Indoor lighting for ficus and serissa questions

Hello all. I know there are huge discussions on light sources and what to use. I will try to limit the discuss to fluorescent fixtures. I have a indoor set up for some ficus and serissa I may extend the set up to include something else later. The table is near a south facing window and the table top is 4' by 4'. I have two 4' dual bulb fluorescent fixtures over them. For the past 2 years the plants have lived but not thrived much.

My question is using the 4' standard fixtures I have, what bulbs should I be using? I have 2 cool white and 2 sun (ge bulb name) rated bulbs. Do I need another type? more lights? I need to keep the same 4'x4' stand

A couple of things. Fluorescent bulbs are only at peak output for about 6 months, so they should be changed at least every season, also since they do burn fairly cool they shouid almost touch the foliage, if you have different size plants arrange things so the smaller plants are elevated toward the bulbs.
Plants are never going to thrive under lights compared to the sun. You can also put reflectors on three sides of the set up, al foil will work.