where to drill holes

im going to be drilling a 210 gal tank and was wondering where the best place for the holes should be. What i was planning on doing was to drill the tank at the bottom and run pvc piping up to about an inch or so from the top of the tank. I have done this before but i had trouble with the pipe sucking in air and dealing with an ongoing gurgling effect. im now seeing that people are drilling the back of the tanks and running 90 degree elbows down to there sump. Is this the better way to go as far as being quieter. The pvc inlets are going to be 1 1/2".
 
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