My situation is that I have a 75 gallon tank that im planning on planting. I used the beamworks led mentioned above on a 55 gallon and was not getting nearly enough PAR. In your oppinion would you say a t5ho would be the best route for my scenario?
Well it all depends on your goals for the tank, your experience level, and what kind of plants you want to keep.
Reflectors make a big difference on fluorescents. Lights that have individual reflectors for each bulb are a lot brighter than ones that use a single reflector for all the bulbs.
Assuming you get a unit with good reflectors, a four bulb unit will need to be raised 12"-16" above the surface of a 75 gal, else it'll be way too much light.
With the fixture just hanging in mid air, a foot or two above the tank, there's going to be a lot of light spilling out into the room, and into your eyes. Some folks dont mind this. I do, which is why I use ancillary panels across the front of all my tanks. So that is something to consider as well.
I had a four bulb unit on a 75, about 9" above the surface. Par at the sub around 120. Which is way too much for most folks, and way more than any plant needs.
Currently have this light
about 6" above a 50 gal, which is a short 55. Par at the sub around 90. That's still high light but a lot more manageable.
The more light you have, the faster everything moves. Both good things and bad. If this is your first time with high light, 60-70 par would be a good range to shoot for. That's plenty for most anything, and will be a lot more manageable than higher levels.
If you go with T5HOs, you'll probably want a four bulb unit to have good coverage front to back, and more bulb options. Use one or two 6500Ks and the rest red/pink types.
Just plan on raising the light a good bit off the surface, 12" -16" like I said before. (Id start at 16")
And it should go without saying that CO2 is a must.
Here's a thread on bulbs and a few journal links to folks using T5HOs. Might give you some additional food for thought.
A Thread For T5HO Bulb Comparisons
Clint's 75 Gallon. High Tech Project Update 5/5/17
My old 75 which started out with a two bulb unit, then switched to a four bulb around page 6 I think - A 75 Gallon Journey ->
My current 120 with a six bulb unit - http://www.plantedtank.net/forums/12...freestyle.html