Not Enough Light On Large Tank

[Rodders]

I surrently have 1.6wpg on my tank. 660 usable litres.
Still getting diatom problems so I guess the plants just arnt out doing the algea.
If I put another 58W tube in this will give me 2WPG.
But some people say that on larger tanks the WPG isnt so important.

What do you think

Also whats the dif in T8 and T5???

 

[jimbooo]

T5 has a smaller diameter tube. much brighter (and hotter) for the equivelent length.

how deep is the tank? my cube is 2 foot deep with 1.3WPG. does rather well i must say. have you got co2 on it?

 

[Rodders]

Co2, ferts.
Its 2 foot deep.
I also have dark sides, just lookslike it could do with more light for more than one reason.