Mine is a 55, I have one 1200 with kit. Another PH is pointing behind the rock, but it is weak, bought it off a friend and I don't even know how much power it has! The MJ I have about 1/3 of the way up the side of the tank pointing towards the middle of the surface. It causes a lot of ripples in the surface water which will help with gas exchange but hurt with evaporation. A double edged sword, but I feel I am getting the better of the two sides. I would think it would work for a 75 if it works in my 55, but if it doesn't work it just doesn't work!! I'll post a pic of the placement of mine if you would like... _________ 55 gallon slowly growing reef aquarium, 85 lbs. live rock, 2 1/2" sandbed, 1 False Percula Clown, 1 Sixline Wrasse, 1 Mandarin Goby, Tetratec PF500 filter, 2 110 watt URI Super Actinic VHO actinics, 2 250 watt metal halides with Reef Optix 2 reflectors powered by Blue Wave 3 ballast, born 1/3/08 My Tank Thread My Tank Video  |