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Too Much Light!


  1. Question about AHSupply Lighting
    by "George Booth" <booth/> (Mon, 16 Apr 2001)
  2. Re:400w over a 33 gal tank
    by "Robin Saunders Ryan" <rsaund/> (Sun, 19 Aug 2001)
  3. Metal Halide - can you have too much light ?
    by "David A. Youngker" <nestor10/> (Mon, 5 Feb 2001)
  4. (No Title)
    by Jon Hammond (Mon, 5 Feb 2001)

Question about AHSupply Lighting

by "George Booth" <booth/>
Date: Mon, 16 Apr 2001

>Date: Mon, 16 Apr 2001 09:00:38 -0600
>From: "Laura Czerwiec" <>
>Hello!  My name is Laura.  I've been lurking for awhile learning a lot of
>great stuff (thanks!), and now I have a question regarding the lights from
>AH Supply.  I have a 75 gallon tank, 48" long, which I've just set up.  I
>want a planted aquarium, and I'm wondering what my best choice for lights
>would be.  I am considering the 4x55 setup that AH Supply offers, would
>be adequate for my tank?  I was considering the 2x96 setup, but I don't
>think that this is enough light.  Please give me your ideas and

We have 4x55 on a 100 gallon tank and the light is MORE than adequate -
literally. I know everyone says "2-3 watts per gallon" is the minimum but
remember that thumb rule was developed back in the "old days" before good
quality lights and excellent reflectors were available (like those from AH
Supply). And, of course, everyone "knows" that more is better, so 4-5 watts
per gallon should be wonderful, right?

Wrong!  I would recommend no more than 150 watts of good quality light for
your 75. Three x 55 with one centered in the middle like:

           ================               ====================


Definitely go with AH Supply - one of the good guys in white hats.

Happy trails,

George Booth in Ft. Collins, CO (booth at frii dot com)
The web site for Aquatic Gardeners by Aquatic Gardeners

Re:400w over a 33 gal tank

by "Robin Saunders Ryan" <rsaund/>
Date: Sun, 19 Aug 2001

Hi Damian,

I have some first hand experience with this one! Dont do it!

I upgraded my tank from 55 gal to 120 gal, and went from 200 watts to 615.

I was really proud of the setup and thinking everything was going to be
great. I am finally done with my green water problems after buying a UV
sterilizer that I never needed on my 55. Also, I have decreased the wattage
from 615 to 440 (I have an expensive MH bulb that I don't even turn on!!)

at 440, everything grows great (1 foot growth of rotala indica in 8 days!)

Someone told me that having 615 watts on this system was like driving a
sports car really really fast. You can get great results but you can crash
very easily. One drop too much fert or one day behind on a water change and
the system goes haywire. Very unforgiving with that much light. I am very
happy with my 4 watts per gallon right now. I'm going to think long and hard
before I turn on that MH bulb again!


> Date: Sun, 19 Aug 2001 16:46:27 +1000
> From: Damian Barton and Jenine Plunkett <>
> Subject: Lighting options: 400W over a 33 gallon tank?
> Hi folks
> I have an approx 33 gallon tank (18inches high X 14inches wide X
> 36inches long) over which I have four 30wat flouroescent tubes that are
> now about 7months old. I'm not sure about tube costs in America but here
> in Australia the cheapest price on only just suitable tubes is $17.44
> per tube (brand; NEC GE Biolux) which means I'm looking at forking out
> $69.76 :  [ . On the other hand I have a HPS fixture and ballast that I
> could get a conversion lamp for (at a similar price with a colour
> temperature of 4000K). The thing is however that I can only use a
> 400wats lamp (it currently has a Son-T Agro 400wats bulb in it).
> I figured out that I would have approx 12 wats per gallon?
> Hmmmm is it just me or does that sound slightly ridiculous? *lol* I
> might be able to grow whatever I want with this setup but at the same
> time I'm thinking that that level of lighting is just plain wrong and
> something bad is going to happen- like an evil mutant strain of algae
> will take over!  Keeping up nutrient levels and Co2 would probably be
> crucial (and my crypts might not appreciate that amount of light) but
> are there any other factors I should consider? Should I abandon the idea
> or could it actually work?
> T.I.A.
> Damian (off to check out all the info on difficult high light demanding
> plants : )

Metal Halide - can you have too much light ?

by "David A. Youngker" <nestor10/>
Date: Mon, 5 Feb 2001

(No Title)

by Jon Hammond
Date: Mon, 5 Feb 2001

> My question to you is can you have too much light ?  My
> tank is 200 Litres and is a 3ft tank and the metal halides
> I can get are 175 watt or 250 watt for exactly the same
> price ? Will the 250 watt be overkill and are there ill
> effects from having heaps of light ?  What should I do
> get the 250w or 175w

You can definitely have too much intensity. Too much light can cause your
plants to believe they're at the surface, producing emergent growth patterns
while still 6-10 inches under water.

Why do I say this? When setting up one of my 55-gal Show tanks, I decided to
use 100 W Mercury Vapor lamps. While building the "hood" for them, I simply
sat the lamps, which were in reality $30 yard security lights, directly on
the tank top, about an inch- and- a- half from the water's surface. But I
left it there for a while when I started noticing certain changes in the
plant growth and wanted to observe further.

The tank itself was the one I placed in the Showcase section of the AGA's
IAS&C. The effects of the intensity can be seen in the set submitted. As I
wasn't planning on competing with the tank, I used it to demonstrate ways of
coping with "on-hand" situations while aquascaping (an in-depth article on
the tank is in the works). In the meantime, I still have a layout set up at
for visual reference to this text.

The Hygrophila difformis in the left rear corner refused to grow upright.
Instead, it began to simply carpet the tank bottom. This effectively crowded
growth up against the Ludwigia species, causing them to grow forward in an
arching curve, which helped to create some depth to the "grotto". I liked
that, so I kept it.

The Rotala macranda in the left front didn't used to be there. Limnophila
sessiliflora did. The intent was to blend one upright, larger leafed plant
into another more finely leafed one as you approached the front glass. But
the Ambulia would shift into emergent growth and flower while still six
inches under water. Made it look ragged as all get- out, so I replaced it
with a more light- loving plant.

The extra intensity also helped to keep the Cryptocoryne wendtii "brown" in
a ground- hugging mode rather than an upright forest. That was OK too,
considering its position.

The middle of the tank is covered with 24" Gro-Lux, so you have to move to
the right end f the tank for the othe MV.

Notice how _short_ the Cabomba caroliniana is? And still _flowering_?

Much above its present level and it would turn horizontal, as if trailing
the water's surface. And instead of the usual side shoots, it produced a
plethora of pad stalks. Hmm...not quite the effect I had intended. But I
discovered that if I kept it fairly short, I could get both fuller
_submersed_ growth behaviors *and* a pad stalk or two. So I timed one out to
bloom for the picture set.

On this side, you can see some more of the C.w. "brown" that _is_ growing
upright. It's a bit shaded by the Hygrophila polysperma "Rosanevig" (Sunset)
behind it.

The Echinodorus "Red Flame" to its immediate left, however, is under the
"blazing sun". Rather than "waste" any energy on large, lush growth, it
concentrates on sending out a constant stream of flower stalks.

That whole tank is completely refitted with 48" Gro-Lux now. As soon as the
growth patterns have finished shifting again and things are more
"normalized", a new set of photos will be taken for comparison.

As to the question of whether a 250 W Halide is too powerful for _your_
tank - well, to start, I'd guess that you aren't *about* to set the lamp
directly on the cover glass. So enough said on that.

But you will have to raise the lamp a good bit in order to get coverage
across a three- foot length, in which case you approach an old hydroponics
rule of thumb we used to use: "A foot on a side per 100 Watts". This
translates to 1000 W lamps covering a ten- foot square area, a 400 W to a
four- foot square, etc.

Setting a 250 W lamp high enough to get sufficient coverage should be just
about right for your tank. And you may have to live with a good deal of
"spillage", depending on hood/reflector design. (I tend to use spillage to
grow potted plants around the tank.)

Or you could concentrate the lighting from the 175 W to cover most of one
end of the tank, supplementing the other with a small fluoro or two for a
muted, "shaded" appearance and a tighter rein on spillage.

> Another concern of mine is its from a hydroponics shop
> and the tubes they come with are rated at 6200K.. is this
> ok for planted aquarium or do I want to try and see if I
> can find something closer to 5000 K ?

If it were me, I'd go with the 6200 K.

5000 K lamps are meant to come closer to "noonday" whiteness, but some
people still show a preference for "Ultra Daylight" type lamps in the
mid-6s. They report the 5s as still a little too "green" for their tastes.
So manufacturers blend in a little more blue and red to "offset" the green,
and this is good for the plants. The key is the "blend" of spectral spikes
they use to achieve the appearance of "whiteness". They aren't continual
spectrum- types of lamps, but cluster their output at specific wavelengths,
and if you vary the wavelength and intensity the combination shows  varying
degrees of "white".

The advantage of buying from a hydroponics store is that they normally have
the spectral charts available for each of their lamps. If you _can_ compare
the two, look for the one that puts out the highest combination of 420-440
nm and 610-660 nm - the blue and red portions. After that, it's more a
matter of your own personal preference as to output color "cast"...

- -Y-

David A. Youngker

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