| Tank | Exterior L × W × H (in) | Calculated | Actual water | Litres | Weight (lb) |
|---|---|---|---|---|---|
| Shallow pico cube | 6.29 × 6.29 × 3.14 | 0.54 gal | 0.47 gal | 1.8 | 3.9 |
| Pico cube | 6.29 × 6.29 × 6.29 | 1.08 gal | 0.94 gal | 3.5 | 7.8 |
| Tall pico | 6.29 × 6.29 × 9.44 | 1.62 gal | 1.41 gal | 5.3 | 11.7 |
| 20 cm cube | 7.87 × 7.87 × 7.87 | 2.11 gal | 1.84 gal | 6.9 | 15.3 |
| 2.5 gal framed | 12 × 6 × 8 | 2.49 gal | 2.17 gal | 8.2 | 18.1 |
| Nano rectangle 30 cm | 12.2 × 7.48 × 7.48 | 2.95 gal | 2.57 gal | 9.7 | 21.4 |
| Tall nano 20 cm | 7.87 × 7.87 × 11.81 | 3.17 gal | 2.75 gal | 10.4 | 23.0 |
| Tall rectangle 30 cm | 12.2 × 7.48 × 9.44 | 3.73 gal | 3.24 gal | 12.3 | 27.1 |
| 25 cm cube | 9.84 × 9.84 × 9.84 | 4.12 gal | 3.59 gal | 13.6 | 29.9 |
| Nano rectangle 36 cm | 14.17 × 8.66 × 8.66 | 4.60 gal | 4.00 gal | 15.2 | 33.4 |
| 5 gal framed | 16 × 8 × 10 | 5.54 gal | 4.82 gal | 18.2 | 40.2 |
| 5.5 gal framed | 16.19 × 8.38 × 10.5 | 6.17 gal | 5.37 gal | 20.3 | 44.7 |
| Tall rimless 36 cm | 14.17 × 8.66 × 11.02 | 5.85 gal | 5.09 gal | 19.3 | 42.5 |
| Shallow rimless 45 cm | 17.71 × 11.02 × 7.08 | 5.98 gal | 5.20 gal | 19.7 | 43.4 |
| Long rimless 60 cm | 23.62 × 7.87 × 7.87 | 6.33 gal | 5.51 gal | 20.9 | 46.0 |
| 30 cm cube | 11.81 × 11.81 × 11.81 | 7.13 gal | 6.20 gal | 23.5 | 51.7 |
| 10 gal framed | 20 × 10 × 12 | 10.39 gal | 9.04 gal | 34.2 | 75.4 |
Actual water applies a 0.87 factor for 5 mm glass, a 1-inch fill gap and minor displacement. Sizes follow common rimless nano series dimensions; measure your own tank for exact figures.
Why nano volume is trickier
Everything that reduces volume is a fixed thickness: 5 mm of glass, an inch of air at the top, an inch of soil. On a 6-inch cube those fixed amounts are a quarter of the tank. The same glass and gap on a 48-inch tank are under a tenth. Nano keepers should always dose from the actual water figure, and should keep a cup measure handy: in a 1-gallon pico, a single teaspoon of fertiliser is a full dose.
Measuring a nano tank
Use millimetres if your tape has them. Measure inside the glass; on a rimless tank the top edge makes that easy. Enter the real water line, which on a 20 cm cube is often 17 or 18 cm, and the real soil depth, which can be 3 to 5 cm in a planted scape.