Hey guys i was wondering about changing my gravel!!!... i was wondering if there was a "safe" way of doing it... what if i dont COMPLETELY change all of my gravel but say, take half out and replace with new gravel... leaving approx 50% new and 50% old gravel... reason for changing, is i would like a not so bright gravel color and moving to a soft neutral color or black! THANKSM FOR THE INPUT!