retrofitting 36 inch coralife t5 for leds

Have an old t5 coralife 4 bulb 36 inch unit for my 40 gal breeder

Its actually a pretty good light, but current set of t5s are getting near 12 months old

I have a pretty complete led setup that I bought from rapidled a while ago

Would be a good fit for the heatsink to go into body of the unit

I would prefer leds, as Im going into sps

Have two questions, however



1 I would like the unit to sit on tank rim, dont really have a ceiling to hang a in that location. leds will be 4 inches from water, covered with a splash guard

Is that too close for safety/heat etc?



2 Are any lenses required if its that close to water?