Make sure you suppliment with artificial light. Sunlight will not be enough, and it is not very reliable from day to day. What light you use in addition to your tank depends on what you want to keep. I also use sunlight on my tank, it can give some effects and the coral lean toward it. It is pretty interesting to see it's behavior.
In what manner is the sunlight insufficient? Does it compare to 250W or 400W MH? I'm trying to avoid using such bulbs due to the varying, but always high cost of electricity here in California.
I expect to use MH in Winter when sunlight duration is shortest, and perhaps not bright enough. In Summer, however, I feel I should be able to use the sun most of the time. There is little sunlight variation here between March and October except for duration (I live in a semi-desert area). The aquarium will be in a large atrium that faces South.
