Quite possibly, but it depends a little....try to define those percentages in terms of lux or PAR.
If you don't have a meter, start with a $free lux meter app for your smartphone like "galactica luxmeter" for IOS. (There are many options for both phone platforms...not all are equal, so double check your first samples here or PM me to make sure it's working.)
Once you have an idea how much light you're throwing at your tank, you can consider the concept of "peak sun hours" (PSH). It's harder to explain than to show with someone else's diagram:
Direct Sunlight over an equatorial day is about 1000 watts/m2 (also 100,000 lux, or 2000 PAR)...which I understand to equal about 5 PSH.
In other words, 5 hours at "Peak" (100,000 lux) would be energetically equivalent to a whole 12-hour tropical day that included the complete sunrise-to-sunset cycle.
So if your lights are as bright as the source (or depth) you're trying to emulate, all you may need is 5-6 hours of ON time.
If you want to be nerdy and experimental, there are solar power websites
like the one where I stole that graph where you can look up the peak power and PSH of different locales. If you can back-figure your light's power to watts per square meter of your tank, you should be able to find a locale with a similar peak power and therefor be able to look up its PSH....aka how long you should leave your lights on.
(I think I kinda worded some of that wrong but the gist is right....read that link for the right details tho pls.)
