yep, just scoop out the gravel and replace it with sand.
In that aquarium I used playsand from Walmart. That will work, just make sure you rinse it really well before you put it in your aquarium. And when you put the sand in the aquarium be careful to not just pour it in. I use to take a cup full of sand and water and gently dump it it along the bottom of the aquarium. The sand wont settle right away and will cloud pretty bad if you don't geti t as close to the bottom as possible.
In that aquarium I used playsand from Walmart. That will work, just make sure you rinse it really well before you put it in your aquarium. And when you put the sand in the aquarium be careful to not just pour it in. I use to take a cup full of sand and water and gently dump it it along the bottom of the aquarium. The sand wont settle right away and will cloud pretty bad if you don't geti t as close to the bottom as possible.