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Discussion Starter · #1 ·
People at the PT might have noticed this, but something interesting has arisen about plant-light requirements. Shalu, setup a 10g with inert gravel(no additives) and the tank is lit with 2x15w(2700K) CF bulbs, yet she is succesfully growing healthy stems of Tonina fluviatilis, R. macaranda, Cabomba furcata, E. azurea, and R. wallichii. She doses traces and macros every week(after a 25% WC), but doesn't use any C02(unless you count Excel). Can someone explain this strange phenomena? Could this have to do more with light intensity? I mean everyone has been recommending more light for smaller tanks, yet this seems to prove previous theories as false.

Link- http://www.plantedtank.net/forums/showthread.php?t=14469&page=1&pp=15
 

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Raul-7 said:
Could this have to do more with light intensity? I mean everyone has been recommending more light for smaller tanks, yet this seems to prove previous theories as false.
I don't think it proves previous theories false at all. The problem here is most likely misunderstanding of the "more light for small tank" advice. If you have 3WPG over a 90G tank, then you would probably need 6WPG over a 5G tank to achieve the SAME light intensity produced by the 3WPG 90G. In other words, 3WPG over a 90G tank is considered high light, but 3WPG over a 5G is considered low-moderate light.

Shalu's 3WPG 10G tank is moderately lit by today's standard. Coupled with the fact that it is a screw-in type bulb with a 2700K rating, the utility of light produced is less than that of a standard CF bulb. Add on the lack of a reflector and her tank is moderately lit at best. This places her in the province of the typical non-CO2 tank. With a non-fertile substrate, she finds herself supplementing the water column. She also regularly doses Flourish Excel (CO2 substitute); thus increasing the number of plants that can survive in such a setup. This type of tank is long advocated by Mr. Thomas Barr: moderately lit tank with CO2 supplementation.

As such, shalu's tank doesn't surprise me in that respect. However, this tank does drive home the fact that Glossostigma elatinoides (among others) does not require high light to produce a low carpet.
 

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Also providing my two cents, from personal experience, aquariums withsmaller dimensions do need more watts per gallon than larger aquaria. I observed this when, having 4 wpg over a 10g with a PC+reflector, the Rotala rotundifolia and Rotala rotundifolia "Green," which usually grow at an angle or even creep under high light intensities, were actually growing vertically to the surface. Everything grew and thrived, but did not show the growth habits these same plants would show if they were placed in a 4 wpg 75g.

I observed the same in my 5g cube, where 2x18w of PC lighting was not sufficient to keep Hemianthus micranthemoides from becoming leggy and nonbushy.

The addition of more lighting and/or more efficient reflectors have now remedied both issues completely.

I could grow stem plants with a mere 1.75 wpg (1x96w) over my 55g. I had some very orange and robust R. wallichii in there. Plants grow more slowly, but certainly can grow and thrive in less lighting than most recommend as a necessity. It all depends on the effect/results you want.

Carlos
 

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I would like to say to give that tank more time and see how the plants are doing. Plants will store energy when "non-prolific" conditions arise. The tonina might be growing from its stored energy since it has been in the tank for ~1 week. Also the glosso looks like marsilea to me due to the varied leaf sizes. Am I wrong? Or is it glosso on the left side and marsilea on the right front?
 

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gnome said:
Hee-hee! I just had to interject... Shalu (Sha) is a "he." (cackle-cackle).
My sincerest of apologies Sha. #-o "Shalu" reminded me of an old TV show where the lead character is some blond Amazonian warrior. No not Xena. :razz: Forgive my ignorance.
 

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No problem, cS :) hard to guess it right from the handle some times, but its actually my real name.
I would agree my 3wpg PC over 100g is brighter than the 3 wpg cf in the 10g for sure. We probably went overboard a bit in the persuit of growing "highlight" plants.

Yes, it is some Marselia on the right side. It is doing very little, the glosso is taking over pretty soon. It will probably take 4 months to get the full carpet out of glosso under this condition, but that's the idea of a slow, low maintanance tank. I can only keep glosso looking good for 2 months max in my 100g CO2 enriched tank, don't know how to maintain it aferwards.

I unknowingly let NO3 drop to 0 and some plants had stunted growth. With NO3 addition, plants are growing surprisingly fast. A little too fast for a slow tank. I might stop Excel soon.

Toninas are new plants to me. These plants might have a relatively low tolerance of kh/gh, but maybe not as low as commonly believed. In 100g kh=8, gh=13, 10g kh=4 gh=8(played with RO and Ca addition). I put 1 stem of t. fluviatilis in my 100g and 10g respectively. the stem in 100g grew twice as fast as in 10g, but I noticed the lower leaves are turning brown. The stem in the 10g is greener, does not look stressed. I suspect the lower hardness does play a role here. I can lower the hardness in 10g further if necessary, it is easier to experiment with a smaller tank. I also got some tonina sp. 'belem' a week ago. Looks like the stems in 100g is experiencing some melt down, while the one in 10g is still green, it might even be trying to grow a bit. Again, hardness might be an issue.

But I don't want to conclude too early yet. I have struggled with several plants in the 100g in the past, but eventually I have figured out(Ca addition even with high gh): rotala macrandra, r. magenta, r. wallichii, nesaea sp. I could have drawn some wrong conclusion: they don't do well in my warm discus tank at 83F, but that was not the real cause. I like the challenge of growing difficult plants more than aquascaping at this point. Its about patience, changing one parameter at a time and wait, wait, wait, at least for a few weeks.

I will move more and more difficult plants into my 10g experimental tank and will be posting update pics in the PT forum from time to time.

So is there a plant you can't grow? I might want to try it :)
 

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Discussion Starter · #8 ·
But people, remember his tank is lit with 2x15w CF, not PC bulbs. Meaning lots of light-restrike and incandescent reflectors aren't up to par with parabolic reflectors. I mean 3wpg CF is nowhere near 3wpg PC, but yet he's succesfully growing high-light plants. Do you get what I'm trying to say?
 

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Raul-7 said:
But people, remember his tank is lit with 2x15w CF, not PC bulbs. Meaning lots of light-restrike and incandescent reflectors aren't up to par with parabolic reflectors. I mean 3wpg CF is nowhere near 3wpg PC, but yet he's succesfully growing high-light plants. Do you get what I'm trying to say?
I will post a pic of my light fixture here soon. One of the bulbs' glass tube is almost separated from its base, I have to use a rubber band to prevent it from falling into the water. :) When placed over an open aquarium, the bulbs sure don't last 6 years as advertised.
 
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