# Direct Sunlight Causing Algae?



## Ben M (3 Mar 2011)

Hi, my brothers Juwel Lido 120 always has algae covering the glass. We don't have this problem in any other tanks, and I think it must be because it is facing a south-facing window (the only place it would fit). I have lowered the lighting to 6 hours per day, to no avail. I am dosing EI ferts, but no CO2, and it has the standard T5 lighting. Do you think this is the issue? There doesn't seem to be much algae on the plants. 

Are there any ways of combating this other than cleaning the glass regularly or adding a blind to the window?

cheers


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## Themuleous (3 Mar 2011)

Could well be the sunlight, which would be just like running a high light tank but without CO2 adn we all know what that does!  If its got regular lighting you could get rid pf the ferts as the plants wont need them, so will just be floating around the tank for the algae to use, which might be anther reason for the algae.

Sam


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## Anonymous (4 Mar 2011)

> Are there any ways of combating this other than cleaning the glass regularly or adding a blind to the window?



When direct sunlight hits your tank the CO2 is depleting very fast if the tank is well planted, you can avoid this either by increasing the CO2 or by using a PH controller (in some situations this is a better solution) or dose liquid carbon. Try and see if it helps, if not then you should cover the window.


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## Bobtastic (4 Mar 2011)

Isn't 6hrs of T5 a fairly high amount of light for a low tech tank anyway? That plus direct sun could push it over the edge?

Are you just using the internal Juwel filter too, cos the flow rate of those aren't the best. Is there a specific area that's affect more than others?


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## Ben M (4 Mar 2011)

thanks for the replies guys. I've spoken to my dad, and he is happy to put a blind up to stop the direct sunlight. All areas of the tank seem to be affected equally. We are using the internal juwel filter, and I don't think adding a different filter would be an option (as my brother isn't as in to fish as me). I'm not allowed pressurised CO2, and liquid carbon is too expensive, so I can't add any carbon. I didn't think that 6hrs of T5 was too much. I'm not using full EI ferts, I should have mentioned that I have reduced the dose because I'm not dosing carbon. 

cheers


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## nry (4 Mar 2011)

I had constant algae build up on my glass until I put a Koralia in - two weeks in and it almost stopped, glass only needs scraped every 3-4 weeks now and even that is just to remove a few sparse patches.  I also get some degree of sunlight although not often direct, normally diffused through a blind.


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## Garuf (5 Mar 2011)

Over winter I didn't get any sun at all now my large bay windows to my room let in so much light my plants are pearling by 10 o clock in the morning. I covered the tank to kill bga and it worked, got the tank back stable and kept the blinds shut, after a couple of weeks I got sick of living like a mole, opened the curtains, and low and behold within two days BGA and the plant health massively declining.


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## niru (22 Mar 2011)

Hi Garuf

I am slightly puzzled by your last observation. I have a high tech tank with EI, T5HO, and pressuried CO2. My tank sits in a covered wintergarden, so theres ample sunlight (mostly reflected) in morning and evenings. I have never had (till date!  ) any issues with BGA due to this. Only once when I was lazy to clean filters & not have good flow did BGA appear in minute amounts. I upped the Nitrate and added a Tunze flow and then do periodic filter cleans, and no BGA at all, plants pearling after 3 light hours ..

In general I am also confused about sunlight. Ignore or avoid this light source in a high tech tank with ample CO2? Info on various forums varies and I never found a clean answer to this. What do you all guys do about this? I am puzzled particularly when I read solar spectral distribution and algal response etc ...


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## Garuf (22 Mar 2011)

My light strike was/is direct, I put the reason down to the sunlight causing huge nutrient demand that couldn't be addressed. In general I'd say sunlight is bad, it's definitely plagued my last few tanks.


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## ceg4048 (23 Mar 2011)

There are no special spectral issues with sunlight that causes algae. It's simply that sunlight is bright and bright light triggers algae.

As a comparison, at equatorial latitudes, the PAR energy at the surface of open water or on open Savannah is on the order of 2000 micromoles. This is quite high when our targets energy levels are somewhere between 20-200 micromoles.

So if you don't have adequate CO2, nutrients and flow when the tank is being pummelled by high energy then you'll have issues. But how is that different from any other kind of light?

Cheers,


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## niru (23 Mar 2011)

Hi ceg

your explaination makes sense! One some web forums I recall reading that solar spectrum is much wider than most tube lights. Aquarium tubes have spectral energy distribution that peaks in frequencies which are most beneficial for plant growth. So given everything else is in order, plants make most of this light. For Sun, it has energy also in those wavelengths which plants dont necessariliy use, but then some opportunistic algae make use of this. And if the tank is on a thin edge, disaster is closer. This confused me, and is not in tune with what you mention and also what Diana Walstad mentions in her book as well. Also I thought that since most tanks are in living rooms where there is enough amibient light.. so those opportunistic algae should also make use of this! To extend further, perhaps they also use of IR or other heat "radiation" that plants might not be using  

In general then why is it advised to shield tanks from sunlight, if one has enough CO2 and nutrients in excess? Also, why does BGA show up on the front substrate? Is it also to do with some out-of-tank light issues?

Thanks as always!

-niru


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## ceg4048 (24 Mar 2011)

Hi niru,
           The paranoia regarding solar spectrum is a direct result of a couple of key misunderstandings which have themselves become myths:

Here is misunderstanding #1 which has turned into myth #1: 
"Aquarium tubes have spectral energy distribution that peaks in frequencies which are most beneficial for plant growth."
The fact is that all visible wavelengths (from 400nm to 700nm) are most beneficial to plants. These wavelengths are also most beneficial to algae. Plants and algae share pretty much exactly the same mechanisms for photon assimilation. The mechanisms are pigments. The most well known of these pigments are called Chlorophyll. There are a couple of different varieties of Chlorophyll, but generally these are mostly sensitive to blue and red wavelengths. However, there is still plenty of useful energy in wavelengths other than blue and red, so plants have other pigments that are sensitive to the yellow, green, and orange wavelengths. 

Not all environments are open Savannah illuminated with full solar spectrum. Many environments are shaded and filtered. Imagine a plant growing in the shade under a canopy of tall trees. The color of the light reaching the plant will be mostly yellow/green as it passes through the leaves of the tree. In an environment such as this the plants will have a higher percentage of pigments that are sensitive to yellow/green in order to maximize efficiency. They might also have a higher density of Chlorophyll in the leaf to squeeze as much energy from the available light as possible. In comparison, a plant growing in an unshaded open waterway will actually be in danger of energy overload so it will have a high density of pigments that actually reflect the blues, reds, and UV.

Plants therefore must have the ability to assess their environment from a spectral standpoint in order to determine what density and distribution of types of pigments to allocate to the leaves to prevent overload and at the same time to maximize energy usage. As a result, any spectrum that you provide to a plant will immediately be analyzed, and the plant will respond to that spectrum by developing and allocating the necessary pigments. 

So if you use only high intensity blue bulbs, the plant will determine that pigments sensitive to blue are needed but that a low density of these pigments are required and perhaps even that some pigments which reflect the blue to avoid overload. There are even pigments which can actually convert the blue to another color. if you decide to use red bulbs then the plant will perform an analysis and allocate pigments that maximize the use of red while avoiding overload. Any type of bulb that you use will be analyzed and responded to.

Here is misunderstanding #2 which has turned into myth #2
"...opportunistic algae should also make use of this! To extend further, perhaps they also use of IR or other heat "radiation" that plants might not be using..."

Plants are descended from algae. It was bacteria and then algae who figured out how to use solar radiation. They passed this knowledge on to higher plants. Therefore, whatever light is good for plants is also good for algae and whatever wavelengths are useful to algae are also useful to plants.

There is a biological equation however that results in a higher demand for nutrients/CO2 with increasing intensity. The difference is that plants require thousands of times more nutrient/CO2 than algae do. Therefore, under high spectral loading the plant will exhaust it's ability to uptake sufficient levels of nutrients/CO2. because of their much greater complexity and much greater mass, they need more nutrition and are less efficient at getting that nutrition, even if it's available. Plants therefore suffer easily under high lighting, but algae thrive under high lighting. Conversely, plants can survive under low lighting whereas algae suffer dreadfully under low lighting. That's why blackouts work against algae. Algae need more light because they have low energy reserves.

It's ironic that the first thing people think about when deciding to get into planted tanks is the idea of getting super sexy high lighting, and it's actually the last thing that the plants need, but it's just what the doctor ordered for algae.

The reason you tend to get BGA on the front of the tank is simply that there is the most ambient light at the front, combined with poor flow to the substrate. Try putting some black tape across the front for a few weeks and see how quickly it disappears. The BGA is telling you that you need to pay more attention to flow distribution to the substrate as well as that you possibly might need a bit more NO3 dosing.

Cheers,


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## niru (24 Mar 2011)

Hi ceg

as always, clean explainations, huh!?   



			
				ceg4048 said:
			
		

> The reason you tend to get BGA on the front of the tank is simply that there is the most ambient light at the front, combined with poor flow to the substrate. Try putting some black tape across the front for a few weeks and see how quickly it disappears. The BGA is telling you that you need to pay more attention to flow distribution to the substrate as well as that you possibly might need a bit more NO3 dosing.



After my last posts regarding algae and surface scums etc, I have a good flow in the tank. All leaves of all plants incl moss are swinging happily. I also upped my KNO3 in EI to almost 2X the dose, CO2 is maxed out (DC is yellow). Filters are cleaned frequently, added extra spraybar... Theres a small BGA on front glass-substrate area. I will stick a black tape for sure, but why should BGA gain foothold there? I mean what basics are getting wrong for BGA? And why ambient light is helping it? Is it because the substrate is NOT getting NO3 as good as water (ruled out as I have gravel and I frequently disturb it there), or some lack of O2 disturbs aerobic/anaerobic conditions that facilitate BGA over other bacteria there?? (as a check I syringed some H2O2 to some parts of gravel and can see O2 bubbles trapped there. so that part of substrate is O2 supplied.) I have read at very many places  abt BGA on front substrate, but no explaination why? So..... why?


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## ceg4048 (24 Mar 2011)

Well you do tend to get trapped detritus which decays in that areas well as light coming in from the front. Ambient light and reflections adds to the the total PAR at that location. Some tanks get GSA at that front area just below the substrate level.

Cheers,


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