Lighting question?

[kodak]

I wanted to know the optimal tank depth for keeping softies using a Coralife SP 4x 65W 10000K light fixture.. I plan on using 4x 10000K bulbs in this fixture and will have another fixture running 2 actinic bulbs.

I will be keeping mostly zoas, mushrooms, palys and other stuff at around the same level of difficulty..

The tank foot print as far as length and width goes will be 4' x 18"

Thank you..