# Longer photoperiod



## idris (5 Nov 2011)

Obviously I've failed to assimilate  some vital piece if information, but here goes...

Algae is, at least in part, due to plants not consuming all the nutrients in the water.
Plants only consume nutrients when they're photosynthesising.
Plants only photosynthesise when there is light.
So why not leave the lights on longer to consume more nutrients and reduce algae?


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## andrejacobs81 (5 Nov 2011)

Algae also photosynthesises.


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## Alastair (5 Nov 2011)

I think it's something to do with plants using so much nutrients and co2 in the early hours of the photo period and by the last part of it they are on cruise control so if lights are on too Long then algae takes advantage of the excess nutrients not being used.......I think! 
I'll probably be way off though ha


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## Aquadream (5 Nov 2011)

There is no such thing as excess nutrients, but insufficient amount of nutrients. If plants consume all nutrients that will very likely lead to nutrient deficiency and will result in algae bloom.

Plants photosynthesize when there is enough light and CO2. It is best that CO2 is a bit more than the plants would require in certain light conditions.

It is the same with nutrient levels. It is best to have more than required than to fall in shortage.

The bottom line is this. If plants do well algae does not.
Plants do well only when there is no shortage of anything that they need.

Longer photoperiod than 12 hours is not advisable. Also for longer photoperiod the light level should be lower.


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## ceg4048 (6 Nov 2011)

idris said:
			
		

> Algae is, at least in part, due to plants not consuming all the nutrients in the water.


Totally wrong. Algae really do not care about nutrient levels. Algal blooms occur in both oligotrophic as well as eutrophic tanks.


			
				idris said:
			
		

> Plants only consume nutrients when they're photosynthesising.


This is also not true.


			
				idris said:
			
		

> Plants only photosynthesise when there is light.


Check.


			
				idris said:
			
		

> So why not leave the lights on longer to consume more nutrients and reduce algae?


This is the logic promulgated in The Matrix. People are programmed to believe that adding more light and reducing the level of nutrients solves their problems and these are exactly the wrong things to due because the logic is clearly flawed.


			
				Alastair said:
			
		

> I think it's something to do with plants using so much nutrients and co2 in the early hours of the photo period and by the last part of it they are on cruise control so if lights are on too Long then algae takes advantage of the excess nutrients not being used.......I think!
> I'll probably be way off though ha


Yes this is so far off you'll need a Klingon Bird of Prey travelling at maximum warp just to find it.

As mentioned by Aquadream, in our tanks algae play the role of predators who feed on the remains of weakened higher plants. There is no relationship between nutrient levels and the blooms. The blooms arise as a direct result of unhealthy plants. Just because a plant appears to be growing that does not automatcally mean that it is healthy. Furthermore, in order to stay healthy, plants require thousands of times more nutrients than algae do, simply because of their much greater mass, as well as because of their much greater complexity. That's why it is always a failed policy to restrict nutrients, because you will always wind up starving plants into oblivion long before you will starve any algae. Plants can also survive on much lower light than algae can, because they have much higher reserves of energy and they can make adjustments to low light by increasing their chlorophyll density to make more food with less light.

Cheers,


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## idris (6 Nov 2011)

Thanks Ceg.
Umfortunlately I had to look up definitions for 4 words, an only one of those was Kilngon. 

But on a more serious note ....
So my algae means I have unhealthy plants. But how do I tell what's wrong with them?


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## foxfish (6 Nov 2011)

Easy, they need some gas


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## ceg4048 (6 Nov 2011)

Easy, just check JamesC's Algae Guide.
We've already discovered the correllations between the deficiencies and the symptoms, so all you have to do is identify the algae species and that will tell you what's wrong with the plants. If, for example you see BGA then you know automatically that the plants are suffering a nitrate deficiency syndrome.

What you do to fix the problem is either to add more of what's defficient, or improve your flow/distribution, or to lower the light intensity....or a combination of all these. The principles are really quite easy. In practice it's a little bit more difficult. But, knowing the path is more important than anything else.

Cheers,


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## idris (6 Nov 2011)

Ceg - I'd read the algae pages but completely failed to make that leap of logic. Ta. 
Fixfish - you know damn well that's not going to happen.


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