light question

rick4him

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Mar 4, 2008
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I have a 25 gallon planted tank, with pressured co2.

My question is how long is best to leave lights on?

Also i have one 65w - 10,000k and one 65w - 6700 k bulb.

I really like the look of the tank with just the 6700k bulb one. I like the blue tint I get.

Question If I turn one just this one bulb for a few hours a day, and turn the other one off, does my photo pierod go down by 1/2 on my plants? (i'm assuming this because I'm turning 1/2 my lights off.)

Thoughts? Suggestions?
 

creighton

Guru Class Expert
Jun 18, 2007
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So you have 2 X 65watt bulbs...why don't you try turning one on in the morning for 2/5 of your photo period have a mid day burst with both on for 1/5 of the photo period, then have on bulb on to finish the rest 2/5 of your photo period. 130 watts is kinda intense for only a 25 gallon, but you can try it for a few hours a day and see what happens. You'll probably have better success with just one bulb on, and I think 65 watts is plenty if you have good reflectors. I use a 10 hour photo period on all my tanks, but others do different things.

More light=More demand for nutrients=more demand for CO2. With such a fast rate of growth things can run out quick. I have heard Tom state this many times ( please correct me if I'm wrong Tom)

If you turn off one bulb you are just reducing the light levels not the photo period.

Hope this helps a bit.
 

rick4him

Prolific Poster
Mar 4, 2008
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Hmm - I don' t think I agree with you. Lots of people have 5wpg. I am putting good co2, and good ferts in the tank, so the light doesn't do any harm. You don't have to worry about things running out quickly if you are dosing enough. I asked Tom if he thought my dosing and set up was ok, and he said in fact he did the same thing on 3 tanks, and sent me pictures, so I don't think it's wise to keep only 1/2 of my lights going on for most of the day.

creighton;23516 said:
So you have 2 X 65watt bulbs...why don't you try turning one on in the morning for 2/5 of your photo period have a mid day burst with both on for 1/5 of the photo period, then have on bulb on to finish the rest 2/5 of your photo period. 130 watts is kinda intense for only a 25 gallon, but you can try it for a few hours a day and see what happens. You'll probably have better success with just one bulb on, and I think 65 watts is plenty if you have good reflectors. I use a 10 hour photo period on all my tanks, but others do different things.

More light=More demand for nutrients=more demand for CO2. With such a fast rate of growth things can run out quick. I have heard Tom state this many times ( please correct me if I'm wrong Tom)

If you turn off one bulb you are just reducing the light levels not the photo period.

Hope this helps a bit.
 

creighton

Guru Class Expert
Jun 18, 2007
192
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16
Well, I stand corrected :eek: .

In my experience I have had great growth for a while on tanks with around 5wpg, but as soon as something went wrong it snowballed and things got out of hand very fast. It sounds like you know what your doing though :) !
 

Tom Barr

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Jan 23, 2005
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rick4him;23519 said:
Hmm - I don' t think I agree with you. Lots of people have 5wpg. I am putting good co2, and good ferts in the tank, so the light doesn't do any harm. You don't have to worry about things running out quickly if you are dosing enough. I asked Tom if he thought my dosing and set up was ok, and he said in fact he did the same thing on 3 tanks, and sent me pictures, so I don't think it's wise to keep only 1/2 of my lights going on for most of the day.

Well, you can try this 1/2 day approach and be fine, likely better, if you have CO2 issues.

I have little trouble with high light.
But.......less light is easier.

And it does place less demand on everything else.

We all can make many mistakes etc, and this can help mitigate the issue(if there is one). If there is not issue with CO2/nutrients, then it does no harm either.........

Regards,
Tom Barr
 

VaughnH

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Jan 24, 2005
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Light is what determines the maximum rate of growth of plants and algae. So, if you are able to maintain the tank well, prune often, keep it fertilized well, provide adequate CO2 at all times while the lights are on, 5 watts per gallon is fine. Many of us are too lazy, too involved with other activities, or just not preferring such rapid growth, so we prefer a lower light level. I'm one of the lazy ones.