Above or below the Aquarium Water Line? Power jet versus spraybar.

by Herbert
(Manassas, VA)

Folks, My brand new XP4 arrived yesterday. I intend to do the assembly today and begin operations tomorrow. My aquarium is freshwater 150 gallons. I will have under-gravel filtration in addition to the XP4. Should I place the XP4 outlet above or below the waterline? What are the advantages/disadvantages of a powerjet vis-a-vis a spraybar outlet (I was planning on spraybar.)? Must the spraybar outlet be horizontal?
A: Please contact the manfacturer or the dealer where you purchased the item if you need a quick answer to this question. We will also post this for others to comment.