Dosing and testing: two different questions
By Richard James · Calculation and editorial review · 28 October 2026
A calculated amount describes an addition based on selected instructions. A water test describes a measured property under that test's method. Neither is a substitute for the other.
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Record them together
| Calculation record | Test record |
|---|---|
| Exact product, formulation and application. | Exact kit, units and parameter. |
| Water amount and measurement assumption. | Sampling time and relevant aquarium conditions. |
| Actual amount and time added. | Observed reading and the method's limitations. |
A result is not a corrective-dose formula
Do not multiply a standard amount by a test reading unless the exact manufacturer's instructions establish that calculation. An amount displayed by this site does not measure the concentration remaining after adsorption, water replacement or other changes.
Some products explicitly require testing
The Cupramine guide explains why a scheduled addition does not override copper testing. The Prime emergency guide separately discusses the limits of emergency claims and test interpretation. Do not transfer either product's rules to another bottle.
Investigate disagreement
If an observation conflicts with expectations, check the units, procedure, product history and source instructions. Obtain appropriate advice when the interpretation is unclear. This guide does not select a treatment from a single reading or promise that a neutralised substance will disappear from every test.
Method and review scope
Reviewed 28 October 2026 against the published calculation methodology and the linked product-specific guides. Calculation and editorial review; examples are arithmetic, not treatment or livestock-safety prescriptions.
Practical next steps
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Seachem Cupramine, 50 mL
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