Tell me why I can't use MH/T5 lighting systems designed for hydroponics?

[pastout]

i have a sunlight supply t5 48 inch 8 bulb fixture that was mounted 1 foot almost above the water and it had tons of light comeing from it and i didnt find the reflectors inferior at all even compared to the tek fixtures ecspecialy because every bulb has an individual reflector also. this was on a 90 gallon

[spreerider]

the reflectors in hydroponics can be just as good as the ones for tanks, hydro guys are just as worried about efficiency as we are, its just they have alot more cheap low quality ones than we do for aquariums.
you get what you pay for no matter where you shop but hydro guys dont pay the excess premium that we aquariests pay for our specialty equipment.
You can save a bit of money buying a hydro one that is still good quality (dont buy a $20 reflector and expect it to work as good as a $300 one)
but they have a larger market where people usually buy multiple units, so the costs go down due to volume.
Best way is to get some high reflective aluminum and make your own, you can buy a sheet of polished aluminum for fairly cheap and slam a reflector together and copy whatever design works best for you,
or do what i did and buy a cheaper hydro reflector and modifiy it to fit and preform better on a tank shape.