i got 2 croc’s, 1 is 12 inch’s the other is 14 inches. i just made a water tank 10 ft x 4 ft and 2 ft depth (water is only going to be 1 ft high ). there is goin to be a basking spot 4ft x 2ft on one corner, and a island in the middle 2ft x 18 inchs. what should the substrats be. i was thinking marble’s and stone plates. anything but sand. it’s goin to be kept in the back garden and its hot here (pakistan). also what kind of filter system and pumps are needed.thankz in advance....