Flow Question - 4 MP40 SPS Tank

[LAX Noob Reef]

So my 48x24x24 has 4 MP40, all 4 at 2 end of the tank. 2 at front end, and 2 at back end. My aquascape is kind of like 3 island type, so my question is this. Should I run at 100%, or reduce it to 75% or below. 75% already started to knock my sand around in to their own little hills, so I'm thinking of removing them this week since it's only about 2-3 inch sand bed during water change. Also 2 & 2 is sync, should I unsync it?

 

[Jbell370]

I have 4 running on my 6' tank, run reef crest 80% and 30 minutes of clean mode, seems to be plenty of flow and just enough to not create a sand storm.