Reef · Dosing
How to Scale Reef Supplement Directions Without Guessing
A reliable reef-dose calculation starts with the bottle in your hand, not a brand preset copied months ago. This guide shows the audit trail: exact label, net water volume, fresh test, chosen target, and a documented livestock limit.
The Reef Supplement Dose Calculator performs only the proportional math described here. It does not select a target, store product concentrations, or declare a universal safe change rate.
The five inputs you should be able to audit
- Exact current product directions. Record the stated dose, reference water volume, parameter increase, concentration or preparation method, and any maximum or spacing instruction.
- Net operating water volume. Account for the display, sump, rock, sand, equipment, and normal operating level instead of using the advertised glass-box size.
- A repeatable current measurement. Confirm an unexpected result before changing the aquarium.
- A documented target. The target must come from the livestock and system care plan, not from a calculator default.
- A maximum 24-hour change. Use a limit from the exact product directions or a qualified livestock care plan. If you cannot document one, stop rather than substitute a generic internet rule.
The label-scaling equation
Suppose a label states that a certain number of milliliters treats a stated volume and produces a stated parameter increase. The transparent scaling equation is:
dose = label mL × (system volume ÷ label volume) × (needed change ÷ label change)
This equation is unit conversion, not a safety decision. The label volume and system volume must use the same unit. The label change, current measurement, and target must also use the same parameter unit.
Why BenchCalcs removed brand presets
A brand name is not enough to identify a dose. Product versions, concentrations, preparation instructions, and packaging can change. A homemade solution may also depend on how it was mixed. A preset can look authoritative while silently describing a different formulation from the one beside the aquarium.
The safer design makes the user transcribe the current directions. It is less convenient than a one-click brand menu, but every number has a visible source and can be checked before anything is added to living water.
Net volume is part of the dose
Supplement directions scale with water volume. Display-tank capacity alone can overstate the water actually present because rock, sand, equipment, and headspace displace water. A sump can add water back. Use the best defensible net system estimate you have and keep that estimate in the dosing log.
If the aquascape, sump level, or equipment changes materially, revisit the estimate rather than treating volume as permanent.
Correction and maintenance are different questions
Correction is the positive difference between a fresh current measurement and a chosen target. If the target is below the current result, adding more supplement cannot perform the correction; the calculator therefore returns zero.
Maintenance replaces a decline actually observed over time. Do not select a generic “low,” “medium,” or “high” coral profile. Log the parameter at the same time under a stable routine, record every dose, and enter a daily decline only when the trend is repeatable enough to distinguish it from testing noise.
A multi-day result is still conditional
The calculator compares the needed change with the maximum 24-hour change that you entered. When the correction is larger, it shows a minimum number of days and rounds the calculated daily amount down.
That is not permission to queue every dose in advance. Re-test before each next stage. Stop when the target is reached, the trend changes, a test looks wrong, or livestock responds poorly. The newest observation overrides the old plan.
Keep a small dosing audit trail
| Record | Why it matters |
|---|---|
| Product name, concentration, lot or version | Prevents reuse of directions after a product or preparation changes |
| Label dose, reference volume, and stated change | Makes the arithmetic independently checkable |
| Net water-volume estimate and date | Shows the scaling assumption |
| Test method, result, and time | Separates a trend from inconsistent timing or technique |
| Actual amount added and follow-up result | Shows whether the aquarium responded as expected |
Stop instead of calculating when
- the product label, concentration, or preparation is uncertain;
- the label and selected calculator units do not match;
- the current test is surprising or cannot be reproduced;
- the desired target or 24-hour livestock limit is undocumented;
- multiple additives changed at once, making the cause of a trend unclear;
- the aquarium shows stress, clouding, precipitation, or another unexpected response.
What manufacturer sources support here
Bulk Reef Supply's mixing instructions and the Red Sea Reef Foundation supplement guide are examples of product-specific preparation, testing, and dosing directions. BenchCalcs cites them to document why the exact product instructions control. It does not reproduce their numeric dose tables as universal defaults.
The practical rule
If you cannot point to the source of every input, you do not yet have a dosing calculation—only a guess. Preserve the label, measurement, volume assumption, target source, and daily limit together. Then use the calculator for the arithmetic and the aquarium's next test for the decision.