Seachem Phytoplankton
Pack size
250 mL
Cost per litre
Under 1c
Water type
Marine
Protein / fat
0.4% / 0.15%
Pack size
500 mL
Cost per litre
Under 1c
Water type
Marine
Protein / fat
0.4% / 0.15%
Seachem Phytoplankton
A blanket-feed phytoplankton blend sized for filter feeders, not just fish. Seachem Reef Phytoplankton is a concentrated mix of marine microalgae – Thalassiosira weissflogii, Isochrysis sp. and Nannochloropsis – with cell sizes from 1 to 20 microns, spanning the range corals, clams and other filter feeders can actually capture.
It's dosed into the water column rather than spot-fed to an individual coral, so every filter feeder in the tank gets a pass at it. Shake well before use, and dose with pumps off briefly so the plankton has time to settle within reach before flow scatters it.
Key features
- Three-species blend – Thalassiosira weissflogii, Isochrysis sp. and Nannochloropsis, covering a 1–20 micron size range.
- Blanket feed, not target feed – designed to be dosed into the water column for every filter feeder to draw on, not squirted at one coral.
- Astaxanthin included – a natural carotenoid included to support colour and act as an antioxidant.
- Simple dosing – the bottle cap measures 5 mL, matched to the standard dose.
- Two pack sizes – 250 mL and 500 mL, both dosed the same way.
Specifications
| Form | Liquid concentrate, shake before use |
|---|---|
| Species | Thalassiosira weissflogii, Isochrysis sp., Nannochloropsis |
| Particle size | 1–20 microns |
| Dose | 5 mL per 190 L, twice weekly or as required |
| Water type | Saltwater (reef) |
| Storage | Refrigeration after opening recommended, not required |
Ingredients
Concentrated blend of green and brown marine phytoplankton (Thalassiosira weissflogii, Isochrysis sp., Nannochloropsis), sodium chloride, acetic acid, ascorbic acid, citric acid, astaxanthin.
Guaranteed analysis
| Component | Guarantee |
|---|---|
| Crude protein | Minimum 0.40% |
| Crude fat | Minimum 0.15% |
| Moisture | Maximum 96.8% |
Suitable for, and not suitable for
- Suitable for: a broad range of tropical marine filter feeders and invertebrates – corals, clams, feather dusters and similar planktivores.
- Not suitable for: target-feeding a single coral head – Seachem's own directions call for blanket feeding into the water column, not spot dosing.
Dosage and directions
- Shake well before using.
- Dose 5 mL (one capful) per 190 L of tank water, twice weekly, or more often if your filter feeders are drawing it down quickly.
- For blanket feeding, dose into an area of flow so it disperses through the tank rather than settling in one spot.
- Refrigerate after opening if convenient – not essential, but it helps the concentrate keep.
Care and maintenance
Watch water clarity and skimmer output after dosing – a heavy hand with any planktonic food can cloud the water or overload a skimmer. Start at the label rate and adjust from there based on how quickly your filter feeders visibly respond.
Goes well with
- Seachem Zooplankton – a complementary feed for filter feeders that take a larger particle size.
- A protein skimmer rated for your tank volume – to keep pace with the extra organic load from regular plankton dosing.
- Coral and clam supplements – plankton feeding supports growth alongside, not instead of, stable calcium and alkalinity.
Warranty and delivery
Covered by Seachem's standard quality guarantee in addition to your rights under Australian Consumer Law. Standard shipping; no cold chain required, though refrigeration after opening is recommended.
Common questions
Can I target-feed a specific coral with this?
Seachem's own directions call for blanket feeding into the water column rather than spot-dosing one coral – it's formulated for every filter feeder in the tank to draw on.
How often should I dose Reef Phytoplankton?
Twice weekly at 5 mL per 190 L is the standard rate; increase frequency if your filter feeders are clearly consuming it and water quality allows.
Will this cloud my water?
Dosed at the label rate it shouldn't cause lasting cloudiness, but overdosing can cloud the water and stress your skimmer – start at the standard dose and watch clarity.
Does it need refrigeration?
Recommended after opening, but not required – a cool, dark cupboard is fine if fridge space is tight.
What's in it besides phytoplankton?
Sodium chloride, acetic acid, ascorbic acid and citric acid as preservatives and stabilisers, plus astaxanthin, a natural carotenoid included for colour and antioxidant support.
