) | 150 LPM | 145 W | 52 dB | 8,000–16,000 gal |
| HK-200L | 284 LPM (10 CFM) | 200 LPM | 160 W | 54 dB | 10,000–20,000 gal |
| HK-250L | 378 LPM (13.4 CFM) | 250 LPM | 227 W | 56 dB | 12,000–24,000 gal |
Rated pressure 1.42–2.85 psi across the line (roughly 3–6.5 ft of water depth at rated flow).
Pairs well with
The science: why bottom aeration matters more than a waterfall
Oxygen enters water at the surface, and a diffuser’s rising bubble plume lifts bottom water up to the surface in a continuous loop. That circulation is the real work: it de-stratifies the pond, keeps the bottom from going anoxic, and carries ammonia to the filter. Fine bubbles transfer more oxygen per cubic foot of air because of their larger total surface area and slower rise. Warm water holds less oxygen (about 7.6 mg/L at 86 °F vs 11.3 mg/L at 50 °F), which is why summer nights are when koi gasp.
- Matala Water Technology Co. (2026). Aeration product data — Hakko linear pumps, MDB platforms, membrane diffusers, Ez-Air Pro kits. matala.com.tw.
- Boyd, C.E. (1998). Pond water aeration systems. Aquacultural Engineering 18(1): 9–40.
- USGS (2024). Dissolved oxygen solubility tables (fresh water, sea-level).
Questions we get about the Hakko
L vs LP vs LH?
L is the standard case; LP is the low-profile body (25/40 only); LH is a higher-pressure version of the same airflow class (80, 120) for deeper diffusers.
How deep can it push?
Comfortably to about 6–8 ft of water with Matala low-back-pressure diffusers. Beyond that use the MPC rocking-piston compressor.
How often do I rebuild it?
Diaphragms typically last 2–3 years of continuous running; the kit takes ten minutes with a screwdriver.
Matala at Mystic Koi
Matala filter media and pond equipment have been a koi-keeping staple for decades, and Mystic Koi has sold and run Matala gear in our own systems since we opened in Upland, California in 1996. Everything on this page ships from Matala USA (Sea Life Designs) or our ¾-acre facility. Not sure what fits your pond? Call or visit and we’ll size it with you.