Low/Medium/High light plants

[James0816]

can someone explain this to me? I have two plants currently in my tank...don't know what they are...will post a pic shortly. anyway...whats the difference...i presume its how much light is neccessary to grow.

I currently have a 29 gal with a 17watt bulb.

[TwoTankAmin]

Different plants require different ligh levels to thrive/survive. Your lighting lvel will support very few plants.

As a rule of thumb: low light = 1 wpg; moderate/medium light = 2 wpg; high light = 3 wpg.

[KnaveTO]

Actually I thought it was more

Low - 1watt/gallon
Moderate - 2watts/gallon
Medium - 3watts/gallon
High - 4watts/gallon

[TwoTankAmin]

One of my favorite plant quotes is from Karen Randall who wrote in her article "Lighting for the Planted Tank" :

Recently, in the typical American thinking of “more is better,” I’ve come across people using upwards of 5 watts per gallon on their planted tanks. While it is possible to manage such a system, it is more work. I have yet to meet a “high intensity” plant that could not be grown well in a tank of normal depth at around 3 watts per gallon. If the plant is not growing at 3 watts per gallon, look to other causes for the failure first.

For the complete areticle go here http://www.csd.net/~cgadd/aqua/ah_main/mar1998.html

[Slappy*McFish]

Crypts, Java fern, and Anubias will grow at low light levels. But 17w on a 29g is extremely low. Add another light and get some Flourish Excel.

[AnDr3w]

I have like exactly 1.6 wpg and I can barely grow a sword. lol.

[Slappy*McFish]

The kind of lights used plays a roll, as well. I would go with a 'GE Aqua Rays Freshwater/Saltwater 9325K', a 'Triton' or a 'Penn-plax Ultra TriLux.' Combining these lights gives excellent results, as well.

[plantbrain]

Different plants require different ligh levels to thrive/survive. Your lighting lvel will support very few plants.

As a rule of thumb: low light = 1 wpg; moderate/medium light = 2 wpg; high light = 3 wpg.

Sounds dead on to me as well:)
I definitely agree.

FYI, I've yet to meet a plant I cannot grow well at 2w/gal.

That's 300+ species and 15 years worth of growing experience using CO2.
In general, more light= more work.

Regards,
Tom Barr

[James0816]

how do you add another light? i don't see how this is with the hoods on the tanks? is there another type of hood or what? guess they just dont have bigger watt bulbs eh?

[Nolapete]

Actually I thought it was more

Low - 1watt/gallon
Moderate - 2watts/gallon
Medium - 3watts/gallon
High - 4watts/gallon

no, 3 wpg + is high light

[loaches r cool]

Most ditch the 'stock' hoods that come with the cheaper kits. About the only way to keep it is to gut out the hood, removing the light, ballast, endcaps, etc, and getting something like an AHSupply.com kit that uses Power Compact lights. Off hand not sure how long a bulb you can fit in your existing hood but probably either their 36W or 55W kit.

And arguing about the finer details of the wpg rule of thumb is equivelent to arguing about the stocking inch per gallon rule of thumb. They are terribly innacurate and dont account for many variables. Treat it as a loose guidline to get you in the ballpark only.

[plantbrain]

You know, I've heard this arguement many times about the watts/gallon rule being off, inaccurate, bad, we "need" some better alternative etc.

Okay, let's see what can be done about it and if this is really true.

I've really never seen it ever not work in the avergae tanks folks.
So while I've bene hearing these claims for well over 10 years, I have still yet to have seen any evdience in a very large club, or other clubs I've visited, that there is an inherent "problem".
I'm unclear why folks say this.

Simply because you have issues, does not imply that it's flawed or wrong.
You may want to try and keep trying to make sure you got the other thigns right before laying blame on the lights or a rule. You have to be able to produce a decent tank(reference or a control tank) and have mastery of CO2 and nutrients prior to light testing.

You will not find many experts suggesting that you need very high levels of light.
Generally the opposite.

Perhaps on a nano tank, say a 3 gallon tank.
But how to size a light bulb for those tanks using PC or normal FL's?
Hard to do.

But on 10 gallon to 300 gallon tanks?
Never seen an issue yet.

Disproven every comer also with a nice growth example.

I know light better than any of the models done up to correlate watts/lamp type and PAR etc.

I have a PAR meter and can drop it right on any plant I want to know about and see how it's doing.

That's far more powerful in comparisons than any model or method/rule etc.

Still, it also allows me to measure how much light comes from various set ups and what ligth intensities grow specific plants.

If you say it does not work, make a hypothesis, claim that "you cannot grow Glossostigma at 2 w.gal PC light in a 55 gallon tank can you?"

There, now you have something to test and see if you can disprove...........

Then you try to disprove that and see if you can get the weed to grow.

Step by step..........
If you disprove that, and then accept that it can be grown, then you move on to the next test subject, Rotala macrandra or whatever so called high light plant you want to grow.

If you have a PAr light meter witha water proof sensor, then you can also measure the PAR reading and use that as a future reference for any other tank, becuase now you know that you can grow HC or Gloss at 50 micromols/m^/sec.

The meter accounts for all the tank to tank, bulb to bulb, water transparancy differences, poor CO2, nutrient levels etc.

So you are looking at what can be done from there on if you have that much light(say 50micromols at the tip of the leaf) then you know you have enough light.

Does not matter what type of tank etc.

A bit more powerful than mere skeptisim and saying there are problems with something, it offers a solution and way to test it.

You might not have a PAr meter, they run 299$ of so for the Apogee which is not bad vs the accuracy and the cost for the LiCOR models.
I have and use both.

If not, see if you can do non limiting nutrients, non limiting CO2 levels and see.

Generally folks have issues with CO2 etc and that can lead to problems with growth that have less to do with the minimum light.

Read Tropica's article on CO2 and light.
It's a good little study.

Regards,
Tom BarrI think another issue many do not have access too perhaps because they have not had a need to test it, variable light intensity lighting.

I use both screening/shade cloth as well as moving the light farther/closer from the plants.
This way you can vary things and test such ideas.

It's really not hard and about the easiest stuff to test because the read out on light meters is very simple/easy.

Moving lights is also not hard, and at the lower ranges, growing plants and maintaining good CO2/nutrients becomes easier.

So try disproving things, try to see if you can disprove yourself.
Seem weird, but that is a good back door approach that can help you answer a lot.

Regards,
Tom Barr

[loaches r cool]

Tom, I'm not sure if your post was in response to me saying the wpg rule of thumb is ballpark only... I'm not trying to say what will grow what or such, but one cannot possibly say that it is very accurate. You can't disprove that watts isnt light as I am sure you know, and light efficiency varies greatly among the various types of lighting and different brand and spectrum of bulbs, as well as the use of reflectors and height, etc. I am sure there are many 2WPG setups out there that have more PAR hitting the plants than many 3WPG or 4WPG setups, even though many would want to argue that the bright 2WPG setup is actually much less that the others since. You can grow plants in a wide variety of lighting conditions, but its the "no 3wpg is not high light, it has to be 4wpg to be high" that I'm talking about mostly. I'm sure many would agree the lights I am setting up now, when all on, would probably fall into the high-light end even though they are only about 2.8wpg with all on (not that I will have to run all-on of course). But thats T5HO's each with Icecap SLR's, sitting over a 240g (~680W).