Flourish Excel: intended use, plant cautions and dosing modes

Two modes, not two additions to stack

Seachem distinguishes initial use or a major water change greater than 40% from routine use. Its references are 5 mL per 40 L initially and 5 mL per 200 L daily or every other day thereafter. Select the applicable Excel mode; do not add both results together.

Remove the old algae spot-dose recipe

Seachem says Excel is not produced or marketed as an algicide and warns that overdosing or applying it directly to a plant can cause damage. This guide does not prescribe a concentrated injection, higher algae-killing amount or filter-off spot-treatment routine.

Plant cautions are product-specific

The manufacturer notes sensitivity in Anacharis and discusses variable Vallisneria responses. Read its FAQ for the plants you keep rather than assuming every plant behaves identically. A precise calculation does not guarantee compatibility.

Check the arithmetic

If a dose is calculated for 20 units of water but only 15 are present, the amount per unit is 20 ÷ 15 = 1.333 times the intended reference: about 33.3% higher, not “triple strength”. This corrects the old article's arithmetic; it is not an overdose threshold or permission to exceed instructions.

Keep a useful plant-care record

Record the mode, actual amount, date, water changes and observed growth. Change a plan based on the relevant directions and evidence rather than a promised algae-free deadline. This page does not replace assessment of lighting, nutrients or the aquarium's other conditions.

Sources and review scope

Seachem Flourish Excel directions and FAQ. Reviewed 28 October 2026. Published manufacturer directions and editorial claims; not an independent clinical or efficacy assessment.

Related practical guides

• Aquarium product strengths: why similar bottles need different doses