API Quick Start vs Seachem Stability: Do Bottled Bacteria Help?
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Bottled bacteria are sold as a way to jump-start a new tank, and the claims on the bottle can sound like a shortcut. Here's what the listings say, and what extension research says about cycling. We haven't tested them.
Side by side
| API Quick Start | Seachem Stability | |
|---|---|---|
| What it is | Nitrifying bacteria (listing) | Blend of aerobic, anaerobic and facultative bacteria (listing) |
| When to use | New tank, new fish, media changes | New tank: day 1, then daily for 7 days |
| Dose | See bottle | 5 mL per 10 gal on day 1; then 5 mL per 20 gal daily |
| Maker claim | "Allows instant addition of fish" | Prevents "new tank syndrome" |
| Fresh or salt | Both | Both |
What the research says
- Time: UF says a new biofilter "requires six to eight weeks to build up sufficient bacteria." Another UF fact sheet says "three to eight weeks, or longer."
- Cultures can help: that UF fact sheet lists "using active commercially available biofilter bacterial cultures from reputable sources" as a cycling option, alongside dosing ammonia and using media from an established system.
- Stock slowly: Aqueon warns that "adding too many fish at once or overfeeding a new freshwater aquarium" causes "New Tank Syndrome."
So treat these as help, not a skip button. Test daily during the first weeks; UF says to measure ammonia and nitrite "to determine when the ammonia and nitrite levels have peaked and then dropped."
The picks
API Quick Start (4 oz)
- Nitrifying bacteria for fresh or saltwater, per the listing
- Use when starting a tank, adding fish or changing media
Seachem Stability (250 mL)
- Bacteria blend to establish the biofilter, per the listing
- Day 1: 5 mL per 10 gallons; then 5 mL per 20 gallons daily for 7 days (listing)
- Turn off UV or ozone while dosing
API Freshwater Master Test Kit
- Tests pH, high-range pH, ammonia, nitrite and nitrate, per the listing
- 7 test solutions, color card and 4 tubes
- Listed as 800 tests; freshwater only
Full walkthrough: how to cycle a fish tank.
FAQ
Instant cycle?
API's listing says so; UF describes weeks. Test to confirm.
Stability dosing?
Day 1 heavier, then daily for 7 days.
Quick Start timing?
New tank, new fish, water or media changes.