Daylight And Artificial Light

rjugas

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Jan 15, 2018
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Hi,
I didn't find similar topic so I will ask you guys: How do you handle the daylight?
I am lighting my tank 1pm-8pm, CO2 gassing 12pm-7pm. My windows is oriented directly towards west. Of course the sunlight is shining indirectly into the room since morning and is also shining into the tank. I can see how Limnophila is oriented towards the window.
I currently has some fibrous algae so I am asking myself, can it be a problem?
Also, does the plants start the photosynthesis since morning? I think yes and with low levels of CO2 for sure. So how are you dealing with this? Are you using the daylight and set the CO2 correspondingly or are you limiting it?
 

Kyalgae

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Aug 25, 2016
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Even though I have a tank way back from my windows, in the winter time the evening sun can shine directly into my tank. I pull the blinds usually to prevent that. If I don’t my plants start using up my co2 faster than I can inject it, so it ruins the nice stable co2 level. Stable co2 throughout the day means healthier plants and less algae.

Sunlight is going to vary in intensity, so it would be a real challenge to balance co2 to match the sun every day. I had a hard enough time with just my artificial lights.
 
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Allwissend

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Hello,

many exceptions to the rule are possible here no doubt. Before going more into the subject let me say that one can have planted aquariums with just (shaded) sunlight and no/low algae.Such aquariums are usually nutrient limited in the water column. But for the purpose of this forum, I think it is more relevant to focus on aquarium with water column fertilization.

I had several setups where sunlight only reached a corner of the aquarium. I only ever struggled with algae in those corners (BGA and BBA being the exception here). Thus my general suggestion would be, when possible limit daylight in aquarium rooms.

There is a discussion of phototropism levels and photosynthesis threshold levels. Positive phototropism refers to plants growing towards the light. Light here only has to be strong enough to reduce auxin levels in the parts of the plant exposed to light. This level is lower than the photosynthesis threshold. So plants may bend towards lower light levels before they can actually use.

Why is this distinction important ? Because plants need good CO2 levels when they start photosynthesis. But indoors, daylight levels may not be strong enough to induce photosynthesis and thus not directly affect the aquarium. Plants like R. wallichii and Myriophyllum sp. will open and close their leaves when they expect the light period to start and when they had enough light for the day. If you notice them opening when way before the artificial light comes on, it is likely that environmental light levels are too high.
 
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tiger15

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Aug 12, 2017
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I also have window filtered sunlight that moves from one end to the other end of my tank over a couple hours during winter months. But majority of my plants are fern, Anubias, Buce and Crypts that don’t open and close with photo period. So how is it possible to know there is excessive sunlight. Do non stem plants have photo active period similar to stem plants.
 

theobroma

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Mar 9, 2018
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New England
I know that indoor set-ups have their own restrictions, but I have kept a number of tanks outdoors in the summer months, getting plenty of sun. It's a fun way to experiment,and since I don't put much effort into hardscape, it's mostly about plants. You bet the parameters are crazy high sometimes, but you get to see what some plants, which we only see indoors, are capable of. But what I wanted to add here is about algae. I noticed when growing a lot of emergent plants in full sun that there is almost no algae, even when nutrients are quite high (fertilizer draining in from potted plants that I set on bricks to stay just at water level. The plants below - species that need high light levels - are growing so fast I believe they vacuum up anything that gets in the water. In other words, they out-compete the algae and the water stays clear. Of course, things can go bad fast when you push them this hard, so I wouldn't recommend it. Just an observation.
 

Allwissend

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Yes, those plants will also have their levels where photosynthesis brings energy to the cell. As they are mostly shadow plants, their threshold is even lower.

Some cryptocorynes also close their leaves up, although not as extreme as stems. You will also see new leaves growing to maximize exposure of the top leaf part to light.

You can measure light intensity, so a lux meter or a PAR meter would do. Although what is enough depends from. Sp to sp and plant to plant. Algae in the areas exposed to natural light is a sure bet it is too much.
 

tiger15

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Aug 12, 2017
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I know that indoor set-ups have their own restrictions, but I have kept a number of tanks outdoors in the summer months, getting plenty of sun. It's a fun way to experiment,and since I don't put much effort into hardscape, it's mostly about plants. You bet the parameters are crazy high sometimes, but you get to see what some plants, which we only see indoors, are capable of. But what I wanted to add here is about algae. I noticed when growing a lot of emergent plants in full sun that there is almost no algae, even when nutrients are quite high (fertilizer draining in from potted plants that I set on bricks to stay just at water level. The plants below - species that need high light levels - are growing so fast I believe they vacuum up anything that gets in the water. In other words, they out-compete the algae and the water stays clear. Of course, things can go bad fast when you push them this hard, so I wouldn't recommend it. Just an observation.

I grow submerged and emerged plants in outdoor tubs in summer. Yes, they don't get BBA, but green water and sometime slimy green algae
 

theobroma

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Mar 9, 2018
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I have had green water sometimes. I think it may be, for me, from being careless and not cleaning my tub or tank well when I'm setting up for the season. That gives any algae cells/spores that are present a head start before the plants get adjusted. If I run a diatom filter once the problem with green water doesn't usually reappear. If I'm really busy or lazy sometimes this doesn't get done, but the floating algae precipitates out and doesn't cause more trouble. But of course weather can have some effect,so I can't say I've got it all figured out.