Tank volume is calculated from length, width, and height in inches, then converted to gallons and liters. The calculator derives all other results as multipliers: water weight uses 8.34 lbs/gal; gravel uses 1.5 lbs/gal for a 2-inch bed; heater sizing applies 4 watts per gallon; filter flow assumes 3 GPH per gallon; fish capacity follows the 1 inch of fish per gallon rule as a starting baseline.
The 1 inch of fish per gallon is a rough guideline and varies widely. Small, active fish like tetras need less space per inch, while large territorial fish need more. Goldfish and plecos are exceptions — they need 20+ gallons each.
Water weighs 8.34 lbs per gallon. Add the tank glass, stand, substrate, rocks, and decorations. A 55-gallon tank typically weighs 500+ lbs when fully set up. Always verify your floor can handle the weight.
Many species like goldfish, plecos, and tetras prefer 72-76°F. Even "cold-water" tanks often need a heater to maintain stable temperature. The 4 watts-per-gallon rule assumes tropical (75-78°F) conditions.
Run the filter 24/7. The GPH calculation assumes continuous operation for biological filtration. Turning it off harms the beneficial bacteria colony that removes ammonia and nitrite.
Yes for volume and basic dimensions, but saltwater requires higher-flow filtration (often 5-10x turnover per hour vs. 3x) and additional equipment like protein skimmers. Adjust the filter GPH upward for marine setups.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.