Source: https://guthlabs.ai/docs/instruments/aquarium-volume-stocking-calculator/mechanism/

instrument mechanism / verified-clean

# Aquarium Volume & Stocking Calculator mechanism

The inspectable method record for Aquarium Volume & Stocking Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The rectangular-tank volume equation is mathematically correct under the stated inch and US-gallon assumptions. The instrument cannot receive an unconditional PASS because the alternative stocking method is undefined and the selected heuristic is inherently approximate; the honest-label warning is appropriate but should be displayed prominently alongside the result.

- The volume formula is correct for rectangular tanks when L, W, and H are measured in inches: volume_gal = (L × W × H) / 231.

- The 1-inch-per-gallon method is a commonly cited hobbyist rule of thumb, but it is not a reliable general stocking formula and must not be presented as a safe biological limit.

- The specification offers either the 1-inch-per-gallon rule or a surface-area/bioload-adjusted method, but it does not define the latter formula, inputs, coefficients, or calculation procedure.

- The stocking calculation does not specify whether fish length means adult total length, standard length, or another measurement; adult size is mentioned but the aggregation rule is not explicitly defined.

- The formula calculates nominal gross tank volume and does not account for substrate, decorations, equipment displacement, fill height, filtration capacity, oxygenation, territorial behavior, species compatibility, or waste production.

## Units and conventions

- Tank dimensions L, W, and H are positive measurements in inches.

- 231 cubic inches equals exactly 1 US liquid gallon.

- The test vectors use the explicitly selected 1-inch-per-gallon freshwater heuristic, not the undefined surface-area/bioload-adjusted method.

- Stocking capacity is interpreted as maximum aggregate adult fish length in inches equal to calculated gallons.

- Fish lengths are adult total lengths in inches, and current stocking is the sum of those adult lengths.

- Displayed gallon values are rounded to two decimal places only after calculation; stocking arithmetic uses the unrounded volume.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "method": "one_inch_per_gallon",
    "length_in": 48,
    "width_in": 13,
    "height_in": 20,
    "fish_adult_lengths_in": [
      6,
      4,
      4,
      2
    ]
  },
  "expected_outputs": {
    "volume_gal": 54.03,
    "maximum_aggregate_adult_fish_length_in": 54.03,
    "current_aggregate_adult_fish_length_in": 16,
    "remaining_rule_of_thumb_capacity_in": 38.03,
    "status": "within heuristic"
  },
  "working": "1. Tank volume = (48 × 13 × 20) / 231 = 12,480 / 231 = 54.025974... gal, displayed as 54.03 gal. 2. Maximum aggregate adult length under the heuristic = 54.025974... × 1 in/gal = 54.025974... in, displayed as 54.03 in. 3. Current aggregate length = 6 + 4 + 4 + 2 = 16 in. 4. Remaining heuristic capacity = 54.025974... − 16 = 38.025974... in, displayed as 38.03 in."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification exposes multiple failure hazards: zero dimensions can yield a numerically valid but physically impossible zero-gallon tank, enormous dimensions overflow to Infinity, the adjusted stocking branch lacks enough formula detail to compute an output, and negative dimensions can produce a physically meaningless negative volume unless an explicit sign convention and validation rule are implemented.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/aquarium-volume-stocking-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/aquarium-volume-stocking-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/aquarium-volume-stocking-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`