I have playsand as my substrate in my 55 gallon with lots of different plants. don't have a problem with uprooting and it's a very full tank of guppies, cories, plecos, loaches, a betta, shrimp and a ton of different snails.
Based on the pic of the bowfront I would say you don't have a deep enough substrate for the roots to really dig in. I have mine about 3 inches deep.