Just for the record, I have an Emperor 280 & a Penguin 200 in my 46g bowfront- the same tank as the OP.
I do not have any problems with it sucking up sand. What I did do though, is by each of the filter tubes, I scooped away the sand from the bottom of the tank near the pickup tubes. That way the sand isnt as close to the vacuum force of the pump AND the fish kind of dig the little dips in the sand!
46 Gallon Bow F/W: 4 - Zebra Danio's, 2 - Red Platy's, 2 - lg. Silver Dollars, 1 - Pleco (4.5"), 1- Gourami, 1 - Cory Cat, 1 - mystery snail, 4 - Cherry Barbs, 1 - Black Molly