# what makes a plant high light



## Capsaicin_MFK (Nov 15, 2009)

The fact that it requires high amounts of light to be healthy. A lot of the plants we use in this hobby are found in direct sunlight, which is a lot of wattage per gallon.

"high light" stem plants can be grown in lower light but they don't look as nice.


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## Sharkfood (May 2, 2010)

Just figure that most plants are low to medium light. There are only a few that really need high light, and they are usually stem plants or carpet plants. My primary tank would probably be considered medium light intensity, and I've yet to find anything that won't grow for lack of light.

"Medium light" will allow you to grow probably 99% (that's an arbitrary number, not the result of comparing all known plants) of all aquarium plants to their fullest. There are exceptions of course.


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## outcast (Jul 4, 2007)

many "high light" plants can make due with medium-low light as long as there is sufficient co2 enrichment (or alternative carbon source). When sufficient co2 enrichment is met, plants can allocate more resources (ie nitrogen) to producing chlorophyll enzymes to recieve a greater concentration of light rather than the rubsico enzymes to recieve carbon.

In many species there including quite a few said to be high light stems, they will look just as nice in a well balanced lower lit aquarium. Greater care needs to be taken in tank placement to reduce shading though. I've kept several carpeting plants with success in tanks that most would put in the medium to low light thresh hold.


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## plantbrain (Dec 15, 2003)

Can any of you name a so called, ......high light plant?

And what and how might you quantify the light in order to have a standard comparison?

I know of no carpeting plant that requires high light, say about 40 micromols to look nice. HC? Gloss, Hairgrass, clover, Erios, Sag's, chain swords, Liop's, Riccia, downoi, you name it........


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## sewingalot (Oct 12, 2008)

Tom, for people like me who don't have access to par meters, could you give us an example of the size tank, distance of the light from the substrate and amount/type of light you've used? I'm just having a difficult time with understanding when you talk in micromols.


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## psalm18.2 (Oct 16, 2010)

IMU high light plants are those usually partially submerged in nature with top sticking out of water. Plants like those found in ponds or shallow water near shallow creeks.


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## plantbrain (Dec 15, 2003)

sewingalot said:


> Tom, for people like me who don't have access to par meters, could you give us an example of the size tank, distance of the light from the substrate and amount/type of light you've used? I'm just having a difficult time with understanding when you talk in micromols.


20-40umol, low
40-60umol med
60 or higher, high light.

these are just what folks have shown, they might be a bit higher/lower per a particular species, but they all do very well at 40-50 umol.

I use typically 1.5w/gal of T5 lighting, about 1 meter away from the sediment.
When I switch to LED's some day..........it's be cut in half I estimate, so 0.7-0.8 w/gal. Not much energy vs the good old days of Yore when t12's at 3-4w/gal produced the same light mmol.

All my home tank pics you see?
They are all under or at 1.5w/gal.

A few older pics are higher, had MH's etc, but most are not high light tanks, and I've grown some 300-400 species, heck, I done lost count......but nothing has fit the claim of being a requirement for high light. Soe can live on less, but the range is only maybe 20 umol+/- between some 300-400 species.

So they are all low light as far as I can tell, in otherword, they all can grow well at low light. Why waste light and use excessive light an cause CO2 headaches? Indirectly, high light kills more fish than any nutrient dosing ever has or will. Since too much light causes many to jam too much CO2 gas, which is what kills their fish.

PAR meters are good for comparing very different lamp types, reflectors, distances, spot readings, depths etc. Watt/gal rules are terrible for this reasons. Even if you have a standard curve for a light etc, they change the brand or make a new model every 2-3 years anyway. So then that data needs redone and updated.

"umols" are more useful over time and over a broad range of aquarist lighting.
They are far from perfect, but given the trade offs, they are well suited for our needs.

Here's a so called high light plant with 44 umols at the sediment in a 24' deep tank using 2w/gal of PC lighting(or about 1.4-1.5w/ T5/gal equivalent).










I could jazz it up with photoshop, but why? 
As the above plants grow, they get closer to the light.
the umol goes up a far amount as well. So does the rate of growth, this _speed of growth_ influences color as well.

Here's HC in the same tank:










Oh heck, it's not just me either, here's 40-50micromols from AFA in SF's 180 cm ADA tank:



















Ranked 20ths in the AGA contest.
So if you can do better:thumbsup:

It has a different W/gal ratio roughly 450w/160gal = 2.8w/gal.

You also have a diffetrent slope in the AFA tank, the sediment is 25-30cm high in the rar, so the reading is skewed even less if you reduced the sediment to say 8cm uniformly. The tank of mine has about 4cm rise front the rare, not 14cm or so like the AFA tank.

So the distance is greater and we'd expect les slight at this depth vs the AFA tank.

But they are the same.

So it's more like a 2:1 difference if you used the W/gal ratios, but usign a PAR meter, we see they are exactly the same. Such information is very useful, not just to describe the amount of light required for nice scapes, but the species as well.

The irony is that many poo poo me about suggesting folks not test PO4/NO3 etc.......but they argue that folks do not need to test light. Where does growth start?

Sort of common sense.


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## sewingalot (Oct 12, 2008)

Now that gives me a lot better understanding. I know it won't be exact, but it's nice to be able to put things in layman's terms just to get a baseline. Especially for cheap people like me that won't be getting a par meter anytime soon and is in the middle of no where to borrow one.

Do you use high-output or normal-output T5's? I've often wondered how much difference there is between the two. If I ever get super rich, I'm totally buying a dozen of these Par meters to pass around to TPT members.

Thanks for spelling it out for me to be able to understand.


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