How do you know how much light?

[PeteA]

Was just sat at work pondering (as you do), how do you know how much light your plants need in a tank? I know there isn't a going to be a scientific rule but was just curious how people gauged it

 

[thingymajig]

I would have thought its guaged on how much effort and time your willing to put in.

high light=lots of effort+more expense i.e co2/ferts/regular water changes
low light=less effort+less expense/no co2/fewer ferts/very few water changes..

hope this helps

cheers....