4 or 6 bulb fixture for 40 gallon
 

I am setting up a 40 gallon, 36"x18"x16", reef tank. I am going to keep soft corals and LPS along with a few fish. Do you guys recommend I get a 4 bulb T5 fixture (156w), or a 6 bulb fixture (234w)? My only concern with the 6 bulb fixture is that I may have too much light. Not sure if that is possible as I have read mixed opinions about the topic.

Same tank I have, you should be fine with the 4 bulb if all you wanted to keep is soft and LPS, the tank is pretty shallow, would probably be pushing it if you wanted to try your hand at some SPS though. I have the 6 bulb fixture and keep a mixed soft/LPS/SPS without issue.

One other thing to note is the Tek Light fixture I have has two switches, one for the two outside bulbs and one for the 4 inside bulbs. You could always just start with that fixture (not "that much" more money) and if you are worried about too much light run only the middle 4 bulbs, that way you always have the option of "enabling" the other 2 lights in the future.

4 lamp unit is sufficient. 2 being white light and 2 being actinic for color rendering. 6 lamp unit if you plan on getting SPS.