07-08-2009, 09:27 AM
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Originally Posted by saulat
This may be off topic a bit from my original post. Should I post another thread? My question is that now that my time is here should I have the lights on for 8 hours, off 2, and then on 4? Just curious, algea is not a concern now so what is best for my plants?? 4 T5 lights, 2 6700k & 2 freshwater, 28 watt each for 112 total watts. 55 gallon tank. Plants
and of course the original reason for the post, stargrass perhaps
I have often read about staggered periods of light, especially as a means of combatting algae. To refresh my memory I have turned to Peter Hiscock's recent book and here (in his words since I can't say it as well) is what he says:
Most tropical regions receive roughly 12 hours of daylight, with 10 hours of strong daylight and 10 hours of complete darkness and this varies little throughout the year. It is important to make sure that plants in the aquarium receive a similar amount of light on a regular basis. ... It is important that aquarium plants receive periods of complete darkness. During this time, plants stop photosynthesizing but continue to respire, so a dark period can be considered a period of "rest" for the plants' biological functions. Plants are able to regulate the rate of photosynthesis relatively easily, and quickly respond to changes in light conditions. Algae are not so biologically advanced and need a long and relatively uninterupted period of light to function properly. it is possible to combat algae in the aquarium by controlling the intensity and period of lighting and creating a "siesta" period. This is a perid of darkness that interrupts the normal day/night light cycle. If the aquarium receives 5-6 hours of lighting followed by 2-3 hours of darkness and then another 5-6 hours of light, the plants will be relatively unaffected and receive enough light throughout the day, but algae growth rates will be significantly reduced and may even start to die back.
Elsewhere Hiscock mentions 10-14 hours per day of adequate light to satisfy the photosynthesis requirement, so this can be continuous or divided as above. I have my lights on for 13 hours, and in the past have had them on for 15 hours each day (had a different personal schedule then); with my minimal light (1 watt full spectrum per gallon), no additional CO2 and regular liquid fertilizer, this has worked for 15 years. Algae is generally within reasonable limits, although I do see periodic bursts of hair algae or brush algae [these are the worst] brought on by some factor; I think next time I will try Hiscock's siesta approach.