This is a discussion on How Much Gravel? within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
How many pounds of gravel do I need for a 20 gallon tank? I am getting a new tank for christmas and I need ...
Most people believe in 1-2lb per gallon. Since you will have plants, have you settled on gravel or are other substrates and option? I have pool filter sand in mine and although it took a lot of rinsing, it is a good substrate for plants (about corse seasalt sized granules) and it's VERY cheep! About $8-10 for 50lbs! You can find it at any pool supply store Posted via Mobile Device
As you are starting new with this 20g, I would also consider fish, as some have a substrate preference. Sand works best for the fish who like to browse over and into the substrate, such as corys, loaches. Plants grow well in sand or fine gravel. Darker rather than lighter is best for fish.
In a 20g you don't want more than 2 inches depth overall, meaning when spread evenly, for fine gravel; sand is probably better at 1.5 inches. You can build this up a bit more in the back if larger plants need it.