It's not so much about getting the water cleaner as it is about lowering heat, electricity and noise. If 1x works equally as good as 4-10x.. then why buy and use pumps that pull all that extra electricity, cost and add that extra heat and noise? I have never heard of ANYONE using less than 3times there display volume as return to there sump. I know I have never dared lol. Anyone have any substantial evidence that 3x turnover or more is helping in any way or to the contrary that running lower would hurt?