Height

[demonmagus]

If a tank is 18 inches high rather then 15 inches, will this drastically change the lighitng needed?

 

[Siamese Fighter05]

I think PC's can penetrate up to 12" of water.
T5HO can go to about 15"
For 18" you will need a 150w MH

 

[steelhealr]

Agreed...18-20" and lighting at the bottom gets affected. SH