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Why so bright, is it good to see the light in the tank?

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Blev medlem: 28 jan 2010, 00:40

Link to Tropica's web site of articles

Inlägg av Plantbrain » 28 jan 2010, 20:10

This article is excellent in that explains the dynamics between light intensity and CO2 enrichment.

Few hobbyist measure light or CO2 effectively. This leads to many misconceptions and myths. Why do aquatic plants grow well without CO2 in some aquarist aquariums? While others have troubles?
How is that many use CO2 gas have excellent growth, while others do not?

Light explains a fair amount of this.

While wildly popular on the internet, limiting nutrient has long been "all the rage" for many hobbyists. However, not looking at the whole plant's demand is short sighted. It is the sum of light, CO2 and nutrients that drive plant growth.

Aquarist have few tools to measure light and CO2 effectively and calibrate them against know standards to ensure accuracy.
This led to nutrient driven management methods rather than a holistic approach, which is understandable given the tools available.

PAR light meters are widely being used, particularly for Reef aquariums and the cost has come down to the point where hobbyist can buy and share a light meter so that we can compare the light intensities among different locations and different aquariums.

Light intensity/duration is the most stable parameter aquarist have for aquatic management of growth. Nutrients change much more rapidly and require more testing and more difficulty in the measurement, PAR light meters are easy to use, quick and painless.

While Tropica and their researchers have long concluded that good CO2 enrichment and lower light provides the best management for most aquarist' goals, few seem to listen to them, myself and others.

Algae are not limited by CO2 or nutrient in any aquarium.
Loight is about the only parameter of the 3 that they are "limited".
Light energy also cost more than water changes, and represents the highest waste/excess from an aquarium.

So if a sustainable approach efficiency is a goal, good low light, good CO2 enrichment, a good mix of water column + sediment based dosing is suggested.

ADA's lighting is similar, using open tops and while the wattage might seem high, the actual PAR in such tanks is much less, roughly in the 30-50 micromol range. The distance from the light source plays a large role since they use suspension lights which can be adjusted upwards and
greatly reduces intensity. So indirectly, ADA also suggest low light and CO2 enrichment as well.

We might conclude that most horticulturalist and hobbyist that have been in the business/hobby for decades all use a similar method.

Is more light better?
Not likely for most hobbyist.

A "light limited planted aquarium" might be a much better concept.

This tanks falls into the management group:


The light is about 40micrmols at the bottom, I use about 1.7 w/gal or .4 w/liter, the red plants and the foreground plants do excellent even at 65cm depth and with the lights raised another 30 cm off the top of the water.

Sediment is enriched clay, ADA aqua soil, water column is a mix of KNO3, KH2PO4, GH mix, Trace mix dosed to non limiting levels and good CO2 misting.

Since nutrients are non limiting in both locations, CO2 is good, low light is maximized and I get the most efficiency out the low light added.
This also makes the demand for nutrients and CO2 lower than I would have at high light, thus the management for CO2 and nutrients is much easier, and I can dose less.

So using less light makes all downstream management much easier and more stable.

I still have excellent health and growth, but it's far more manageable.

Try this, reduce you light slowly and progressively and see how it affects the aquarium,

Next: adjust the CO2 carefully/slowly and also add more current so that the O2 levels are also higher. This will make adding more CO2 less stressful for fish (they breath in O2 and exhale CO2 so it is the total of both CO2/O2 that matter, not just CO2 alone) and better mix the CO2 in the plant beds.

Tom Barr

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Inlägg av PatrikMalmo » 28 jan 2010, 20:13

BIG welcome!! :)

Thanks for your post!!
End Of The World Party
(just in case)


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Inlägg av peterhaack » 28 jan 2010, 20:26

Thanks Mr Barr and Welcome!

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Re: Link to Tropica's web site of articles

Inlägg av Lingonfil » 29 jan 2010, 00:17

Good and detailed article (linked).

Intersestng post as well.
Plantbrain skrev: I still have excellent health and growth, but it's far more manageable.
So the reason for turning down the lights is to get a more stable tank (and perhaps reduced electric bill)?

If one don't want to buy a new lights source what would be the best way to reduce lighting? Shading with floaters, screening of light with a net, raising the light source from the water line. Those changes wouldn't effect ones electric bill, and one would be "wasting" light.

If you had an overdimensioned lightingequipment would you rather "waste" light and get less light in the tank and hopefully a more stable tank. Or would you maximize the efficeincy of your light output and adjust Co2 and nutrients?

Gustav Ek
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Inlägg av Gustav Ek » 29 jan 2010, 00:18

Very interesting article, something that I surely will try out when adding c02 to my tank. Thanks and welcome!

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Inlägg av Roolo » 29 jan 2010, 20:44

Welcome to plantswap mr Barr, its a honor to have have you here!
I do have some questions, in which, it would be intresting to hear your opinion.

#1 In your first post in this thread, you were talking about having 40µE/s at the bottom of your tank. Do you consider 40µE/s to be "High Light" or "Low light"? How do you relate 40µE/s to µE/s/m2 (area of the sensor radiated is needed?)

#2 Most art descriptions of aquatic plants, are talking about "light needs",what do you consider as Low - High light needs, expressed in [µE/s/m2]

#3 In a recent thread:, we had a discussion about light ranges Ivo Buskos article: were used as a reference material in the discussion. I tried to interpretate Ivo:s excellent article in order to have a formula, that should be easy to use.

The formula outcome was as follows:

L = Light amount [(µE/s)/m2]
P = Light source electrical power [W]
A = Bottom Area of the Tank [m2]
PAReff = PAR-Efficiency [(µE/s)/W]
Reff = Reflektoreffektivitet [%] (25% for no reflector and approx 80% for a "good" reflector??)

L= (P*PAReff*Reff)/A [(µE/s)/m2]

What is your opinion bout this formula?

PAReff is retrieved from Defdacs Calculator :

BR Roolo

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