I have in the works a 130 Gallon Tall tank. It measures 36" deep and I was consideration building an Angel or Discus tank with it. I would like to grow some low light plants in it. Here's the question. Will plants grow under MH bulbs? I know I will need some powerful light to penetrate the 36" of water.  Any input is welcome.

if you can find a bulb with a low enough spectrum (somewhere around 6500-6700k)  you can easily grow freshwater plants under mh. just may need to toy around with the height of the light. the higher you have it the further the light will spread throughout the tank but i'm sure you've already thought of that

Thank's Buk.

Look into ADA halide bulbs. They are 8800k (or 8000k, I forget) which is wonderful.

Only problem is, you are probably still going to have to use pressurized CO2. That's still a lot of light.

Burks said :

Look into ADA halide bulbs. They are 8800k (or 8000k, I forget) which is wonderful.

Only problem is, you are probably still going to have to use pressurized CO2. That's still a lot of light.

Thank's Burks, I have a 20lb tank of Co2 and a power head to mix it, so that's no trouble. 

Rob I would suggest the Hortilux-blue bulb. They go down to 250 watts and are 6500K. I have seen these bulbs in action and the plant growth is amazing. co2 will be a must have. Ill include a link to the spec sheet for them. They sell on ebay for about $85 for a 250.

http://www.eyehortilux.com/tb/blue/EQS-N-52-78-57799.pdf

Also remember that in a tank that size, you're going to be using a lot of larger plants. They send their leaves up to where there's more light. If you want some grassy low cover plants, crypts might be the way to go.