Estimate rectangular aquarium water volume, choose a water-change share and work out how many bucket fills to prepare.
Exported by the iOS App After importing, edit the numbers in Calvance.
For a rectangular aquarium measured on the inside, up to the actual waterline. This English example uses inches and US liquid gallons. Displacement is your measured or estimated effective volume, not a fixed allowance for all tanks. Save the tank and bucket parameters for later changes.
| Inputs | Default |
|---|---|
| Internal tank length (in) | 24 |
| Internal tank width (in) | 12 |
| Actual water depth from the inner bottom (in) | 14 |
| Effective water displaced by substrate and decor (gal US) | 1.5 |
| Chosen water-change percentage (%) | 25 |
| Usable bucket capacity (gal US) | 2 |
Multiply internal length, width and actual water depth, then subtract effective displacement. Multiply net water by your chosen change percentage; divide that amount by usable bucket capacity and round up. At 24 × 12 × 14 in, gross water is 192/11 US gal. Subtracting 1.5 US gal leaves 351/22 US gal. A 25% change is 351/88 US gal, about 3.99, requiring two fills of a 2 US gal bucket. The last fill may be partial.
24 [Internal tank length in] × 12 [Internal tank width in] × 14 [Actual water depth from the inner bottom in] → Geometric water volume before displacement gal US
Geometric water volume before displacement gal US-1.5 [Effective water displaced by substrate and decor gal US] → Estimated net water volume gal US
Estimated net water volume gal US × 25 [Chosen water-change percentage]% → Water volume to replace gal US
Estimated net water volume gal US-Water volume to replace gal US → Water remaining after draining gal US
ceil(Water volume to replace gal US/2 [Usable bucket capacity gal US]) → Bucket fills needed, including a partial fill
Change only the water-change share from 25% to 30%. Water to replace rises from about 3.99 to 4.79 US gal, and bucket fills rise from two to three. Tank dimensions, displacement and bucket capacity stay unchanged.
| Result | Default | Changed |
|---|---|---|
| Geometric water volume before displacement (gal US) | 17.45 | 17.45 |
| Estimated net water volume (gal US) | 15.95 | 15.95 |
| Water volume to replace (gal US) | 3.99 | 4.79 |
| Water remaining after draining (gal US) | 11.97 | 11.17 |
| Bucket fills needed, including a partial fill | 2 | 3 |
Results are displayed to at most two decimal places; later formulas use unrounded values.
Dimensions and net water must be positive; displacement must be nonnegative and smaller than gross water. Choose 0–100% and a positive bucket capacity. Zero and 100% are mathematical boundaries, not maintenance advice. Porous substrate is not a solid block: its full geometric volume is not automatically its water displacement. For measured net water, replace the net-volume expression with that value. US liquid gallons differ from imperial gallons. This estimate recommends no change frequency, livestock plan or chemical dose.
Compare a geometric volume tool: Bulk Reef Supply.
Download and import into Calvance to edit the numbers. The canvas does not reject every invalid input; check the stated ranges.
It can differ from water actually present because of internal dimensions, waterline and displaced volume. Measured net water is preferable.
No. The count rounds up; fill the final bucket only with the remaining required amount.
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