My dry well, which was constructed of concrete cesspool block and was about 2 ½ ft in diameter by 5 ft deep, kept filling up with gray water ( laundry waste water only). I redirected the drain hose for a few months until the well was dried up and then dug up the old well (by hand) and enlarged the well to 4 ft wide by 6 ft deep. 

My question is may I use Septic-Scrub to maintain a well functioning dry well? If so, how much and how often should I treat the well? My soil is made up of tightly packed sand/rock/gravel (95%) and a littly clay (5%).

Thanks, 
Joe