# Different PAR values throughout the tank in Low Tech setups



## jcmv4792 (Jul 15, 2015)

Let's say the PAR at the lowest point is 25-30, some slopes(to create depth) achieve around 35-45 PAR, and you have some tall branches or rocks near the light(that I would assume gets near 100 PAR)

I've seen some setups where people attach moss, anubias, and ferns onto the branches as to not leave it bare, but I wonder how they avoid algae problems/stunting/melting when these "slow growing, low light plants" achieve more light than the plants at the bottom. Wouldn't the co2 levels be too low for the amount of light that the plants at the top receive? And even with tall, stem plants that are planted into the substrate, how do the top portions that receive much more light cope with the increased par levels?

And if you did leave the branches or rocks near the top bare, would algae still grow on those surfaces because of all the light?

How does this all work in a non-co2 enriched setup, with different PAR levels throughout the tank?


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## Raymond S. (Dec 29, 2012)

Water circulation will help out a lot here. Anubias don't do well when raised near the surface. They grow very slow normally often as slow as one new leaf every couple of months. Therefore the GSA covers their leaves when you have them in much light as
putting them on a higher limb would be.
I have a(two actually) 10g tank/w java moss on the walls. Most of it grows better in
the higher light it gets from being higher up in the tank. But a particular patch of it 
that is in a corner with less light and I think less current seems to be covered/w GSA
as it's much darker that the other moss in the tank and no green on most of the tips
as it usually has when growing. The reason it's on the walls...first set up.
http://www.plantedtank.net/forums/picture.php?albumid=14289&pictureid=43385
End and top view of filter(built in bio only)for size/shape reason.
Water intake bottom left. Air activated.
http://www.plantedtank.net/forums/picture.php?albumid=14289&pictureid=43401
Water outlet where bubbles are. Tank is older in this picture.
http://www.plantedtank.net/forums/picture.php?albumid=14289&pictureid=43393
Serious hair algae/serious overkill on the light... 100 PAR.
Tank last week. See top left for darker java moss in corner.
http://www.plantedtank.net/forums/picture.php?albumid=14289&pictureid=86169
I purposely run higher light to grow algae. Rivers/lakes etc have no one that cleans
the algae off of them so how can anyone say that no algae looks natural ?
But it has taken me a couple of years to balance the light so the algae won't "take over"
the tank and/or kill the plants.
I think you are inventing issues before they happen as every tank has higher light
the closer to the top you get. That hair algae in the third picture is from 100PAR(at the sub) and very little circulation when I had an Odyssea two bulb T5HO fixture.
I now run that same fixture, but with only one bulb and for only 7.5 hrs/w a split
photo period. So about 45-50 PAR at the sub now directly under the light.
Most plants will be OK/w your light. You just need to be mindfull of those very low light
type of plants not being up higher. This is java moss in lower light.
http://fishietank.com/wp-content/pl...shietank.com/wp-content/uploads/Java-Moss.jpg
http://www.fmueller.com/aquaristic/5G/java-moss.jpg
And this is java moss in good light.
http://cdn2.bigcommerce.com/server1...714/java_moss__52371.1329436872.1280.1280.jpg


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## Xiaozhuang (Feb 15, 2012)

jcmv4792 said:


> Let's say the PAR at the lowest point is 25-30, some slopes(to create depth) achieve around 35-45 PAR, and you have some tall branches or rocks near the light(that I would assume gets near 100 PAR)
> 
> I've seen some setups where people attach moss, anubias, and ferns onto the branches as to not leave it bare, but I wonder how they avoid algae problems/stunting/melting when these "slow growing, low light plants" achieve more light than the plants at the bottom. Wouldn't the co2 levels be too low for the amount of light that the plants at the top receive? And even with tall, stem plants that are planted into the substrate, how do the top portions that receive much more light cope with the increased par levels?
> 
> ...


Because that's not the way plants work. Full sunlight is 2000 PAR for example. Many aquatic plants grow in partially shaded forest streams that are much lower in PAR, but most are adaptable. The idea that low light plants need low light is just wrong. Plants stunt/melt when you switch parameters quickly (including light), but there isn't any plant out there that cannot be grown in high light


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## jcmv4792 (Jul 15, 2015)

Xiaozhuang said:


> Because that's not the way plants work. Full sunlight is 2000 PAR for example. Many aquatic plants grow in partially shaded forest streams that are much lower in PAR, but most are adaptable. The idea that low light plants need low light is just wrong. Plants stunt/melt when you switch parameters quickly (including light), but there isn't any plant out there that cannot be grown in high light


But in the hypothetical setup in the OP, wouldn't the plants near the top receive too much light for the amount of co2 available?(excluding stem plants that are rooted at substrate level.. I'm speaking strictly of plants either attached to hardscape near the top, or on elevated substrate slopes). Or does surface agitation from a HOB filter give a good amount of atmospheric co2 to plants right under the surface?


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## jcmv4792 (Jul 15, 2015)

I guess these examples are kind of what I am talking about. I'm not sure about the exact lighting for these setups but I would assume the anubias receive more than "low light" light levels all the way uptop.


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## Xiaozhuang (Feb 15, 2012)

There really isn't such thing as too much light for the CO2 available. That is a tank balance concept - not applied on a plant's need basis. (plants aren't gona die or become nutrient deficient because the weather has been sunny for awhile) The only downside of too much light is algae.

If you have lots of light, and lots of CO2, but lack nutrients, you get deficiencies. If you have lots of light, but no CO2 injection, the plant's growth rate is capped by CO2 lacking anyway - so a low level of dosing still works. However for many people, the second scenario leads to algae in the tank. Nutrients need to match CO2/light. But the later doesn't have to match nutrients levels. You can still grow anubias and whatever low light plants at very high PAR with no ill effects. (after acclimatization). The leaves may turn slightly lighter colored due to the high light. 

It's just wrong to say that anubias only grow a leaf every few months. Put it in a high light high tech tank with CO2 injection and you get new leaves every week or 2. - The problem is that most people have algae issues running such a setup, not that the plants don't grow well in it.


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## Hoppy (Dec 24, 2005)

When we say "low light" is 30 PAR at the substrate, that doesn't mean that all parts of the tank at a higher light intensity are not "low light". An aquarium that isn't lit by the sun will always have higher light intensity at the water surface, which is much closer to the source of light. Or, to put it another way, if your tank has 30 PAR at the water surface, it isn't likely that even "low light" plants will grow if they are planted at the water surface.

It would be extremely awkward and of little value to define "low light" as "about 30 PAR at the substrate, in the middle of the tank, with about 25 PAR at the substrate near the ends of the tank, about 45 PAR 4 inches above the substrate near the middle of the tank, about 35 PAR 4 inches above the substrate near the ends of the tank, from 50 PAR to 60 PAR 12 inches above the substrate near the middle of the tank, from 40 PAR to 50 PAR near the ends of the tank at about 12 inches above the substrate, etc." So, we instead, just use the intensity in the middle of the tank, at the substrate, to define "low light", knowing that for tanks of a non-standard geometry we might need to fudge that number a bit.

If we were scientists, we wouldn't use the simple definition of "low light". We would, instead, be discussing the minimum light intensity at the leaf needed to sustain growth of a given species of plant, and the range of light intensities over all of the plant leaves that will give optimum growth for that species, given the nutrient levels in the water, including bioavailable carbon, and the duration of the photoperiod.


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