Unplug the pump, take it apart, and soak it in citric acid: Bulk Reef Supply uses 1 cup of dry citric acid per US gallon of RODI water, about 60 g per litre. Soak for 30–60 minutes for light build-up, longer for heavy, then scrub, rinse well in RODI water and refit. Never add citric acid to the tank.
Why pumps need cleaning
Calcium carbonate and coralline algae build up on impellers, magnets and housings. The pump gets louder and moves less water, and can eventually seize. A soak dissolves the deposits that brushing can’t reach.
The mix
Bulk Reef Supply’s recipe is 1 cup of dry citric acid per US gallon (3.8 L) of RODI water, which it gives as about 6%, or roughly 60 g per litre. Food-grade citric acid is sold in the UK for cleaning and home brewing.
| Build-up | Soak |
|---|---|
| Light | 30–60 minutes |
| Moderate | 1–3 hours |
| Heavy | 3–6 hours |
| Second round after scrubbing | 15–20 minutes |
Times from Bulk Reef Supply. It says plastic, ceramic, corrosion-resistant metal and rubber parts are generally safe for up to 24 hours.
Step by step
Follow your pump maker’s instructions on taking it apart.
- Unplug the pump before removing it; running it dry can damage it
- Take it apart: housing, impeller, shaft, cage
- Soak the parts, or soak the whole pump running in the solution if it’s safe to do so
- Scrub with an old toothbrush; soak again briefly if needed
- Rinse everything thoroughly in RODI water before refitting
How often
Bulk Reef Supply suggests a quick clean of visible wavemakers and return nozzles about once a month, and a full strip-down once or twice a year. Many keepers soak return pumps and wavemakers every three months.
Citric acid is generally preferred to vinegar, Bulk Reef Supply says, because vinegar may be harder on magnets, seals and gaskets over time. Never put citric acid in the tank, and don’t soak live rock.
Common questions
Can I use vinegar instead?
You can, but Bulk Reef Supply says citric acid is generally preferred for routine use.
How long should I soak a pump?
30–60 minutes for light build-up, up to 3–6 hours for heavy.
Is citric acid safe for my tank?
Not in it. Rinse every part thoroughly in RODI water before refitting.
Sources and limits
Last checked 13 October 2026. Follow your equipment maker’s own instructions where they differ from this guide.
Keep going
Add a pump clean to your routine · Free Reef Companion · All calculators