Fluorescent lamp height from water surface?

[hadjici2]

Hello people,

how much distance would you leave between 3 25 watt fluorescent lamps and a 120 litre tank?

I don't have any fish or shrimp yet and I don't intened to if the temperature remains at 35 degrees celcius. I only have plants...

Thanks in advance....

 

[jimbooo]

the closer the better, mine are about 25mm above the surface.