Is there a cheap way of supplying supplimentary light

[nicebutdim]

As the days are now quite short and temps are not too bad the problem is the low light level.I have used metal halide in the past but it is quite dear to run,not even sure how many hours a day it needs to run.Does anyone have any idea how much a 175 watt halide light would cost for say 12 hours a day.Would a fish tank grow light be good enough,even they are complicated to understand between bright light and the red tinged colour available.

[AndyC]

I think electricity costs roughly 10p per Kilowatt hour. Therefore running a 175 watt bulb for 12 hours will cost 175/1000 * 10 * 12 = 21pence.
I use gro-light flourescent tubes in my heat/light box. The only light source is an 18watt tube for a box with floor area of 600mm x 1200mm. I keep the light on a timer for 12 hours a day and everything inside stays healthy green for the winter.

[Dave Brown]

You also have to have the right kind of light for plants. tungsten filiment lamps are not that good. Mercury lamps are better giving a bluer, more cross spectrum light. Lots of professional growers use sodium lights, but it is almost a degree subject knowing what type of light gives best results. Reder lights promote flowering etc.

I use mirrors to reflect/double natural light Plants against a wall with mirrors behind them grow more upright