New to MH

[fuzzybob4]

I've been running T5HO lights foe the past 8 year, I just got MH yesterday,to run over my 40 gallon aquarium.
The tank only can hold 20 gallons of water, at 8 inches. The tank is sitting no the floor.
how high should I have my lights?
What's the best corals to place in the tank to have them grow as well as giving them color?
The lights are 2x 150 W and 2 x actinic 54w
I'm sure that I will have more latter on.

[Big_Pun]

light is over kill, more power isnt always the answer, it wont make corals grow faster. you dont want to burn coral, par meter would prob help. its not impossible but you will need to mount it about 1 foot above maybe more and waste a lot of light spilling into room. thought you ran a store out your garage shouldn't you know basic lighting for tanks at this point?

[fuzzybob4]

I've used T5HO and LEDs but I have not used MH just because they give off a lot of heat.

[Zack]

Way too much light for such a shallow tank..

[fuzzybob4]

Even if the light is about 2-3 feet above the water level?

[Zack]

Why can't you fill the tank up? Heck why not just run one of the halides?

[fuzzybob4]

The tank was an old turtle tank, so it has a side that is cut in half and I got the tank for free, so was like ill use it as a frag tank, and that's kinda what I was thinking was just to run one. One is more over the tank thn the other one is, so it's brighter on one end of the 36" compared to the other side if only one of the MH are one.