# LED photo period control - so many options



## peter09 (Dec 2, 2011)

Hi,
I have a 300l planted tank which is lit by three TMC Growbeam tiles. So far (18 months) and after initial problems things are good, I have the best tank I have ever had (although still some problems with red plants  ).

These tiles are controlled by a TMC Controller that allows me the following variables:


Max and Min % lighting 0-100 %
Ramp up time in minutes of 0 to more than 4 hours
Ramp down time in minutes of 0 to more than four hours

There is a little bit more but this is immaterial to this thread.

Recently I changed my light schedule ( I increased it by an hour) to 9 hours max plus a 1 hour sunrise/sunset ramp and I am noticing a slight outpreak of green hair algae. This coincides with a change in feeding and a good prune, so it might be coincidence 

So, on considering whether to reduce my photoperiod I began to wonder wether I should increase the ramp up / ramp down times rather than reduce my max light output (presently 100%).

So, for instance I could change things to a 3 hour ramp up and down time (giving me a 4 hour max period) leaving the max output at 100%.

In some ways this may be more natural, in that, although sunrise is a matter of say 15 minutes, I would guess the attainment of max sunlight will be in hours.

I would be interested to hear of anyone who has used ramp time as algae control and any comments anyone may have on this idea.


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## Jane in Upton (Aug 10, 2005)

There was a mention of the "Emerson Effect" on this thread here (post #3)

http://www.aquaticplantcentral.com/forumapc/lighting/86514-why-my-favorite-german-bulb-may.html

is this what you're thinking..... to achieve (or avoid) this idea of quickly closing down photosynthesis at "sunset", so its not happening when the rate is not most effective?

My guess would be that if you increased the duration of your max output, the algae could be a result of exceeding the availability of CO2 and/or nutrients, and the plants photosynthesis rate, allowing the advantage to go back to the algae. But, with 3 variables you mentioned, its just a guess.

Algae can utilize very low light levels, so I'd be dubious about extending the ramp up/down period of time when the plants are not at their most productive, but algae is happily gobbling up all the nutrients before the higher plants get going.

Just a thought.
-Jane


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