Phytoplankton for Corals: How Much to Dose

Erik Stenn

Phytoplankton is the foundation of the marine food web. In a reef aquarium, dosing live phytoplankton provides essential fatty acids, proteins, and vitamins to corals, clams, and other filter feeders. However, the most common question reefers ask is: "How much should I actually dose?"

Because every reef tank has a different biological load and filtration capacity, there is no "one size fits all" answer. Instead, successful dosing is about finding the balance between providing enough nutrition and maintaining pristine water quality.

    In one sentence: Start with a conservative dose and gradually increase it while monitoring your tank's nutrient levels (Nitrate and Phosphate).
  

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General Dosing Guidelines

For most high-density live phytoplankton products like PhycoPure™, a standard starting point is 1-2 teaspoons (5-10ml) per 50 gallons of tank water, 2 to 3 times per week.

Factors that influence your dose:

Coral Type: SPS corals and clams generally require more frequent, smaller doses than large-polyp stony (LPS) corals.
Filtration: If you run a heavy protein skimmer or UV sterilizer, much of the phytoplankton may be removed before corals can consume it.
Biodiversity: Tanks with large populations of copepods and rotifers will consume phytoplankton much faster.

Dosing Chart by Tank Type

Tank Focus	Recommended Frequency	Suggested Dose (per 50 gal)	Goal
Mixed Reef	3x per week	5ml - 10ml	General health and biodiversity
SPS Dominant	Daily (Small amounts)	2ml - 5ml	Consistent energy for small polyps
Clam / Gorgonian Tank	Daily	10ml+	High-volume filter feeding support
New Tank (Cycling)	1x per week	2ml - 5ml	Seeding microfauna without spikes

Best Practices for Dosing

Turn off the Skimmer: Turn off your protein skimmer and mechanical filtration for 30-60 minutes after dosing to allow the corals time to feed.
Target Feeding: For specific corals like Gorgonians or sun corals, use a pipette to gently puff a small cloud of phytoplankton directly over the polyps.
Night Dosing: Many corals extend their feeding tentacles at night. Dosing after the lights go out can often yield better results.
Keep it Fresh: Live phytoplankton is a living product. Always check the "best by" date and keep it refrigerated to maintain nutritional value.

Signs of Overfeeding

If you notice a sudden spike in Nitrates or Phosphates, or if you see an increase in nuisance film algae on the glass, you may be dosing more than your system can process. Simply reduce the frequency or amount until levels stabilize.

    Takeaway: Phytoplankton is a powerful tool for reef health. Start slow, observe your corals' response, and adjust your dose to match your tank's unique needs.
  