Tank temp update;
Since adding the 2 4" temp sensitive Ice Cap fans :
The fans are set to turn on when the lights first come on in the am and turn off when they are out, just like my old 3" fans.
In the morning before the lights and fan are on the tank temps are 80.8 at 6 am , then after 6 am the VHO come on with the fans, then at 7am the MH come on. At 8:30 am with the MH on 1 1/2 hours the tank temp is 80.4 , when I used the smaller fans the temp would be 81.5 by this time.
I am not home in the day to see what temp the tank stablizes at , but I will see on sunday when I will be home when the MH turn off. It looks like the Ice Cap fans are more then enough for the two 175w MH so far.