I am looking to get a sicce syncra sdc return pump. I am unsure which size to go with as my tank is a 40 display cube with a 20 gal sump below. I am between the 3.0 (260-800gph) and 6.0 (530-1450gph). Head height is 4'6". Right now I am currently using a jebao 3000 which is 3000l/h. I feel like I could definitely use more flow in certain areas but at the same time am worried that the 6.0 may be pushing it too much. If anyone by chance has these exact specs let me know your experience. If you have a similar size please let me know what you think.