Timing for a medium lighted, non CO2 tank

[wong1979]

About a year ago, I converted my high-lighted CO2ed tank to a non-CO2ed medium-lighted tank. Fast growing stemmed plants and carpet grass like APP and glosso were removed in place of ferns,moss,anubias and crypts.

My lighting timing is set automatically to on at 10am and off at 7pm. This is being carried out continuosly without fail for the past 1 year.

Current tank specs as follows:

Tank size: 60 X 40 X 50cm ( L X W X H )
Ave water depth: 35cm
Light from water surface: 15cm
Depth of sand: 8-9cm
Light wattage: 32 Watts PL
Temp: 26-28 C cooled by profantec cooling fan
Fertilisation: normal liquid daily, no base fert, occasional root tabs for lotus
Fauna: Averagely, 20 rasbora sized fish and 30 shrimps

Remnants from previous setup consist of 2 adult red tiger lotus and glosso. With these parameters, I expected both these plants to grow vertically upwards in search of more light. I trimmed of all the old leaves of my lotus and place them under the shade of my driftwood partially. A few strands of glosso were left untouched in a front corner of my tank. Keeping all parameters constant and without any trimming done on both, my forecast was wrong. The glosso was growing pretty slowly but nevertheless healthy. The strange thing was it grew horizontally, crept across the floor with hardly any gaps between the leaf and sand. The lotus that was adult, seem like baby lotus that remained low and bushy under partial shade.

The point I'm trying to put across here is that plants need to have light upon or after sunrise. I feel that it is not appropriate to start lighting up your tank, say in the afternoon till midnight. Or even worse, night till morning. The reason I think why 'light demanding' plants grow vertically is because of wrong lighting timing. Upon sunrise, they would wake up and start to harness any light energy where possible. If upon sensing not enough light, it starts to grow vertically in search of more light, therefore causing it to be stringy and ugly.

Anyone care to comment or debate on my theory?

Regards, Wong

[ms]

Your theory sounds logical but I could see some loop-holes.

The lights provide for your tank is artificial lights, simultating the environment. I do not think that plants have a biological clock that knows when it is sunrise or sunset - these are controlled by the timing of your artificial lights.

I guess my claim could be backed-up by the finding that humans who are trapped in caves does not live by the normal sunrise and sunset created by nature.
The person who is trapped in the cave live by his own day and night and not the outside world.

MS

[bclee]

My findings is that in non-CO2 tank, plants tends to grow shorter and more compact irregardless of light timing. My APP, Lobelia cardinalis, Hydrocotyle sibtorpiodes all grew more compact. The growth slowed and the internode length also shortened.

BC

[wong1979]

Your theory sounds logical but I could see some loop-holes.

The lights provide for your tank is artificial lights, simultating the environment. I do not think that plants have a biological clock that knows when it is sunrise or sunset - these are controlled by the timing of your artificial lights.

I guess my claim could be backed-up by the finding that humans who are trapped in caves does not live by the normal sunrise and sunset created by nature.
The person who is trapped in the cave live by his own day and night and not the outside world.

MS

All living things have a biological clock, its more on a molecular issue which I will not touch on because I'm no expert. Regarding your caveman theory, its the same as the principle of jet lag. Sunlight or any other lights are of course external factors relative to an enclosed enviroment. Let's assume that all the plants we get from LFS are accustomed to waking up after sunrise, say 9am and sleeps after 7pm. If you are to suddenly reverse the photoperiod, you will find that your plants are still sleeping even though the lights are on. However, I believed that you can tweak the biological clock of the plants gradually, over a period of say 1 month, in such a way that it can get used to it. Most of our aquariums in our house are exposed to daylight the moment sun rises. In order to carry out the tweaking of the biological clock, your tank should preferably be in a darkened room.

When I say that stemmed plants would probably grow stringy and ugly, it means that due to the biological clock factor, plants will start to carry out its 'work' when the time comes. Therefore, without light when its awakened, it does not grow as nice as before

I admit that my previous post was misleading in a sense that it made you think that plants know when it is sunrise or sunset. What I actually meant to put across is about the significance of the biological clock.