Light Spacing

I'm picking up a complete 20 gallon reef setup. It is a small upgrade from my 6 gallon nano (JBJ). Since the JBJ was compact I had little to do with the setup. Almost everything was done for me. When I get the tank home today I'll need to mount the metal halide light.

My question is how far from the tank should the light sit? It does not sit on top of the tank, but hangs above it. Can it be too close?

My guess is that if it is too close the tank water will heat up and if it is too far away I'd miss out on part of the weaker spectrum. Will any of the corals or inverts be affected by it being too close? Can they get too much intense lighting?

Once I get it all I'll put the exact hardware up here with some pics.

 

Well it all depends on the wattage. How many watts are the bulbs? How many? On the average, the lights should "hang" over the tank at least 6".

 

It is best to keep a gap between the air/surface interface(top of tank) to allow for heat generated from the halide bulb to disipate, cutting down on the temperature of your water from elevating . It also reduces the chances of salt creep from accumulating on your protective glass lens housing the halide bulb.
6 inches a lunatik 69 pointed out is a good distance, and it doesn't really effect your tank with regards to light spectrum, PAR, PUR and wattage.

 

My 5.5 gal has about a 6inch gap like luna said.. I started higher and adjusted my heighth with the temp. If too much light too quick corals can bleach... be careful....

 

It is a pendant MH and I have it at about 7-8 inches off right now. I'll be watching the temp on it today once the setup is complete.

The water is a gross yellow. She told me the (what she called) encrusting gorgonian gives off brown powder in the water when he gets stressed and that is why. It looks like the bottom is covered in silt there is so much.

There is a huge bristle worm infestation. Inches long and real thick. They are under every rock.

I already rescued the pink skunk clown and put it in my nano for now until I get the water cleaned up in the other tank. The royal gramma didn't survive their trip to bring me the tank.

I am about to setup the skimmer. It is a seaclone 100. I know most of you don't care for that skimmer, but it came with the setup.

Any ideas on how to clean this tank up?

 

Do you run any carbon?? Not continous, but for like 3 days every couple of weeks??????? Sorry for the loss of your royal gramma... I miss mine also...

 

She had no filtration at all in her tank. Just a PH and the skimmer. There is not nearly enough LR to avoid a filter. I'm not sure how it lasted this long. She told me it has been up for 3 years since her friend gave it to her.

 

"The water is a gross yellow. She told me the (what she called) encrusting gorgonian gives off brown powder in the water when he gets stressed and that is why."
That could be the reason or it could be an excess of dissolved organics known as "Glebstoff".
Carbon regimine will help to diminish this, along with efficient skimming and a partial water change!

 

More info....

The MH light is a single mogul based pendant. 175 W bulb. The bulb can be found here.

Does anyone know how trhis bulb performs or if it is even a good lamp for a reef tank?

 

Not sure how good it is.. Newb thinking like me would think 175 watts of MH over 20 gal wouldn't hurt.....