When you submerse, i'd say at least 5-6" above the surface. For DSM, experiment. if the top of the tank is hot to the touch during photoperiod peak, then raise it some more. depends on the type of bulb you have, ambient temp in the room, length of photoperiod, toughness of the plants, etc.
Okay man thanks for the help
Btw where did you say the links were?