# Low/long or high/short photoperiod



## IntotheWRX (May 13, 2016)

aja31 said:


> Is there any research or experience in which is better for plants? Is it better to have a lower overall intensity light on for a long time or a higher intensity light on for a shorter time.
> 
> I'm trying to figure out my photoperiod and I'm not sure if I should keep the intensity lower and then ramp up quickly for a few hours. Or if I should ramp up slowly but have a decent par reading for the whole day.
> 
> Anyone try both and prefer one? Is there an established study of this somewhere?


i have a medium-high light on my tank so i do a 3hr light period, rest for 5 hours and then another 4hr light period. The plants do appreciate the rest as they restock up on nutrients.


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## jeffkrol (Jun 5, 2013)

aja31 said:


> Anyone try both and prefer one? Is there an established study of this somewhere?


studies I've seen basically conclude it is photon accumulation that matters the most, up until the saturation point..
Considering most aquatic plants are really "low light" (compared to corn ect.) you can probably reach saturation, though not easily..

Sooo basically no difference as long as long enough to get the photosynthetic system working at full 
then again light is only one component..SO too much light and not enough CO2 would favor lower light levels for longer period of time.. (natural atmospheric replacement..)
OR not enough nutrients will cause a slow down or stoppage..
https://www.google.com/url?sa=t&rct...4VdFrDA4OP68qD2qg&sig2=LrXx6Awm25AQw9cRCQDaGw

Sooo if CO2 isn't limiting, and nutrients aren't limiting it shouldn't make much of a difference..


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## theatermusic87 (Jun 22, 2014)

If we use nature as a guide. Long and high in the summer, lower and shorter in the winter. The changes between them (along with temperature) trigger things like flowering, growth and seed production.

This isn't exactly the same as we get in aquariums, esp with more of our plant species being tropical and sub tropical species that have less pronounced seasonal changes. Also the amount of light available in our aquariums is tiny vs outdoors in ponds and lakes. So I highly doubt we can over saturate most of the plants we grow in all but the highest of high light tanks (though I think full spectrum plays more of a role than most give credit to).

Honestly I think as long as light level (not co2 or nutrients) is the limiting factor and plants get no more than 50-60% (roughly 12-14 hours) per day you should be fine.


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