Well i had a eheim 1048 pump.. that was
158 U.S. gal./h.
it broke.. and i went back to the shop.. switched it to a 1250 pump wich has
316 U.S. gal./h.
all this with 3/8" tubing.. didnt notice any difference at all.. so about 150 Gallons / H should be enough i suppose..
and a question from me to the more pro users on this forum :P should i switch to 1/2" tubing instead.. and get a maze2 with 1/2" fittings? would that improve cooling?