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Main
Date: 05 Mar 2005 10:55:02
From: dfreas
Subject: Testing screw in fluorescents
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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
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Date: 05 Apr 2005 18:12:52
From: dfreas
Subject: Re: Testing screw in fluorescents
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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
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Date: 04 Apr 2005 05:40:27
From: js1
Subject: Re: Testing screw in fluorescents
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On 2005-03-05, dfreas <dfrea001@odu.edu > 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
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Date: 24 Mar 2005 18:39:11
From: swint144
Subject: Re: Testing screw in fluorescents
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To solve the overheating problems in my rain-gutter strip, I painted
the gutter black (radiates heat better than white) and drilled 4 -
3/16" vent holes per 20W light. The vent holes are behind the
reflector, so no gets out. Stays warm, but no discoloration after 6 mo.
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Date: 08 Mar 2005 16:07:56
From: dfreas
Subject: Re: Testing screw in fluorescents
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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
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Date: 09 Mar 2005 04:28:06
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
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In article <1110326876.350231.74240@z14g2000cwz.googlegroups.com >,
dfreas <dfrea001@odu.edu > 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
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Date: 08 Mar 2005 04:07:00
From: dfreas
Subject: Re: Testing screw in fluorescents
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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
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Date: 08 Mar 2005 15:54:34
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
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In article <1110283620.698867.124220@o13g2000cwo.googlegroups.com >,
dfreas <dfrea001@odu.edu > 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/Hygrophilia/polysperma/sunset/
--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org
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Date: 08 Mar 2005 18:55:16
From: Elaine T
Subject: Re: Testing screw in fluorescents
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Richard Sexton wrote:
> In article <1110283620.698867.124220@o13g2000cwo.googlegroups.com>,
> dfreas <dfrea001@odu.edu> 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/Hygrophilia/polysperma/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 <'__><
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Date: 05 Mar 2005 17:34:10
From: dfreas
Subject: Re: Testing screw in fluorescents
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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
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Date: 06 Mar 2005 02:38:36
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
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In article <1110072850.630083.123230@f14g2000cwb.googlegroups.com >,
dfreas <dfrea001@odu.edu > 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
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Date: 06 Mar 2005 02:56:48
From: Charles
Subject: Re: Testing screw in fluorescents
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On Sun, 6 2005 02:38:36 GMT, richard@vrx.news (Richard Sexton)
wrote:
>In article <1110072850.630083.123230@f14g2000cwb.googlegroups.com>,
>dfreas <dfrea001@odu.edu> 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/
For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
parts, I like it so far.
--
Charles
Does not play well with others.
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Date: 06 Mar 2005 03:45:08
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
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>For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
>AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
>parts, I like it so far.
Seven watter per gallon ought to work :-)
I tried rain gutter too, white plastic stuff. The problem I had is the
heat from the lights (not insignificant) makes it hard, brittle
and over time turns the inside brown. I ened up grabbing a bunhc of
cheap incandescent hood from garage sales, they have a metal plate
to diddipate the heat. You can scavange a bit of the otherwise waster light
if you add some reflector material.
--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org
|
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Date: 06 Mar 2005 05:53:00
From: Charles
Subject: Re: Testing screw in fluorescents
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On Sun, 6 2005 03:45:08 GMT, richard@vrx.news (Richard Sexton)
wrote:
>>For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
>>AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
>>parts, I like it so far.
>
>Seven watter per gallon ought to work :-)
>
the watts per gallon does sound outrageous, but I don't see it as too
bright. In one tank some dwarf sagitaria does really well, in another
anubius grows about normally (slow), java moss survives, Echinodorus
tenellus barely lives and algae grows, but not too badly. There must
be a scale factor working here, but I don't understand it.
--
Charles
Does not play well with others.
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Date: 06 Mar 2005 18:26:11
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
|
In article <hc6l21pkufm9ot8b9agcn9dmc18pfrlhih@4ax.com >,
>the watts per gallon does sound outrageous, but I don't see it as too
>bright. In one tank some dwarf sagitaria does really well, in another
>anubius grows about normally (slow), java moss survives, Echinodorus
>tenellus barely lives and algae grows, but not too badly. There must
>be a scale factor working here, but I don't understand it.
Watts per gallon is a rough metric. Watts of energy going in
does not always produce the same lumens or lux (quantity) of
light coming out, and the shape of the bulb and and type or absence
or a reflector also matters.
What is significant is aht emount of light measured at the gravel.
And old photographic light meter in a plastic bag can measure this.
Small tanks and small bulbs are really a boundry condition for the
"watts per gallon" ruls and forumulas, especially imprecise ones
don't work well at boundry conditions.
Sounds fine to me.
--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org
|
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Date: 07 Mar 2005 04:23:13
From: Charles
Subject: Re: Testing screw in fluorescents
|
On Sun, 6 2005 18:26:11 GMT, richard@vrx.news (Richard Sexton)
wrote:
>In article <hc6l21pkufm9ot8b9agcn9dmc18pfrlhih@4ax.com>,
>>the watts per gallon does sound outrageous, but I don't see it as too
>>bright. In one tank some dwarf sagitaria does really well, in another
>>anubius grows about normally (slow), java moss survives, Echinodorus
>>tenellus barely lives and algae grows, but not too badly. There must
>>be a scale factor working here, but I don't understand it.
>
>Watts per gallon is a rough metric. Watts of energy going in
>does not always produce the same lumens or lux (quantity) of
>light coming out, and the shape of the bulb and and type or absence
>or a reflector also matters.
>
>What is significant is aht emount of light measured at the gravel.
>And old photographic light meter in a plastic bag can measure this.
>
>Small tanks and small bulbs are really a boundry condition for the
>"watts per gallon" ruls and forumulas, especially imprecise ones
>don't work well at boundry conditions.
>
>Sounds fine to me.
All good to me, but no way am I going to put my light meter in the
tank, plastic bag or no. I wonder why no one has yet built a light
meter with a submersible sensor. I'm happy with those lights on those
tanks, so I am not going to do anything about it anyway.
--
Charles
Does not play well with others.
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Date: 08 Mar 2005 03:54:51
From: Charles
Subject: Re: Testing screw in fluorescents
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On Mon, 07 2005 04:23:13 GMT, Charles <ckraft@SPAMTRAPwest.net >
wrote:
(snip)
> I wonder why no one has yet built a light
>meter with a submersible sensor.
I found out, they do. Got a Petsolutions catalog today, it fell open
at that page.
--
Charles
Does not play well with others.
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Date: 08 Mar 2005 05:48:50
From: Elaine T
Subject: Re: Testing screw in fluorescents
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Charles wrote:
> On Mon, 07 2005 04:23:13 GMT, Charles <ckraft@SPAMTRAPwest.net>
> wrote:
> (snip)
>
>
>> I wonder why no one has yet built a light
>>meter with a submersible sensor.
>
>
> I found out, they do. Got a Petsolutions catalog today, it fell open
> at that page.
Gotta love serendipity! If you get it, please share your results!
--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><
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Date: 08 Mar 2005 05:58:54
From: Charles
Subject: Re: Testing screw in fluorescents
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On Tue, 08 2005 05:48:50 GMT, Elaine T <eetmail-aquaria@yahoo.com >
wrote:
>Charles wrote:
>> On Mon, 07 2005 04:23:13 GMT, Charles <ckraft@SPAMTRAPwest.net>
>> wrote:
>> (snip)
>>
>>
>>> I wonder why no one has yet built a light
>>>meter with a submersible sensor.
>>
>>
>> I found out, they do. Got a Petsolutions catalog today, it fell open
>> at that page.
>
>Gotta love serendipity! If you get it, please share your results!
Probably won't. $102.99 US is a bit much for a toy that I wouldn't
use much. (not to say it would be the first.)
<:-)
--
Charles
Does not play well with others.
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Date: 06 Mar 2005 07:53:53
From: Elaine T
Subject: Re: Testing screw in fluorescents
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Charles wrote:
> On Sun, 6 2005 03:45:08 GMT, richard@vrx.news (Richard Sexton)
> wrote:
>
>
>>>For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
>>>AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
>>>parts, I like it so far.
>>
>>Seven watter per gallon ought to work :-)
>>
>
>
>
> the watts per gallon does sound outrageous, but I don't see it as too
> bright. In one tank some dwarf sagitaria does really well, in another
> anubius grows about normally (slow), java moss survives, Echinodorus
> tenellus barely lives and algae grows, but not too badly. There must
> be a scale factor working here, but I don't understand it.
Agreed. I'm getting Rotala indica growing about 1/2" a day on the 2
gallon tank with 14 watts but that's about like 2 wpg on a larger tank.
Many years ago, when small CF bulbs were not available I tried a 4
watt CF fixture designed for closets. That's 2 wpg, yet I could barely
keep Anubias alive.
I suspect that there is a minimum number of lumens required for aquatic
plant growth. In smaller tanks, we need more than 2 wpg to reach the
magic number.
--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><
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Date: 06 Mar 2005 05:34:11
From: Elaine T
Subject: Re: Testing screw in fluorescents
|
Richard Sexton wrote:
>>For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
>>AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
>>parts, I like it so far.
>
>
> Seven watter per gallon ought to work :-)
>
> I tried rain gutter too, white plastic stuff. The problem I had is the
> heat from the lights (not insignificant) makes it hard, brittle
> and over time turns the inside brown. I ened up grabbing a bunhc of
> cheap incandescent hood from garage sales, they have a metal plate
> to diddipate the heat. You can scavange a bit of the otherwise waster light
> if you add some reflector material.
>
I'm doing the same for my 2gal - using the incandescent hood that came
with the tank. I've got the fixture sitting on eggcrate so that the
tank evaporates more water to keep from overheating.
--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><
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Date: 06 Mar 2005 05:42:38
From: Charles
Subject: Re: Testing screw in fluorescents
|
On Sun, 06 2005 05:34:11 GMT, Elaine T <eetmail-aquaria@yahoo.com >
wrote:
>Richard Sexton wrote:
>>>For my 2.5 G tanks I use 13W bulbs. Each tank gets half of an
>>>AHSUPPLY 26 watt bright kit. I just build a new hood from rain gutter
>>>parts, I like it so far.
>>
>>
>> Seven watter per gallon ought to work :-)
>>
>> I tried rain gutter too, white plastic stuff. The problem I had is the
>> heat from the lights (not insignificant) makes it hard, brittle
>> and over time turns the inside brown. I ened up grabbing a bunhc of
>> cheap incandescent hood from garage sales, they have a metal plate
>> to diddipate the heat. You can scavange a bit of the otherwise waster light
>> if you add some reflector material.
>>
>I'm doing the same for my 2gal - using the incandescent hood that came
>with the tank. I've got the fixture sitting on eggcrate so that the
>tank evaporates more water to keep from overheating.
The incandescent hoods that came with my small tanks were pretty much
junk. The fluorescent lights melted holes in them.
the bright kit comes with a metal reflector, so I didn't need to do
anything there. I've only had the first one running for a week or so,
I'll wait to see how it works out. The plastic is PVC, so it will
probably get brittle over time, if too badly or not, we'll see.
--
Charles
Does not play well with others.
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Date: 05 Mar 2005 19:45:46
From: Elaine T
Subject: Re: Testing screw in fluorescents
|
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 <'__><
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Date: 05 Mar 2005 21:14:16
From: Richard Sexton
Subject: Re: Testing screw in fluorescents
|
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.
--
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http://www.mbz.org
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