New to having a tank this size, 20g aio to a 50g, never plumbed a tank before, bought it from someone quitting the hobby. It's a durso overflow, thinking about drilling another hole and making it a herbie perhaps, is there enough space to do the conversion and is it too much of a risk to drill near the edge? The overflow dimensions are (7.5''L x 4.35''W x 18.75''T) the return is 1/2'', and the drain is 1''. Thanks for all and any future info!