quick light question: duration vs. intesity

[faded1004]

can you compensate for intensity by increasing light duration? for example...

if i have 250w can i get the corals more light by adding 4-5 more hours, rather then buying a 400w? can the increased duration give more light to the corals (sps mainly), or is it the intensity (distance and also wattage) that maters the most?

i always hear you have to ramp up when using new bulbs, and also when you get new corals... can you keep ramping it up?

so i have 2 x 250w, 4 x 85w t5, 2 x t12 vho... average running about 6-7 hours of white light and about 7-8 hours of actinic...

i am thinking about increasing to about 8-10 hours of white and 11 or more of actinic... will this help out with intensity or is it just better to get 400w 'ers...

i guess i want to mainly increase the light, feeling gracious to my corals... what do you guys think? will that make a difference?

aside: i didn't want to add another 250w although i have space for 2 more, i am focused on finishing my stand doors and little things that i don't want to upgrade lights right now... but i guess temporarily want increase the amount of light the corals get... also, i have no problems with algae, so i don't think the increased light will be bad...

[pjf]

Probably not. Dana Riddle demonstrated with a chlorophyll fluorometer that too much light will inhibit photosynthesis (http://www.advancedaquarist.com/issues/july2004/feature.htm). In fact, many SPS corals are photo-inhibited by the mid-day sun and depend on lesser morning and afternoon light for photosynthesis.

A dawn-dusk lighting scheme seems to be the best. MH lamps enable photosynthesis at the bottom of your tank and fluorescent lamps enable photosynthesis at the top of your tank when the MH is off.

[faded1004]

how many hours do you think is the split?

3 hours dawn, 3 hours noon, 3 hours dusk? with and extra hour of actinic in the beginnign and the end?

what do you guys think?

[reef / aholic]

interesting reading material

http://www.personal.psu.edu/sbj4/aquarium/articles/Photosynthesis.htm

http://www.science.uts.edu.au/des/StaffPages/PeterRalph/photosynthesis.html

[hahnmeister]

Its easier to have too little intensity and use a longer photoperiod than use more intensity and a shorter photoperiod. The pigments are like a sheild, and too much, no matter the duration, will penetrate and overheat the coral even if for not as long. You can however make up for having 'not quite enough' with a longer photoperiod... within reason. Running your lights more than 10-12 hours a day will have adverse effects on the corals anyways because just like you and I, the corals need sleep. They feed at night and do their calcium depositing (hard coral growth) at night, so dont deprive them.