distance between lights and water

[maui]

i'm setting up a new tank with some plants and lights, its a total DIY project I'm currently making a stand to hold my light fixture and i'm wondering how far should the lights be from the surface of the water?
my tanks also have glass lids - which i leave slightly open, are glass lids a problem when it comes to light? do they limit the amout out light that will reach the plants?
i've heard that keeping lights more then 22' from the bottom of the tank would require more intense lighting - does this mean that i can keep my lights a max of 10' from the top of my 12' tank? i was thinking of having them 5' above the top of the tank... would this be alright?
any help would be awesome - thanks in advance.

 

[Silly me]

try to get them as close to the water as safely possible.

5' might be ok but the closer the better

 

[fraservet]

glass coverslips will reduce the amount of light, but if they are kept very clean, this will be minimised.

the closer the light is to the tank the better - try to get waterproof caps for the ends if possible.

the distances you have quoted relate to depth of water
10" of water reduces the intensity of the light a lot more than 10" of air does

 

[Dubby]

In my tank they are about 2in above the water line. I have waterproof endcaps but no other cover. The only drawback is that it means I have to clean the tubes of limescale buildup once every couple of weeks.

 

[maui]

thanks for all the info folks.
i ended up setting them approx 5' from the surface of the water, i hope this works out alright or else i will have to so some serious redesigning of my lighing system.

 

[lilaliend]

Hi,
Just wanted to give my 2 cents, even though you seemeds to have finished your set-up.

I have a large 75gl tank, with a dual bulb, 48" shop light fixture hanging from the ceiling overtop of it. Total distance from the very bottom is about 34"-36", over 50% more then that 22" max. I have one colormax bulb and one nutrigrow plant bulb. Picture

They work great. Plants are VERY hardy in my tank and grow very rapidly. The first time I got a couple bunches of anarchis, the grew about 3 inches within the first day. I recently purchased some dwarf red lilies and set the bulbs at the very bottom, and in 2 days they all had stems with 2-3 leaves on them.

I don't think you have to much to worry about.