I had a lot of light already but I changed 1x 125W Mercuryvapour for 2x 80W T5 just a few weeks ago. There still is 325W mercuryvapour and 250W MH.
The elctricity bill is counterbalanced by not having to heat the room during winter as much (now how's that for an argument). He it's a hobby, it may cost some money, I don't drink, don't smoke, don't have an expensive car, I do play golf but have a nice job also.
Not almost, it's excactly 1500 liters, (200x80/120x75 cm), and therse app 350 lit biological filter next and under it.