Hello and thank you for your inquiry.
As far as your current fixture, that certainly isn't too much light but as many companies are no longer making Power Compact (PC) bulbs you may find it harder and harder to purchase proper replacement bulbs.
As far as T5 fixtures, I would recommend either a 4 or 6 bulb fixture. A 4 bulb fixture will be for some SPS corals (may need to keep them towards the mid to upper parts of the tank) and most LPS and soft corals. A 6 bulb fixture will allow you to keep most corals at any level without much trouble (assuming other tank parameters are good).
If there is anything else we can do for you please let us know.
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