I'm in two minds what to do with my 60 litre ARC, I'm taking out the 24W lamp and was fitting 6 x 3W LEDs in a DIY unit. The reason for this is I have some large root in there which casts a shadow on my substrate so some of the HC won't spread under it, with the LEDs I'll get a more even spread of light. But, I don't know whether to add 6 or 8 LEDs? I know with 6 it will be 18W but it will be more intense light but still I wonder if I should make it 8? Andy has 15 over his 125 litre I believe so do you think it will be ok, I have quite good flow and dose CO2 and ferts but I dont want a tank full of algae.