Methods
Carbon dosing in a reef tank: vodka, vinegar and more
Feed bacteria a carbon source so they multiply, take up nitrate and phosphate, and get skimmed out. It works, and it is easy to overdo.
Last checked . How we check
- Cost
- Low
- Effort
- Medium (frequent tests)
- Suits
- Established tanks with stubborn high nitrate
- Needs
- A good skimmer and regular tests
How does it work?
Bacteria need carbon, nitrogen and phosphorus to grow. Adding carbon lets them use up more nitrate and phosphate, and the skimmer removes the bacteria. Red Sea's NO3:PO4-X is a branded carbon mix; Red Sea's own comparison says vodka lowers nitrate but not phosphate and can skew the ratio.
How do people start vodka dosing?
A widely shared hobby schedule (typical, check) is 0.1 ml of 40% vodka per 100 litres of net volume a day for three days, double that for days four to seven, then raise by 0.5 ml a week until nutrients fall, then hold. Underestimate the volume rather than over. A skimmer is widely advised; we found no source that proves it essential.
What can go wrong?
Keepers report cyanobacteria, alkalinity drops, cloudy bacterial blooms and low oxygen. Stop at once if nutrients fall to zero, as dinoflagellates follow.
How do I get started?
- Test nitrate and phosphate for two weeks to know your starting point.
- Start at the lowest dose on a reduced volume.
- Test both twice a week.
- Raise slowly; stop raising when nitrate starts to fall.
- Never let either reach zero.
What are the common mistakes?
- Starting on a new tank.
- Raising the dose before the last one shows.
- Running without a skimmer on a heavy dose.
- Taking nutrients to zero.
Where do sources disagree?
| Topic | What sources say | Our reading |
|---|---|---|
| Is a skimmer required? |
| Use a skimmer. |
Sources
Figures from sources read as a search summary only are shown as typical figures: check them before you rely on them. Found a mistake? Tell us how to fix it.