Seachem Reef Phosphorus 250 mL – Reef Aquarium Phosphate Supplement
Seachem Reef Phosphorus 250 mL is a concentrated phosphorus supplement formulated for marine and reef aquariums with low phosphate levels. Phosphorus is an essential nutrient involved in coral and macroalgae metabolism, protein synthesis, growth, and coloration.
Reef Phosphorus provides a controlled way to increase phosphate without adding dissolved organic material. It is especially useful in low-nutrient reef aquariums where phosphate is consistently below the desired range despite regular feeding.
Key Features
- Targeted Phosphate Supplement: Provides a controlled source of phosphorus for marine and reef aquariums
- Supports Coral Growth: Helps maintain phosphorus needed for normal coral metabolism and protein synthesis
- Supports Coloration: Balanced nutrient availability can support healthy coloration in corals and macroalgae
- Concentrated Formula: Contains 3,500 mg/L phosphate for precise manual or automated dosing
- No Added Dissolved Organics: Raises phosphorus without introducing an organic nutrient source
- Manual or Automated Dosing: May be added manually or used with a compatible dosing pump
- 250 mL Bottle: Convenient size for home reef aquariums and controlled nutrient management
Product Information
- Brand: Seachem
- Product: Reef Phosphorus
- Size: 250 mL
- Product Type: Reef aquarium phosphorus supplement
- Concentration: 3,500 mg/L phosphate
- Elemental Phosphorus: 0.117%
- Source: Sodium phosphate
- Aquarium Type: Marine and reef aquariums
- General Phosphate Range: Approximately 0.02–0.05 mg/L
Best Used For
- Reef aquariums with consistently low phosphate
- Ultra-low nutrient reef systems
- SPS-dominant reef aquariums
- Mixed reef aquariums
- Systems using aggressive nutrient export
- Aquariums with heavy protein skimming or filtration
- Reef systems using phosphate-removing media
- Maintaining balanced nitrogen and phosphorus availability
- Supporting coral and macroalgae nutrition
Beginner Dosing Directions
Use one-half capful, or 2.5 mL, of Seachem Reef Phosphorus for every 40 US gallons of aquarium water once weekly or as needed to maintain the desired phosphate concentration.
The beginner dose raises phosphate by approximately 0.05 mg/L. Test the aquarium before dosing and avoid adding Reef Phosphorus when phosphate is already within or above the desired range.
Advanced Dosing Formula
To calculate a specific phosphate increase, use Seachem’s dosing formula:
0.31 × aquarium volume in liters × desired phosphate increase in mg/L = milliliters of Reef Phosphorus
For example, raising phosphate by 0.05 mg/L in a 160-liter aquarium requires approximately 2.5 mL of Reef Phosphorus.
One US gallon equals approximately 3.8 liters. Use the aquarium’s estimated actual water volume after accounting for rock, substrate, equipment, and displacement.
Approximate Dosing Examples
- 10 Gallons: Approximately 0.63 mL raises phosphate by about 0.05 mg/L
- 20 Gallons: Approximately 1.25 mL raises phosphate by about 0.05 mg/L
- 40 Gallons: 2.5 mL raises phosphate by about 0.05 mg/L
- 75 Gallons: Approximately 4.7 mL raises phosphate by about 0.05 mg/L
- 100 Gallons: Approximately 6.25 mL raises phosphate by about 0.05 mg/L
These are proportional estimates based on Seachem’s beginner dose. Test before and after dosing rather than relying only on calculated values.
Testing & Target Levels
Seachem states that ideal phosphate levels vary between aquariums but generally fall between approximately 0.02 and 0.05 mg/L phosphate. The appropriate level depends on coral demand, feeding, nutrient export, algae growth, and the overall balance of the aquarium.
Raise phosphate slowly over several days when levels are extremely low. Corals, bacteria, algae, and other organisms may consume phosphorus quickly, particularly in nutrient-limited systems.
Test regularly until a consistent dosing routine maintains a stable concentration. Avoid making large corrections based on a single test result.
Why Phosphorus Matters
Phosphorus is required for essential biological processes, including energy transfer, protein synthesis, cellular activity, and growth. Corals and macroalgae require phosphorus along with nitrogen and other nutrients.
Excess phosphate may contribute to nuisance algae or interfere with reef aquarium management, but phosphate levels that remain too low can also limit biological growth. Reef Phosphorus allows aquarists to add a measured amount when testing confirms supplementation is appropriate.
Balancing Nitrogen & Phosphorus
Phosphate should not be managed without considering nitrogen availability. A reef aquarium may have low phosphate, low nitrate, or an imbalance between the two nutrients.
Seachem recommends using Reef Nitrogen when nitrogen supplementation is also required. Test both nitrate and phosphate before adjusting either nutrient, and make gradual changes based on the aquarium’s response.
Dosing Tips
- Test phosphate before every initial adjustment
- Use a reliable low-range marine phosphate test
- Calculate dosage using actual aquarium water volume
- Raise very low phosphate gradually over several days
- Use a dosing syringe for amounts smaller than one capful
- Add the supplement to a high-flow area of the aquarium
- Monitor nitrate and phosphate together
- Reduce or stop dosing if phosphate continues to rise
- Review phosphate-removing media if supplementation is repeatedly required
- Keep a dosing and testing log to identify the aquarium’s consumption rate
Important Reef Aquarium Note
Reef Phosphorus should be used only when testing confirms that phosphate supplementation is needed. Pale coral coloration, slow growth, reduced polyp extension, or tissue problems can have many causes and do not independently confirm phosphorus deficiency.
Check salinity, temperature, alkalinity, calcium, magnesium, nitrate, phosphate, lighting, water flow, pests, and overall aquarium stability before assuming that low phosphorus is the primary problem.
Overdosing phosphate may contribute to nuisance algae growth or unwanted nutrient accumulation. Dose conservatively and allow time for the aquarium to respond.
Frequently Asked Questions
What is Seachem Reef Phosphorus used for?
Reef Phosphorus is used to increase phosphate in marine and reef aquariums where testing confirms that phosphorus levels are too low.
How much Reef Phosphorus should I use?
The beginner dose is 2.5 mL per 40 US gallons once weekly or as needed. This raises phosphate by approximately 0.05 mg/L.
What phosphate level does Seachem recommend?
Seachem states that ideal levels vary but generally range from approximately 0.02 to 0.05 mg/L phosphate.
Does 1 mL per 20 gallons raise phosphate by 0.02 ppm?
No. Based on Seachem’s official concentration, approximately 1.25 mL per 20 gallons raises phosphate by about 0.05 mg/L. One milliliter per 20 gallons would raise it by approximately 0.04 mg/L.
Why would a reef aquarium need added phosphate?
Phosphorus may become limited in aquariums with aggressive nutrient export, low feeding, strong protein skimming, phosphate-removing media, or high biological consumption.
Is Reef Phosphorus a phosphate remover?
No. Reef Phosphorus adds phosphate. Products such as PhosGuard, PhosBond, or other phosphate-removing media serve the opposite purpose.
Can Reef Phosphorus cause algae growth?
Excessive phosphate may contribute to nuisance algae. Test regularly and add only enough product to maintain the desired concentration.
Can it be used in an SPS reef aquarium?
Yes. It may be used in SPS systems when testing confirms that phosphate is below the desired level. Raise the concentration gradually and monitor coral response.
Can it be used in a mixed reef aquarium?
Yes. Reef Phosphorus may be used in mixed reef systems when phosphate supplementation is needed and dosing is based on accurate testing.
Should I test nitrate too?
Yes. Nitrogen and phosphorus availability should be considered together because an imbalance may limit coral or macroalgae growth.
Can Reef Phosphorus be used with an automatic doser?
Yes. Seachem states that the product may be manually dosed or used with a compatible dosing system to maintain a stable concentration.
Should I stop using phosphate-removing media?
Review the need for phosphate-removing media if phosphate remains too low. Adding Reef Phosphorus while aggressively removing phosphate may create an inefficient dosing cycle.
Available at Tropical Treasures Wyo
Seachem Reef Phosphorus 250 mL provides a concentrated phosphate source for reef aquariums with confirmed low phosphorus levels. Visit Tropical Treasures Wyo in Cheyenne, Wyoming, to shop Seachem reef supplements, phosphate and nitrate test kits, dosing supplies, filtration media, reef foods, and aquarium care essentials.
Explore More Aquarium Products:
Low stock: 1 left
Couldn't load pickup availability
Explore Related Aquarium Products: