Light Timing

[uncle_catz]

I often read in this forum or others that hobbyist have the lights in their planted aquarium turned on for 10hrs a day, at least. I have my timer set for 4 hrs in the morning (8am to noon) and another 4hrs from 7 to 11pm. My plants seems ok and algae is under control. Am I doing it right? What is the recommended hours and when do you turn on the lights?

The tetras are afraid to come to the front and hid behind the plants whenever the lights are on. They would only come out when lights out. Not even feeding would entice them. But the rummies are ok. Is this behaviour normal?

[budak]

It's not advisable to do a double shift like yours. For one, plants photosynthesis takes time to reach an optimum peak that is enough to saturate the water with oxygen. Thus, in a typical 10 hour schedule, bubbling would normally occur in the early afternoon, unless so much CO2 is pumped in (wastefully) that bubbling happens sooner. Shutting down the light and turning on later only disrupts the process and the likely result is less than happy longer term growth. If you want to enjoy the tank after hours, just turn on the lights manually and off before you zzzz.

[Simon]

marc, mine tank doing fine from those timing.. its a matter of getting used to it. I supposed plants do the same..

[DEA]

simon, marcus is right
the siesta theory is that the shock and disruption of the photosynthetic cycle is more detrimental to the algae than the plants
but it does affect them to an extent

[Simon]

but surely a plant cant tell the diff btw day and nite time rite? so if we provide them light, they still work the same way?.. actually I supposed the 'siesta' thing doesnt affect the plants in some way but it affect algae growth too.. i think that was the main purpose of it?

[uncle_catz]

uh... a bit too deep for me.

From layman's point, CO2+light+nutrients = photosynthesis. If this process takes time, then how much time is needed? I've CO2 and nutrients but not sure how much light hours is needed. If 10hr/day is recommended and double shift is not advisable, when would be a good time to start the process?

[budak]

ok, it like this. Plants need time to warm up. In the night, they are actually consuming oxygen to produce CO2 (respiration). Photosynthesis is zero. So as the morning starts, some photosynthesis begins, but very slowly (like changing shift). But at the same time the plants are also consuming oxygen and producing CO2 (since they are living things). So only when the rate of photosynthesis is higher than the respiration rate will an excess of oxygen be present in the water (seen as visible bubbling). So they need time to achieve this point. Shut down the light too fast and they are cut off and have to start from zero again. Natural tropical daylight is roughly 10-11 hours so plants are adapted to this regime. So I really doubt changing it helps them. Like said earlier, just switch on the light manually at night to enjoy the tank for a while. But you can of course time it such that maybe the light switch on at 10 am and off at 8-9 pm.

Simon, i think becos your tank got some sunlight that's why ok.

[uncle_catz]

Thks Guys

An invaluable lesson indeed.

Cheers

[binbeto]

You can have a break in lighting in between the lighting duration.. It can be seen as a simulation that the cloud shade the plants from the noon sun.

This break in lighting is to combat algae as they dun light this "loss of light". But try not to have a light break of more than 4 hrs. Anything less than 4 hours, the plants won't be affect much but the algae will die off... At least this is the theory.

P.s. Each light duration should be at least 4 hours as this is the time needed for them to warm up.

[budak]

i still think the idea's not a sound one. a 1-2 hours siesta may be ok, but 4 hours is too long a break. And i hardly think many plants in nature enjoy a cloudy period at high noon, which is probably their best time for making whoopee.

[lip]

hi guys. I have kind of slowly (ok not that slowly) adapted my plants to receive lights from 4pm to 12midnite. any problems with that? my plants seems to be doing not too bad.

If plants learnt to adapt to a reversed schedule, should be fine right? i am kinda afraid of "shocking" my tank by switching on and off the lights as and when i feel like viewing the tank (esp at nite if i m to leave the lights on during normal daylight hrs).

[vinz]

Observe your plants. Some of them 'close' their leaves (e.g. gratiola sp.) when they go to sleep. If your plants start doing that before hours before your lights go off then daylight plus your lighting period is too long. Either shield the tank from daylight (no need completely, but the side that faces the windows) or reduce the lighting period.

[binbeto]

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On 7/29/2002 8:57:37 AM

i still think the idea's not a sound one. a 1-2 hours siesta may be ok, but 4 hours is too long a break. And i hardly think many plants in nature enjoy a cloudy period at high noon, which is probably their best time for making whoopee.
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Ya. I said. Less than 4 hrs... In tropical, cloud covering the noon sun is common.

[sherchoo]

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On 7/29/2002 10:09:18 AM

hi guys. I have kind of slowly (ok not that slowly) adapted my plants to receive lights from 4pm to 12midnite. any problems with that? my plants seems to be doing not too bad.

If plants learnt to adapt to a reversed schedule, should be fine right? i am kinda afraid of "shocking" my tank by switching on and off the lights as and when i feel like viewing the tank (esp at nite if i m to leave the lights on during normal daylight hrs).
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Don't really have to follow the actual day timing. My timing is quite similar to yours.

[lip]

Thx, vinz & sherchoo, for the information and confirmation.