Flourish vs API Leaf Zone: nutrient coverage and weekly amounts
By Richard James · Manufacturer sources checked · 28 October 2026
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Quick answer
Leaf Zone and Flourish have different declared nutrient profiles. A claim that a product helps leaves does not diagnose the cause of a yellow leaf or identify every missing nutrient.
Start with the analysis
API identifies chelated iron and potassium and gives a weekly reference of 5 mL per 10 US gallons (38 L on its label). Flourish has a broader micronutrient role. These descriptions do not justify calling either a complete substitute for every macro/micronutrient need.
Do not compare nutrient strength by millilitres
A larger liquid amount does not mean it supplies more of every nutrient. You need the declared composition and reporting basis to compare contributions. Keep elemental phosphorus distinct from phosphate declarations and do not read a bottle percentage as the aquarium concentration.
Will it fix holes or yellowing?
Record affected species, old versus new growth, timing and recent changes. A symptom alone cannot select the right product or amount. API’s FAQ notes that Leaf Zone can stimulate algae; review the amount and aquarium conditions rather than assuming a universal exclusion.
Use the right reference
Leaf Zone calculator · Flourish calculator · Read nutrient categories.
Keep the result in context
Use actual water volume and the exact schedule. Do not equate the liquid millilitres with active nutrient mass. Read units and concentration and schedule changes before comparing a daily and weekly routine.
Sources and check scope
Sources checked 28 October 2026. Manufacturer product information and scoped instructions; no independent efficacy or clinical review. This source check was assisted by AI; it is not an independent human expert or veterinary review. Match the exact pack and consult its manufacturer if directions conflict.