Been a long time sence we had a lighting fact thread

[Shadetree]

Steve,

Not to be the pessimist but isn't there one variable that will skew all the results, water turbidity (Is that the right word?). Unless the water in the tank is approximately the same age, with the same amount of water changes, comparable skimming and equal carbon use, comparing different tanks is like comparing apples to oranges. The readings above the water will all be pretty accurate, or multiple setups on a single tank would be good, but the different tanks with different water quality would play with the numbers too much. Testing each system individually for long term drop off values is quite handy though. If carbon can "polish" the appearance of tank water to the naked eye, how much does that effect the light penetration?

Scott