As I never saw a Magnum filter, or know about gallons etc etc. I ill have to stick to general principles, without any name.
I use both push and pull filters - push meaning the pump is in the tank, and the filter itself follows. I've had a lot of problems with sand in this arrangement, but putting the pump on a square stone - I use garden tiles 30 * 30 cm - or 1 foot aquare. These are placed 10 cm from the floor (or 4 inches) As long as my cichlids don't spit sand on the tile, the amond of sand displaced is manageble.
I have 2 kinds of pull filters - the commercial ones (with e veryting aoutside the tank) and others. The sucktion for the commercial tanks is some 10 cm above the sand. In 3 months perhaps a teacup of sand gets into the pot
The last kind of filters - indide pull filters, are based on foam mattrasses, but they all have a antrance barrier of 5 cm (or 2 inches) The water goes horisontally from the entrance part to the clear water part, through the said mattrasses. In the cler water part I have a pump, pumping the water out. I never saw any sand in this clear water part
So, by putting some distance (=gravity) between the pump entrance and the sand, the problems are manageble