New Tank

[lorano]

Hi, i am about to set up a new tank for my 4 female bettas. Im going away for the summer so my platties will also be living with them(they are like pygmy or something) and also my endlers is this ok? Its a 20 gal tank and i was wondering if that was enough room for all of them and if i can use sand instead of gravel. If i do sand instead of gravel is there something special i need to do? kinda new to this al my other tanks are small 5gal. any suggestions would be appreciated =D