Reusing Sand Substrate
New here and new to the hobby. I just recently upgraded from a 10G to a 30G tank about 3 weeks ago. I switched from gravel in the 10G to Fluorite bottom with sand on top of the fluorite in my 30G. I don't really like how high the sand is at the front of the tank and how shallow it is at the back of the tank. I want to try and switch the 2 but I have read that distributing the sand can be very dangerous to the fish.
My question is, since my tank is only 3 weeks old is it still really dangerous to suck some of the sand out and then place it at the back of the tank? The reason I am thinking of doing it this way is because I have white sand and the fluorite is black. I am trying to keep the black bits under the sand as much as possible. Also I should mention it is a freshwater planted tank with hardy fish, all I can find info is on salt water tanks, that's mainly why I am asking.
Any help would be greatly appreciated! Thanks in advance!