curl --request POST \
  --url https://api.iotools.cloud/v1/tool/aquarium-substrate-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "tankShape": "rectangular",
  "unit": "in",
  "length": "24",
  "width": "12",
  "depth": "2",
  "substrateType": "gravel"
}
'

{
  "tool": "aquarium-substrate-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "results": [
      {
        "metric": "Tank Shape",
        "value": "Rectangular"
      },
      {
        "metric": "Area",
        "value": "2.00 ft² (288.00 in² / 1858.06 cm²)"
      },
      {
        "metric": "Volume",
        "value": "0.33 ft³ (9.44 L)"
      },
      {
        "metric": "Substrate",
        "value": "Gravel (100 lb/ft³)"
      },
      {
        "metric": "Estimated Weight",
        "value": "33.33 lb (15.12 kg)"
      },
      {
        "metric": "Bags Needed",
        "value": "7 × 5-lb bags, or 4 × 10-lb bags"
      },
      {
        "metric": "Depth Guidance",
        "value": "1-2 in for fish-only tanks; 2-3 in if capping with root-feeding plants."
      }
    ]
  },
  "credits_used": 5,
  "credits_remaining": null
}