Seachem Flourish Excel 500 mL – Planted Aquarium Carbon Supplement
Seachem Flourish Excel 500 mL is a bioavailable organic carbon supplement formulated for freshwater planted aquariums. Carbon is an essential nutrient used by aquatic plants during photosynthesis and the production of new leaves, stems, and roots.
Flourish Excel provides plants with a readily available source of carbon that may be used as an alternative to injected carbon dioxide in many low-tech aquariums or alongside a pressurized CO₂ system. It also helps maintain iron in the more readily usable ferrous form.
Key Features
- Bioavailable Carbon Source: Supplies organic carbon that freshwater aquarium plants can use during growth
- Alternative to CO₂ Injection: Useful for planted aquariums without pressurized carbon-dioxide equipment
- Compatible with Injected CO₂: May also be used alongside a pressurized CO₂ system
- Supports Plant Growth: Helps provide carbon needed for healthy leaves, stems, roots, and overall development
- Iron-Reducing Properties: Helps promote the ferrous form of iron, which is more readily used by plants
- Convenient Liquid Formula: Easy to measure and add during a regular planted-aquarium routine
- Large 500 mL Bottle: Suitable for medium and larger planted aquariums or continued use
Product Information
- Brand: Seachem
- Product: Flourish Excel
- Size: 500 mL
- Equivalent Size: Approximately 17 fl oz
- Product Type: Planted-aquarium organic carbon supplement
- Aquarium Type: Freshwater planted aquariums
- Initial or Major Water-Change Dose: 5 mL per 10 gallons
- Maintenance Dose: 5 mL per 50 gallons daily or every other day
Best Used For
- Low-tech freshwater planted aquariums
- Aquariums without pressurized CO₂ injection
- Planted tanks using supplemental injected CO₂
- Community aquariums containing live plants
- Supporting active plant growth
- Routine planted-aquarium fertilization schedules
- Aquariums where additional available carbon is desired
- Medium and larger planted aquariums
How to Use
On initial use or after a major water change greater than 40%, add one capful, or 5 mL, of Seachem Flourish Excel for every 10 US gallons of aquarium water.
After the initial dose, add one capful, or 5 mL, for every 50 US gallons daily or every other day. Each thread inside the cap represents approximately 1 mL for measuring smaller aquariums.
Calculate dosage using the aquarium’s actual water volume. Substrate, rocks, driftwood, decorations, and equipment reduce the amount of water inside the aquarium compared with its listed capacity.
Maintenance Dosage Guide
- 5-Gallon Aquarium: Approximately 0.5 mL daily or every other day
- 10-Gallon Aquarium: Approximately 1 mL daily or every other day
- 20-Gallon Aquarium: Approximately 2 mL daily or every other day
- 40-Gallon Aquarium: Approximately 4 mL daily or every other day
- 50-Gallon Aquarium: 5 mL daily or every other day
- 75-Gallon Aquarium: Approximately 7.5 mL daily or every other day
- 100-Gallon Aquarium: 10 mL daily or every other day
These amounts are proportional calculations based on Seachem’s official maintenance dosage. Always follow the current instructions printed on the bottle.
Initial or Major Water-Change Dosage Guide
- 5-Gallon Aquarium: Approximately 2.5 mL
- 10-Gallon Aquarium: 5 mL
- 20-Gallon Aquarium: 10 mL
- 40-Gallon Aquarium: 20 mL
- 50-Gallon Aquarium: 25 mL
- 75-Gallon Aquarium: Approximately 37.5 mL
- 100-Gallon Aquarium: 50 mL
The larger initial dose is intended only for first use or after a water change greater than 40%. Do not use the initial dose as the regular daily dosage.
Flourish Excel and CO₂ Injection
Flourish Excel may be used as an alternative carbon source in aquariums without pressurized CO₂. It can provide substantial benefits for many planted aquariums without the equipment, regulators, tubing, and monitoring required by a gas-injection system.
It does not provide the same quantity of carbon as a properly managed pressurized CO₂ system. High-demand plants and densely planted aquascapes may still achieve stronger or faster growth with injected carbon dioxide.
Flourish Excel may also be used alongside CO₂ injection. The two methods do not prevent plants from using the other carbon source.
Flourish Excel and Algae
Some aquarium keepers report that certain types of algae, particularly black beard algae, decrease while Flourish Excel is being used. However, Seachem does not manufacture or market Flourish Excel as an algaecide.
Do not overdose the aquarium or apply concentrated Flourish Excel directly to plants as an algae spot treatment. Concentrated exposure may damage leaves, especially on sensitive plant species.
Long-term algae control still depends on balanced lighting, plant nutrition, carbon availability, maintenance, feeding, water changes, and correction of the underlying cause.
Sensitive Plant Considerations
Anacharis is particularly sensitive to Flourish Excel. Seachem recommends dosing every other day rather than daily in aquariums containing Anacharis.
Some aquarists have reported leaf melting in Vallisneria after larger-than-recommended doses. Seachem’s testing found that standard maintenance dosing was generally tolerated, while higher doses were more likely to cause temporary leaf damage.
When using Flourish Excel with sensitive plants, begin conservatively, avoid overdosing, and monitor the plants closely.
Planted Aquarium Tips
- Measure each dose carefully
- Use the larger dose only on initial use or after a water change greater than 40%
- Add the maintenance dose daily or every other day
- Dose during the light period when practical
- Avoid pouring concentrated product directly onto plant leaves
- Reduce dosing frequency around sensitive plants when necessary
- Maintain suitable lighting and complete plant nutrition
- Continue regular water changes and aquarium maintenance
- Monitor fish, shrimp, snails, and plants after dosing
Important Aquarium Care Note
Flourish Excel supplies carbon but is not a complete plant fertilizer. Aquarium plants may also require nitrogen, phosphorus, potassium, iron, trace elements, suitable lighting, and stable water conditions.
Flourish Excel does not replace water conditioning, filtration, water testing, water changes, or proper aquarium maintenance. Do not exceed the recommended dosage in an attempt to accelerate plant growth or control algae.
Keep the product away from children. Avoid ingestion and contact with the eyes. Follow all safety instructions printed on the bottle.
Frequently Asked Questions
What is Seachem Flourish Excel used for?
Flourish Excel supplies a bioavailable organic carbon source for freshwater aquarium plants.
How much Flourish Excel should I use?
On initial use or after a water change greater than 40%, use 5 mL per 10 gallons. Thereafter, use 5 mL per 50 gallons daily or every other day.
Can Flourish Excel replace CO₂ injection?
It can serve as an alternative carbon source in many planted aquariums, but a properly managed pressurized CO₂ system generally supports a greater rate of plant growth.
Can Flourish Excel be used with injected CO₂?
Yes. Seachem states that Flourish Excel may be used alone or alongside carbon-dioxide injection.
Does Flourish Excel contain carbon dioxide?
No. It supplies a bioavailable organic carbon source rather than gaseous CO₂.
Does Flourish Excel affect aquarium pH?
Seachem states that Flourish Excel is not carbon dioxide and does not have the same pH-lowering effect associated with injected CO₂.
Does Flourish Excel kill algae?
Seachem does not market it as an algaecide. Some aquarists observe reduced algae during use, but overdosing or direct spot treatment may damage aquarium plants.
Is Flourish Excel safe for fish?
Yes. Seachem states that it is safe for aquarium fish when used according to the directions.
Is Flourish Excel safe for shrimp and snails?
It is commonly used in planted community aquariums, but dosing should remain within the manufacturer’s directions. Avoid overdosing and monitor sensitive livestock.
Can Flourish Excel be used with Vallisneria?
Standard maintenance dosing is generally tolerated, but larger doses may cause temporary leaf melting. Avoid overdosing and monitor Vallisneria closely.
Can Flourish Excel be used with Anacharis?
Anacharis is sensitive to Flourish Excel. Seachem recommends using it every other day rather than daily in aquariums containing Anacharis.
Should Flourish Excel be dosed in the morning?
Dosing during the light period is ideal because carbon use is associated with photosynthesis. Seachem states that the product may remain available for up to 24 hours, so it can still be dosed at another convenient time.
Does Flourish Excel replace complete plant fertilizer?
No. It supplies carbon but does not replace nitrogen, phosphorus, potassium, iron, trace elements, lighting, or other planted-aquarium requirements.
Available at Tropical Treasures Wyo
Seachem Flourish Excel 500 mL provides a bioavailable organic carbon source for freshwater planted aquariums with or without injected CO₂. Visit Tropical Treasures Wyo in Cheyenne, Wyoming, to shop Seachem plant supplements, live aquarium plants, planted substrates, aquarium lighting, CO₂ equipment, fertilizers, and aquascaping essentials.
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