24 hour lighting for new planted tank

Rob1eddy

AC Members
Sep 4, 2005
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South Carolina
Just set up a 150 that is heavily planted with swords. There are no fish in the tank yet. Would you keep the lights on 24/7 to get them started or would you run 12 on and 12 off.

Thanks
 
I think plants prefer a natural cycle. I'd stick with 12 on and 12 off.
 
Just remember plants need to rest at night, so a 12/12 or a 10on/14off cycle is required. During night the plant is in respiration which allows stored energy to be released into the plants cells, if this does not happen the plant could simply wear itself out and do major damage, not to mention the algae growth you might get with a 24hr light cycle.
 
I question that plants will "wear out" under 24/7 lighting as I use this on some veggie filters without any problems. But I do prefer for my displays with fish to have timed 12/12 light/dark cycles.
 
Plants require darkness as much as light. During the light cycle, they respirate with CO2. During the night, with O2. You could probably run the lights 24 hours and still have the plants grow and live, but assuming your plan is to make them really really grow, leaving the lights on 24 hours would probably slow the growth of the plants if anything.
 
Sorry, but I disagree with that post. In my tanks, the 24 lighted plants grow more strongly than do the same plants under only 12 hours of light. Do you have any reference for plants requiring darkness? I would be interested.
 
Sorry, but I disagree with that post. In my tanks, the 24 lighted plants grow more strongly than do the same plants under only 12 hours of light. Do you have any reference for plants requiring darkness? I would be interested.

well, not sure that plants require darkness per se, but they cannot photosynthesize constantly without some sort of side effects...as I understand it photosynthesis and respiration occur together, when the lights go out, respiration continues and oxygen is absorbed and acts as fuel to release energy from the plants storage...hence the plant is resting and readying itself for the next days photo period...perhaps some plants have adapted to 24hr photo period just not sure where that would occur in nature...what type of plants are you talking about?
 
Plants in photsynthesis produce O2 in quantities beyond their requirements, releasing excess into the surroundings. During darkness they do not produce O2, so must absorb some from the surrondings to meet their respiratory needs, but their output per 24 hour period exceeds their usage during the same period. That much is fact and well known. I would like your references for the requirement for "hence the plant is resting and readying itself for the next days photo period..." as I have no information on that at all, and remain unconvinced of its reality.

The aquatic plants I have used successfully under 24/7 light include Val, Hygrophila difformis, Anacharis, Aponogeton species and hybrids, and Java Moss.

I neither said nor implied that it occurs in nature, as it does not in the natural environments of any tropical plants (only around and beyond the Arctic and Antarctic circles), but then neither do glass boxes with artificial lights occur in nature.
 
well, hey, maybe your right due to the fact that our aquarium lights pale in comparison to the sun and many of our typical aquatic plants will never reach the straining point I was talking about. But if you must have a quote, refer to page 14 and 17 of Aquarium Plants by Peter Hiscock which talks about problems with a 24hr photo period and the importance of respiration-only time.
 
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Give your plants some darkness! However, in the lab we often give plants 24 hours of light for short periods of time to grow them faster, so they will do fine for a period of time. If they're subjected to constant light for too long they will slowly stress and their circadian clocks will be completely out of whack. Not good for the long run. But I see no harm in leaving the lights on constantly at first to help them get established.
 
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