20 Gallon Long vs 20 High: Differences Explained
Both hold about 20 gallons, but one is long and low and the other is short and tall. Here's when each one makes sense.
Aquarium guides
Practical guides on tank sizes, weight, measuring and setup, written to go with our calculators.
20 Long vs 29 Gallon: Which Fish Tank to Choose
Same footprint, 6 inches of height apart. How the 20 long and 29 gallon compare on volume, weight, equipment and fish.
40 Breeder vs 55 Gallon: Which Tank Is Better?
The 40 breeder is wide and shallow, the 55 is long and narrow. Here's how they compare and which one suits your plans.
Aquarium Gallons to Litres: Conversion Chart
US gallons, UK gallons and litres explained, with a conversion chart for every standard tank size.
What Size Heater Do I Need for My Aquarium?
The 3–5 watts per gallon rule, a heater and filter chart for every tank size, and when two heaters beat one.
How Much Does a Fish Tank Weigh? Every Size Compared
A full aquarium weighs about 10 lb per gallon once you add glass, water and gravel. Here's the weight of every common size.
How Much Gravel Do I Need for My Aquarium?
The 1 lb per gallon rule only works for some tanks. Here's the footprint method and a gravel table for every size.
How to Measure a Fish Tank for Size and Volume
Inside or outside measurements, how to handle bowfronts and corner tanks, and the quick way to turn inches into gallons.