Not too long ago there was a short discussion on the effectiveness (or
lack thereof) of these bulbs. For a recap do a google group search on
"Screw in fluorescent bulbs" One of the points that was brought up was
that the problem may be that the bulbs Richard used were soft whites
instead of 6500K bulbs. Since I have essentially the same setup that he
discussed in his post I decided to try some testing.

Today I went out to Home Depot and bought two 19W 6500K screw in
flourescent bulbs - sadly that seems to be the highest wattage you can
get for a 6500K bulb. What I had in my tank were two 3500K (soft white)
25W screw in flourescents. Since I wanted to see what the difference
would be I removed one of the 25W bulbs and replaced it with the 19W
6500K bulb. It is obviously closer to sunlight since one side of my
tank now has white light and the other has a yellow tint to it (just to
be clear, the side with the 3500K bulb is yellow). However to my eye
the new bulb looks quite a bit dimmer. I guess this is just the
difference between a 25W bulb and a 19W bulb showing up but I'm not
sure which one will be better in the long run.

So rather than going ahead and putting both 19W 6500K bulbs in like I
planned I've decided to leave it half and half for a few days just to
be sure this will be an improvement. For the next few days my tank will
have 19 watts of 6500K light on one side and 25 watts of standard soft
white (3500K) light on the other. As soon as I notice a significant
difference in plant growth (if I do) I'll report the results. I think
it will be interesting to see whether spectrum or total wattage is more
important to plants. Bets anyone?

-Daniel

dfreas wrote:
Not too long ago there was a short discussion on the effectiveness (or
lack thereof) of these bulbs. For a recap do a google group search on
"Screw in fluorescent bulbs" One of the points that was brought up was
that the problem may be that the bulbs Richard used were soft whites
instead of 6500K bulbs. Since I have essentially the same setup that he
discussed in his post I decided to try some testing.

Today I went out to Home Depot and bought two 19W 6500K screw in
flourescent bulbs - sadly that seems to be the highest wattage you can
get for a 6500K bulb. What I had in my tank were two 3500K (soft white)
25W screw in flourescents. Since I wanted to see what the difference
would be I removed one of the 25W bulbs and replaced it with the 19W
6500K bulb. It is obviously closer to sunlight since one side of my
tank now has white light and the other has a yellow tint to it (just to
be clear, the side with the 3500K bulb is yellow). However to my eye
the new bulb looks quite a bit dimmer. I guess this is just the
difference between a 25W bulb and a 19W bulb showing up but I'm not
sure which one will be better in the long run.

So rather than going ahead and putting both 19W 6500K bulbs in like I
planned I've decided to leave it half and half for a few days just to
be sure this will be an improvement. For the next few days my tank will
have 19 watts of 6500K light on one side and 25 watts of standard soft
white (3500K) light on the other. As soon as I notice a significant
difference in plant growth (if I do) I'll report the results. I think
it will be interesting to see whether spectrum or total wattage is more
important to plants. Bets anyone?

-Daniel

Not placing any bets but I'm very curious as to your results. Mine seem
to depend on the plant. I put a 14W 5500K compact screw-in in the hood
of my betta's 2 gallon tank instead of the sunlight I was using, moved
the tank out of the window, and switched the substrate to fluorite.
(The lighting change was because the stem plants were growing sideways
towards the window and I couldn't grow anything in the foreground.) The
previously slow-growing Rotala indica took off, and the foreground
banana lily is no longer losing leaves, but the Mayaca that was doing
very well is now dying. *scratches head*

--
__ Elaine T __
__' http://eethomp.com/fish.html '__

Let's assume for a moment spectrum doesn't matter and there's no great
difference between the worst (soft white) and best (triton) tubes. An
article in the kib says philips tested this and found a 10% difference
in plant growth from worst to best - insignficant.

Twenty years ago in these newsgroups people began talking about
different colors of light and how they affect plant growth. To
this day there is no such thing as the "right" spectrum. If there
was somehow it's evaded the notices of what much by now be millions
of aquarists over two decades. I can believe I'm this dumb but I
seriously dount the collected wisdom of all aquarists here is.

I doubt as well there's any question 80 watts of 2' fluorescent
will give better results than 20 watts of 2' fluorescent light.
Intensity matters.

In _The Optimum Aquarium_ Horst and Kipper note that "any fluorescent
tube light without a reflector should be rejected - 30% of the light
is wasted". Being a cylinder, there's no point in an equal distribution
of light pointing up as down into the tank henct the need for a reflector.

So, a 20W bulb putting out, as an examlpe 1000 lumens will only shine
700 lument into a tank and you'd need a larger than 20W tube w/o a
reflector to get as much light into the tank as a 20W tube with
a reflector.

Now, say you removed that 20W 2' light and put in a single 24watt
screwin in the middle of the tank. More watts, but a simple
test with a light meter in a plastic bag shows that at the ends
of the tank you don't have the same lux or lumens there as you
did with the 2' tube - the tube ligts evenly acros it's length,
the screwin blasts light in a radial pattern and all those spirals
casue strike back - light is bounced around everywhere losing energey
(dramatically) every time it bounces.

So, the problem with screwins is not really that they don't put out
much light, they do, but you just can't focus it and get it down to
the plants leaves very well.

Where screwins really shine (haha) is over small tanks where you can't
put a tube (Elaine, I doubt your Mayace problem is spectum; put the old
bulb back in and see what happens) but my opinion is because they
waste so much light you need to make a more or less continuos strip of
them, ie 4 of them to replace a 2' tube to get the same amount of light
*on the plant leaves" as you would with a 2' tube and at that point
you're wasting so much energy ($$$) and generating so much extra heat
that it seems to me like a very diminished return.





--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

Interesting. And almost certainly correct - I figured there was a loss
from the shape but didn't think it might be as significant as you
suggest. I think I will continue with the test for now just to see what
happens. I don't think I'm going to change to tube lighting - mostly
because I'm only growing low to mid light plants in this tank anyway
but I may start thinking about ways to modify my current setup to get
more of the light into the tank. Deffinately something to put some
thought into.

-Daniel

In article .com,
dfreas wrote:
Interesting. And almost certainly correct - I figured there was a loss
from the shape but didn't think it might be as significant as you
suggest. I think I will continue with the test for now just to see what
happens. I don't think I'm going to change to tube lighting - mostly
because I'm only growing low to mid light plants in this tank anyway
but I may start thinking about ways to modify my current setup to get
more of the light into the tank. Deffinately something to put some
thought into.

Well, it's a point source of light, not a strip, so, look to
exampled of other point sources of light. For example, metal halide
bulbs. They use either batwing reflectors or pendants.

I found some cheap ($1) reflectors at a salvage place. Combined
with cheap ($1) 11W screwins from "Dollorama" they make, well,
a reasonable $2 light for a small tank:

http://images.aquaria.net/hw/lights/pendants/cheap/

For screwins in incandescent fixtures about the best I could do
is use the heat and moisture resistant mylar from hydroponics.com
and these fixtures are on my daughters tanks that have crypts
and java fern:

http://images.aquaria.net/hw/lights/screwins/


--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

Well I think the results may be in for this test. I have explosive
growth on the 6500K side of the tank....and the same thing on the 3500K
side. I forgot that two days before I changed the lights I started C02
injection.

So what did I learn? Well if you have adequate light to begin with then
adding C02 is more effective than a 0.6 watt per gallon difference in
light. As evidenced by the fact that both sides of the tank are growing
at the same rate despite the light difference - obviously C02 was more
of a limiting factor for my tank than light. I'm going to leave it the
way it is for at least a week just to be absolutely sure but in the end
I think I'm just going to go with the light that looks better. That
would be the 6500K - I don't think it's any better for the plants, but
it does look more natural. The "soft whites" reflect off of some orange
rocks I have in the tank rather harshly because of their orange
tendancy.

-Daniel

In article .com,
dfreas wrote:
Well I think the results may be in for this test. I have explosive
growth on the 6500K side of the tank....and the same thing on the 3500K
side. I forgot that two days before I changed the lights I started C02
injection.

So what did I learn? Well if you have adequate light to begin with then
adding C02 is more effective than a 0.6 watt per gallon difference in
light. As evidenced by the fact that both sides of the tank are growing
at the same rate despite the light difference - obviously C02 was more
of a limiting factor for my tank than light. I'm going to leave it the
way it is for at least a week just to be absolutely sure but in the end
I think I'm just going to go with the light that looks better. That
would be the 6500K - I don't think it's any better for the plants, but
it does look more natural. The "soft whites" reflect off of some orange
rocks I have in the tank rather harshly because of their orange
tendancy.

Yup, this all sounds about what I'd expect. One thing soft whites are
good for is to make already red plants look much more red.

This works when you're eyeballing them in real life or in photos.
These for example were shot under 80W of CF warm white:

http://images.aquaria.net/plants/Hyg...sperma/sunset/

--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

Richard Sexton wrote:
In article .com,
dfreas wrote:

Well I think the results may be in for this test. I have explosive
growth on the 6500K side of the tank....and the same thing on the 3500K
side. I forgot that two days before I changed the lights I started C02
injection.

So what did I learn? Well if you have adequate light to begin with then
adding C02 is more effective than a 0.6 watt per gallon difference in
light. As evidenced by the fact that both sides of the tank are growing
at the same rate despite the light difference - obviously C02 was more
of a limiting factor for my tank than light. I'm going to leave it the
way it is for at least a week just to be absolutely sure but in the end
I think I'm just going to go with the light that looks better. That
would be the 6500K - I don't think it's any better for the plants, but
it does look more natural. The "soft whites" reflect off of some orange
rocks I have in the tank rather harshly because of their orange
tendancy.


Yup, this all sounds about what I'd expect. One thing soft whites are
good for is to make already red plants look much more red.

This works when you're eyeballing them in real life or in photos.
These for example were shot under 80W of CF warm white:

http://images.aquaria.net/plants/Hyg...sperma/sunset/

Nice shots. I wish I could get sunset hygro (or even regular hygro) in
Califonia, but it's an illegal noxious weed. *sigh*

--
__ Elaine T __
__' http://eethomp.com/fish.html '__

Very nice. I wish I could get my red plants to look as good. For some
reason the red plant I put in my tank immediately lost most of its red
and then stoped growing. Not that I have a ton of experience there -
I've tried two both of the same species (can't recall the name at the
moment). Neither died - they just refuse to grow. Some sort of red
sword plant - in fact it may have even been sold as "red sword."

-Daniel

In article . com,
dfreas wrote:
Very nice. I wish I could get my red plants to look as good. For some
reason the red plant I put in my tank immediately lost most of its red
and then stoped growing. Not that I have a ton of experience there -
I've tried two both of the same species (can't recall the name at the
moment). Neither died - they just refuse to grow. Some sort of red
sword plant - in fact it may have even been sold as "red sword."


A lot of things get sold as red swords. Some actually are swords;
I've seen lillies sold as "red swords".

Things that influence red in plants are bright light (the phots posted were
under 80W of compact fluorescent; the leaves were only 3-4" from the light)

Although, I get decent reds n Ludwigia repens with not much light -
plants are quite variable.

There is some chemistry to it, plants need nitrogen (and magnesium)
to make chlorophyl, so, low values in these two brings the red up.

--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

On 2005-03-05, dfreas wrote:
be clear, the side with the 3500K bulb is yellow). However to my eye
the new bulb looks quite a bit dimmer. I guess this is just the
difference between a 25W bulb and a 19W bulb showing up but I'm not
sure which one will be better in the long run.


The reason the soft white bulb seems brighter is because the spectrum
that it emits is more senstive to human eyes than the 6500K bulb.

--
"I have to decide between two equally frightening options.
If I wanted to do that, I'd vote." --Duckman

This is just plain wrong. The peak emission wavelength of a 3500K
blackbody is 828nm while the peak emission wavelength of a 6500K
blackbody is 445nm. The visible spectrum extends from approximately
400nm (violet) to 700nm (red) so 828nm would be outside the visible
spectrum in the infrared section while 445nm would be clearly visible.

Watt for watt a 6500K bulb will always appear brighter to the human eye
than a 3500K bulb. The *only* reason that the 6500K bulb looks dimmer
here is because it is 6 watts lower.

-Daniel