Understanding Photoperiod...heh heh...period.

So, I have a question...

Let's assume that plants can only photosynthesize light for 8 hours. So, we set our lights to go on timers so that they are on at specific times of the day.
Now, let's also assume that, because people work during the day, it makes more sense to have the timers go on closer to the evening, instead of in the morning when no on is at home.

If the tank were close enough to a window where it's getting SOME sunlight, do the plants start photosynthesizing with the little amount of light that's coming from the sun? If so... does that cut into the total photoperiod?

Did any of that make any sense? I'm not good at explaining things. Let's see if I can do it this way:

I have my timer set to turn on at 3pm and then turn off at 11pm, totalling in 8 hours of light.

6am - Sun starts to rise - lights are still off.
8am - Sun is blasting its light and ambient light comes in from the windows. Plants start to "bend" toward the light source (wherever the window is)
-
-
3pm - Lights turn on.
-
-
11pm - Lights turn off.

So, basically, from 8am onwards too 11pm, the plants are getting some source of light, totalling to about 15 hours of potential light.
Does that mean from 8am - 4pm the plants stop absorbing light, and from 4pm-11pm I'm just providing light for algae growth?

My 55 gallon tank is about 12 feet away from any window, but I've noticed that in the mornings when the lights on the tank are still off, the plants tend to "bend forward" towards any light they can grasp, which is a window that faces somewhat directly infront of the tank, as if the plant is trying to get whatever light it can get from any ambient light in the room.

So, I guess in short...
Does ambient light, interfere with photoperiod? Does that mean I should decrease the time I have my lights on? That wouldn't be very fair for plants that require higher light though...so how does one get around this?

Confused yet? Because my brain is fried trying to explain this. LOL
 

Seattle_Aquarist

Well-Known Member
Hi PokeSephiroth,

Actually, plants can photosynthesize for much more than 8 hours, plants do hot have a built-in 'clock'.

That said, sufficient light intensity, and duration, are required for the Calvin-Benson cycle and photosynthesis to actually start and perform efficiently. Although the plants may be 'reaching' for the natural light very little photosynthesis (if any) is likely occurring. No change in your photoperiod should be necessary.
 

flamechica

New Member
I totally get what you are trying to say. I don't have the answer in the photo period stuff. My 10g is sorta in front of a very large window and when I upgraded my hood from the crappy dual 15w regular light bulbs to the T5, I had a massive algae outbreak. I figured it was due to a better light source combined with being in front of the window, so I put foil on the back of my tank to stop the sunlight coming in. Eventually the algae went away. Not sure if it had anything to do with the foil or if it was just everything balancing out, but if you are concerned about it, that's what I would do.... Of course, foil isn't very pretty. I have a tank background on order now, since I ordered so much stuff for my hex tank, I threw a background in on one order for the 10g, so I can get rid of the nasty looking foil. Lol
 
flamechica: Ahhhh... well, I applied some window tint on the back of the tank, so that probably has helped block out some ambient light from the back... I love the tinted stuff, actually :) It's also "mirrored" on one side, so it makes the front of the tank look deeper than it really is! :D

I think Roy (Seattle_Aquarist) helped answer my question though!
 

flamechica

New Member
Ooooo! I bet that mirrored tint looks cool! I was typing on my phone, so totally didn't see his post. Glad he got it answered for ya!
 
flamechica: It's really awesome stuff! Kinda tricky to apply, especially getting out all the trapped bubbles, but once you get the hang of it, it becomes easier to put on. Here is a 12gallon rimless tank that I tried it on, before I went on to the 55 gallon tank. I like how it's semi-transparent. It also helps hide all the chords and wires so that you don't see it when you're looking from the front! It also has a similar "light diffusing" effect IF you have a backlight on the back of your tank.
 

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flamechica

New Member
That's cool! My hubby used to apply vinyl on windows and signs so I know the perfect person to do this for me ;-)
 
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