Seachem Stability
Water type
Freshwater + Marine
Seachem Stability
Establishes a safe, functioning biofilter in days, not weeks. Seachem Stability seeds new freshwater and marine aquariums with a blend of nitrifying bacteria that breaks down waste organics, ammonia, nitrite and nitrate, helping prevent new-tank syndrome. It also works as an ongoing maintenance dose after water changes, new fish introductions, or medication use.
Nano and starter tanks up to around 200 L suit the 50 mL or 100 mL bottles for a single new-tank cycle. Hobbyists running a full water-change routine or several tanks get better value from the 500 mL to 2 L range, while multi-tank retailers and large systems suit the 4 L or 20 L packs.
Key features
- Broad-spectrum bacterial blend — aerobic, anaerobic and facultative strains break down waste organics, ammonia, nitrite and nitrate together.
- No hydrogen-sulfide risk — the strains are non-sulfur-reducing, so they will not produce toxic hydrogen sulphide the way some competing bacterial products can.
- Tolerant of temperature and pH swings — remains effective across the range of conditions found in a typical new set-up, rather than needing a narrow band.
- Shelf-stable spore form — bacteria are supplied as dormant spores that withstand extreme temperatures and need no food until diluted in tank water, so no refrigeration is required.
- Harmless to fish, invertebrates and plants — safe to dose at the recommended rate with no risk of overdosing livestock or plants.
- One product for freshwater and marine — a single bacterial starter covers both set-up types.
- Cost per litre falls as pack size rises — the 20 L pack works out the cheapest per litre of tank water dosed of the range (see table below).
Specifications
| Attribute | Detail |
|---|---|
| Form | Liquid suspension of dormant bacterial spores |
| Water type | Freshwater and marine (saltwater) aquariums |
| Storage | Shelf-stable; does not require refrigeration |
| Bacteria type | Aerobic, anaerobic and facultative, non-sulfur-reducing strains |
Dosage and directions
Shake well before use. Seachem's official new-tank schedule is:
- Day 1: 5 mL (1 capful) per 40 L of tank water.
- Days 2-7: 5 mL (1 capful) per 80 L of tank water, once daily.
Fish may be introduced immediately provided the 7-day schedule is followed. For ongoing maintenance, dose 5 mL per 80 L once a month, or with every water change, whenever new fish are introduced, or whenever medicating the aquarium.
Cost per litre of tank water dosed
Working from Seachem's maintenance rate of 5 mL per 80 L: divide each bottle's volume by 5 mL to get the number of maintenance doses per pack, then multiply by 80 L to get the total litres of tank water that pack can maintenance-dose over its life. Retail price divided by that litres figure gives the cost per litre below.
| Size | Maintenance doses per pack | Litres of tank water maintained per pack | Cost per litre |
|---|---|---|---|
| 50 mL | 10 | 800 L | 1.6c per litre |
| 100 mL | 20 | 1,600 L | 1.1c per litre |
| 250 mL | 50 | 4,000 L | under 1c per litre |
| 500 mL | 100 | 8,000 L | under 1c per litre |
| 1 L | 200 | 16,000 L | under 1c per litre |
| 2 L | 400 | 32,000 L | under 1c per litre |
| 4 L | 800 | 64,000 L | under 1c per litre |
| 20 L | 4,000 | 320,000 L | under 1c per litre |
Suitable for
- New freshwater and marine set-ups being cycled before livestock is added.
- Established tanks after water changes, new fish introductions, or medication treatment.
- Retailers and hobbyists wanting one bacterial starter that covers both freshwater and marine systems.
Not suitable for
- Replacing a fishless cycle check — always confirm ammonia and nitrite have dropped to zero with a test kit before treating the tank as fully cycled.
- Dosing at the same time as active UV sterilisation or ozone treatment (see safety notes).
Safety notes
Switch off UV sterilisers and ozone generators while dosing, as both will kill the beneficial bacteria before they can colonise the filter. Shake the bottle well before each use.
Warranty and delivery
Covered by Seachem's manufacturer support in addition to the guarantees you're entitled to under Australian Consumer Law.
Common questions
Can I add fish immediately after dosing?
Yes. Seachem's instructions confirm fish can be introduced immediately provided the 7-day new-tank dosing schedule is followed as directed.
Why isn't my tank cycling instantly?
Stability seeds the filter with bacteria, but those bacteria still need to multiply to match the tank's waste load. Continue the 7-day dosing schedule and monitor ammonia and nitrite with a test kit rather than judging by dosing alone.
Does it work in a marine tank?
Yes, the bacterial blend is formulated for both freshwater and marine aquarium systems.
Do I need to refrigerate the bottle?
No. The bacteria are supplied as dormant spores that tolerate a wide temperature range and only activate once diluted in tank water, so the bottle stores at normal room temperature.
How often should I dose after the tank has cycled?
Seachem's maintenance rate is 5 mL per 80 L of tank water, applied monthly or with every water change, new fish introduction, or medication treatment.
Will it overdose my fish or plants?
Seachem states the product is harmless to fish, invertebrates and plants at the recommended dosing rate, so there is no risk from following label directions.
