Aquarium product strengths: why similar bottles need different doses
By Richard James · Manufacturer sources reviewed 28 October 2026
Match the exact formulation and application before reusing a dose. Similar branding, bottle sizes or cap shapes do not establish an equivalent product. A concentration comparison alone does not prove that two medicines can be substituted.
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Check these four things on your label
- Exact product. Match the full name, strength and formulation—including Aquarium, Pond or Marine.
- Amount and timing. Read the dose, water volume, units and frequency together. Bottle size is not the dose.
- Preparation and warnings. Check filtration, livestock and other-product restrictions in the leaflet.
- Match your calculation. Confirm the selected mode and water units. If the bottle and calculator disagree, resolve the difference before dosing.
Real manufacturer examples: what changes?
Ich-X: find Aquarium or Pond
Hikari’s current directions distinguish 5 mL per 10 US gallons for aquarium Ich-X from 5 mL per 50 US gallons for Pond Solutions Ich-X. For the same illustrative 20 US gallons, these scale to 10 mL and 2 mL respectively. This comparison explains bottle identification; it does not select a treatment.
Open Hikari’s actual product directions · Check the Ich-X calculator
Prime: find which water volume the instructions mean
Seachem’s standard reference is 5 mL per 200 L of new water. For direct aquarium addition, Seachem bases the amount on aquarium volume. The same bottle therefore needs a different volume input depending on how it is used. Exceptions are outside this normal-use illustration.
Open Seachem’s actual Prime directions · Check the Prime calculator
Cupramine: read “Before Treating” first
Seachem instructs removal of invertebrates and excludes other medicines and reducing agents such as conditioners/ammonia binders. A calculated quantity does not remove those restrictions or replace copper testing.
Open Seachem’s actual Cupramine directions · Check its calculator and preparation checklist
Next: can you measure the result?
Once the exact product and applicable amount are established, practise reading a small liquid-volume scale.
Similar names can mean different purposes
Seachem describes Flourish as a plant nutrient supplement and Flourish Excel as an organic carbon source. The shared word “Flourish” does not make them replacement bottles or establish a volume conversion.
Likewise, a larger bottle can simply contain more of the same formulation. Do not assume either that every larger pack is stronger or that every same-brand pack has identical directions.
A ratio is not a substitution instruction
If two hypothetical solutions contain 10 mg/mL and 20 mg/mL of one ingredient, 2 mL of the first and 1 mL of the second each contain 20 mg of that ingredient. That arithmetic does not account for other ingredients, intended use, stability or compatibility. It cannot authorise swapping medicines.
Common questions
Can I reuse last month’s dose after buying a new bottle?
Only after confirming the same applicable formulation, instructions and water volume. A matching brand is not enough.
What if my exact bottle is missing?
Do not choose a nearby product as a proxy. Report the exact bottle with its instructions.
What if the bottle and website disagree?
Use the conflicting-instructions checklist instead of averaging the references.
Sources and review scope
Manufacturer examples checked 28 October 2026. These explain how to read instructions; they are not hands-on product tests.
- Seachem Prime directions — new-water versus direct-addition scope
- Seachem Cupramine directions — preparation restrictions
- Hikari Ich-X directions — aquarium and pond formulation references
- Seachem Flourish — product purpose
- Seachem Flourish Excel — distinct product purpose
Reviewed 28 October 2026. Worked examples and worksheets are DoseMyTank explanations, not laboratory tests or evidence of a particular aquarium’s response. Manufacturer instructions apply to the exact product, device and conditions described. Obtain clarification where your supplied instructions differ.
Related practical guides
Optional buying links
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Seachem Prime, 500 mL
View on Amazon US (affiliate link) — Seachem Prime, 500 mL; opens in a new tabCheck the selected bottle, formulation and label before buying. These links do not select a treatment or change your dose. Prices, sellers and availability are shown on Amazon. About these links.
Optional buying links
Find this product
Affiliate links. As an Amazon Associate I earn from qualifying purchases.
Seachem Flourish Excel, 500 mL
View on Amazon US (affiliate link) — Seachem Flourish Excel, 500 mL; opens in a new tabCheck the selected bottle, formulation and label before buying. These links do not select a treatment or change your dose. Prices, sellers and availability are shown on Amazon. About these links.
Optional buying links
Find this product
Affiliate links. As an Amazon Associate I earn from qualifying purchases.
Seachem Cupramine, 50 mL
View on Amazon US (affiliate link) — Seachem Cupramine, 50 mL; opens in a new tabCheck the selected bottle, formulation and label before buying. These links do not select a treatment or change your dose. Prices, sellers and availability are shown on Amazon. About these links.