switch from regular plant fluoros to T5?

[RandiRae]

I have a 75 gallon aquarium as my orchid home for my catts, mini catts, bulbo, and misc. Plants are growing but never bloom. I'm pretty confident my watering/humidity is ok..so I'm looking at my lighting. This subject has always made my head spin but it's time to tackle it. The height of the tank plus canopy is about 18-20". Right now I have 8-fluorescent bulbs 'for plants'. The plants are about 6-9" from the lights.

I don't have a light meter....are the lights anywhere near where they should be?

Should I switch to T5's? And will they fit into my existing general fluorescent light fixtures?

How close should they be (I prefer inches, but if need be i'll get a light meter to understand the whole lumen/foot candle stuff)?

Thanks!