How far above...?

[Retired_AF]

I am still in the planning stage of setting up my 90-gallon saltwater tank, delayed due to a stupid accident involving me, a ladder and a 7-foot fall causing bruised ribs and a separated shoulder.

Anyway, I was thinking about the lighting and possibly going with this:
48" ADV PLUS Aquarium Metal Halide 716W Reef Fish Fan | eBay

I see that it comes with 3" legs, but this seems like it would be too close to the water. I plan to use glass plating on top but was wondering if this would just cause the fish to parboil.

My question is: How far above the water should I hang these lights to avoid excess heat yet still be usable? The tank is 48"w x 13"d x 33"h with plans being to start as FOWLR then convert to reef, so I know I will need the MH bulbs to light the bottom adequately. I just want to see the fish, not boil them.

 

[CleverBs]

i think you would be fine as long as the tank isnt covered with glass, its not good to cover the tank with glass because it does not allow proper gass exchange from the water to the air. also by not having a glass cover you wont heat the water up nearly as much.

 

[ccCapt]

When I ran metal halides I had them about 10" above the water.

 

[Retired_AF]

i think you would be fine as long as the tank isnt covered with glass, its not good to cover the tank with glass because it does not allow proper gass exchange from the water to the air. also by not having a glass cover you wont heat the water up nearly as much.

Interesting about the gas exchange... hadnt thought about that... I was thinking more about keeping the fish inside the tank instead of them doing some carpet surfing...

 

[Retired_AF]

When I ran metal halides I had them about 10" above the water.

Yeah, I was thinking somewhere at or around 12" but didnt want the light to spread out so much as to be wasted.

 

[CleverBs]

Interesting about the gas exchange... hadnt thought about that... I was thinking more about keeping the fish inside the tank instead of them doing some carpet surfing...

use egg crate or screen in you have a overflow.

 

[Retired_AF]

use egg crate or screen in you have a overflow.

Egg crate may be an option. I have an overflow, but the return will be over the back. I suppose I can cut out a small section for that. Screen is possible but may be impractical without some type of framing, which I donr have.