You must replace the stock bulb(s) with a higher intensity bulb, maybe a powerglo, coralife trichromatic 6500k, coralife 10k, etc. The bulb you choose MUST have a very strong blue peak at around 420 nm or so. I would personally use Coralife 50/50s. There are a number of drawbacks to eclipses though. They cover the ENTIRE top of the tank so you can't hang anything on the back without cutting a space in the hood. They cannot be used with VHO or PC unless you retrofit, which can be a pain. The biowheel can potentially cause nitrate problems if you don't have enough LR, caulerpa, and skimming.
That having been said, the best LFS in the area has a 6 gallon eclipse reef. They replaced the crappy eclipse bulb with a powerglo. There are shrooms and other soft corals in there, and they seem to be doing ok. Two damsels, one big and one small, inhabit the tank. I wouldn't do this because the lighting is barely marginally adequate for corals. I will use 4x96 PC over a 55.