Flourish vs APT 3: nutrient role and daily versus weekly dosing
By Richard James · Manufacturer sources checked · 28 October 2026
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Quick answer
Flourish and APT 3 differ in nutrient coverage and schedule. Use the actual formulation and current instructions, rather than treating both as the same “complete fertiliser.”
Compare purpose before volume
Flourish is a micronutrient-focused supplement; APT 3 is sold with broader macro/micronutrient coverage. Neither description establishes that the aquarium has a measured deficiency. Check the declared analysis and existing nutrient sources.
APT 3’s current daily reference
The maker publishes 3 mL per 100 L daily and directs non-CO₂/slow-grower cases to adjustment guidance. Use those current daily directions rather than carrying over a different schedule. The APT 3 calculator now occupies the established APT page.
A simple schedule worksheet
Write “amount per application” and “applications per week” in separate columns for each bottle. Multiplication gives a weekly liquid total, not equivalent nutrient mass or permission to add a whole week at once. Do not keep an old Flourish schedule while substituting the same millilitres of APT 3.
What cannot this comparison tell you?
There is no controlled growth trial here or blanket algae/shrimp-safety verdict. Watch and record changes under a documented routine. Flourish calculator · APT 3 calculator.
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.