This distrust of glass canopies seems like bunk

[Fjord]

okay, I hear that 1/4" of glass is bad when placed between your 4-5
watts per gallon lighting and your corals. It limits the transmittance
of the light spectrum, i hear.

However, when scuba diving I routinely see photosynthetic corals in 70
feet of water.

How can 1/4" of glass wreak more havoc than 70 feet of water?

Even admitting that 4-5 watts per gallon is not the same as sunlight,
how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?

- fjord

[Greg E.]

You lose 6-8% of the light from the two additional interfaces. Fused silica
(glass) doesn't absorb significantly at the wavelengths in question so it's
just the reflections that are an issue. It's not that it's "bad," but 6-8%
is not completely insignificant either, especially if you are trying to get
the most bang for your (electric bill) buck.



"Fjord" > wrote in message
oups.com...
> okay, I hear that 1/4" of glass is bad when placed between your 4-5
> watts per gallon lighting and your corals. It limits the transmittance
> of the light spectrum, i hear.
>
> However, when scuba diving I routinely see photosynthetic corals in 70
> feet of water.
>
> How can 1/4" of glass wreak more havoc than 70 feet of water?
>
> Even admitting that 4-5 watts per gallon is not the same as sunlight,
> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?
>
> - fjord
>

[Greg E.]

Another thing -- I was ignoring any losses due to "salt creep" and dirt on
the glass. That can easly cost you another 10-30% due to scatter and
reflection depending on the geometry.




"Fjord" > wrote in message
oups.com...
> okay, I hear that 1/4" of glass is bad when placed between your 4-5
> watts per gallon lighting and your corals. It limits the transmittance
> of the light spectrum, i hear.
>
> However, when scuba diving I routinely see photosynthetic corals in 70
> feet of water.
>
> How can 1/4" of glass wreak more havoc than 70 feet of water?
>
> Even admitting that 4-5 watts per gallon is not the same as sunlight,
> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?
>
> - fjord
>

[Michael Lawford]

But how much water would evaporate if the glass was not there.......?

So which is better no glass or glass?

~m

"Greg E." > wrote in message
...
> Another thing -- I was ignoring any losses due to "salt creep" and dirt on
> the glass. That can easly cost you another 10-30% due to scatter and
> reflection depending on the geometry.
>
>
>
>
> "Fjord" > wrote in message
> oups.com...
>> okay, I hear that 1/4" of glass is bad when placed between your 4-5
>> watts per gallon lighting and your corals. It limits the transmittance
>> of the light spectrum, i hear.
>>
>> However, when scuba diving I routinely see photosynthetic corals in 70
>> feet of water.
>>
>> How can 1/4" of glass wreak more havoc than 70 feet of water?
>>
>> Even admitting that 4-5 watts per gallon is not the same as sunlight,
>> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?
>>
>> - fjord
>>
>
>

[Pszemol]

"Michael Lawford" > wrote in message ...
> But how much water would evaporate if the glass was not there.......?

Evaporation is your friend. It helps you to cool the tank.
Replacing evaporated water is cheap when you use RO filter.

[Benjamin]

I have 110 watts of PC over my 10 gallon... and use a glass top which
*might* be 1/8th of an inch thick. I wouldn't care a bit to loose even 50%
of the light. Keeping the glass clean should help minimize the loss though.
I leave the plastic strip off the rear of the cover to get some air exchange
and haven't had any heat issues to mention. I think some loss of light is
worth keeping most of the dust out. Just my $.02

--
--



"Pszemol" > wrote in message
...
> "Michael Lawford" > wrote in message
> ...
>> But how much water would evaporate if the glass was not there.......?
>
> Evaporation is your friend. It helps you to cool the tank.
> Replacing evaporated water is cheap when you use RO filter.

[Don Geddis]

"Fjord" > wrote on 21 Aug 2005 22:4:
> okay, I hear that 1/4" of glass is bad when placed between your 4-5
> watts per gallon lighting and your corals. It limits the transmittance
> of the light spectrum, i hear.
> However, when scuba diving I routinely see photosynthetic corals in 70
> feet of water.
> How can 1/4" of glass wreak more havoc than 70 feet of water?
> Even admitting that 4-5 watts per gallon is not the same as sunlight,
> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?

Take a look at this recent article:
http://www.advancedaquarist.com/2005/8/lines
to see some lighting measurements in a tank, with and without covers, and
using artificial lights vs. the natural sun.

-- Don
__________________________________________________ _____________________________
Don Geddis http://reef.geddis.org/
The poor wish to be rich, the rich wish to be happy, the single wish to be
married, and the married wish to be dead. -- Ann Landers (1918-2002)

[Pszemol]

"Benjamin" > wrote in message ...
> I have 110 watts of PC over my 10 gallon... and use a glass top which
> *might* be 1/8th of an inch thick. I wouldn't care a bit to loose even 50%
> of the light. Keeping the glass clean should help minimize the loss though.
> I leave the plastic strip off the rear of the cover to get some air exchange
> and haven't had any heat issues to mention. I think some loss of light is
> worth keeping most of the dust out. Just my $.02

How often do you clean the top glass ?

What part of Globe do you live? Do you run a chiller ?

I have 2x 96W pc over 36"/30gallons tank and they warm the water alot.

[Benjamin]

> How often do you clean the top glass ?
2-3 times a weekish.
> What part of Globe do you live?
Iowa
>Do you run a chiller ?
No, my tanks are in my basement and I love AC. I have one dedicated vent in
my "office" where the 10 gallon is. The room is only 8x10. Stays quite
cool in there.

--
--
--


"Pszemol" > wrote in message
...
> "Benjamin" > wrote in message
> ...
>> I have 110 watts of PC over my 10 gallon... and use a glass top which
>> *might* be 1/8th of an inch thick. I wouldn't care a bit to loose even
>> 50% of the light. Keeping the glass clean should help minimize the loss
>> though. I leave the plastic strip off the rear of the cover to get some
>> air exchange and haven't had any heat issues to mention. I think some
>> loss of light is worth keeping most of the dust out. Just my $.02
>
>
>
> I have 2x 96W pc over 36"/30gallons tank and they warm the water alot.

[George Pontis]

In article >, gse1977
@comcast.net says...
> You lose 6-8% of the light from the two additional interfaces. Fused silica
> (glass) doesn't absorb significantly at the wavelengths in question so it's
> just the reflections that are an issue. It's not that it's "bad," but 6-8%
> is not completely insignificant either, especially if you are trying to get
> the most bang for your (electric bill) buck.

Minor quibble: fused silica is an exotic synthetic material, not the same as
"glass". It is closely related to quartz. Primary uses are in premium fiber optic
cables, lenses for high power lasers, and special applications that require
excellent clarity deep into the UV range.

[Marc Levenson]

Taking the glass tops off of your tank allows trapped heat to escape
more readily, and promotes better gas exchange at the surface of the
water. I've not used glass tops in 5 years, and I've never needed a
chiller.

Seeing how our lights will *never* come close to what the sun puts out,
I'm not willing to lose one iota of the lighting I pay for daily. If
these were double-ended MH bulbs (that require UV glass to protect from
burning the corals), I'd use those panels but still not have glass
covers on my own tanks.

Marc


Fjord wrote:
> okay, I hear that 1/4" of glass is bad when placed between your 4-5
> watts per gallon lighting and your corals. It limits the transmittance
> of the light spectrum, i hear.
>
> However, when scuba diving I routinely see photosynthetic corals in 70
> feet of water.
>
> How can 1/4" of glass wreak more havoc than 70 feet of water?
>
> Even admitting that 4-5 watts per gallon is not the same as sunlight,
> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?
>
> - fjord
>

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[Greg E.]

An entirely reasonable point, this was just the material I'm used to using.
Data for soda lime glass (the cheap stuff), borosilicate, alumina silicates
and other crown glasses is available, but much more of a pain to sort
through. Plus, fresnel reflection isn't a strong function of the material,
and even soda lime glass is good below 380 nm.


"George Pontis" > wrote in message
t...
> In article >,
gse1977
> @comcast.net says...
> > You lose 6-8% of the light from the two additional interfaces. Fused
silica
> > (glass) doesn't absorb significantly at the wavelengths in question so
it's
> > just the reflections that are an issue. It's not that it's "bad," but
6-8%
> > is not completely insignificant either, especially if you are trying to
get
> > the most bang for your (electric bill) buck.
>
> Minor quibble: fused silica is an exotic synthetic material, not the same
as
> "glass". It is closely related to quartz. Primary uses are in premium
fiber optic
> cables, lenses for high power lasers, and special applications that
require
> excellent clarity deep into the UV range.

[Benjamin]

Marc,

I recall reading that the gas exchange issue with glass tops was mostly bunk
and a non issue as gasses will seek sufficient equilibrium on their own.
They mention in fact it takes strong measures to stop them from doing so.
Anything more than just enough space to readily allow that is overkill. If
I recall one example used was a pinhole in the top of a can of pop... soda
still goes flat. Are you saying that isn't the case, or something along
those lines?

On the other hand I wouldn't suggest sealing the tops to the tank without a
skimmer either. I'm just not all convinced glass tops inhibit enough gas
exchange to matter all that much. If a little heat rise and minor light
loss isn't a problem for a particular situation, is there a problem at all?
Now plugging up the air intake on a skimmer, or not having one at all, that
would be a different matter. :-)

--
--



"Marc Levenson" > wrote in message
. ..
> Taking the glass tops off of your tank allows trapped heat to escape more
> readily, and promotes better gas exchange at the surface of the water.
> I've not used glass tops in 5 years, and I've never needed a chiller.
>
> Seeing how our lights will *never* come close to what the sun puts out,
> I'm not willing to lose one iota of the lighting I pay for daily. If
> these were double-ended MH bulbs (that require UV glass to protect from
> burning the corals), I'd use those panels but still not have glass covers
> on my own tanks.
>
> Marc
>
>
> Fjord wrote:
>> okay, I hear that 1/4" of glass is bad when placed between your 4-5
>> watts per gallon lighting and your corals. It limits the transmittance
>> of the light spectrum, i hear.
>>
>> However, when scuba diving I routinely see photosynthetic corals in 70
>> feet of water.
>>
>> How can 1/4" of glass wreak more havoc than 70 feet of water?
>>
>> Even admitting that 4-5 watts per gallon is not the same as sunlight,
>> how can 1/4" of glass be worse than 70 feet of water? or even 30 feet?
>>
>> - fjord
>>
>
> --
> Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
> Business Page: http://www.sparklingfloorservice.com
> Marine Hobbyist: http://www.melevsreef.com

[Marc Levenson]

I haven't read that it is bunk, but there always is something to debate
in this hobby, right? I don't really see how we can compare a soda can
with a pin hole, since that is a carbonated beverage. (Btw, why is it
that an un-opened 2-liter bottle goes flat if I buy quite bit in bulk
when there is a sale? *sigh* It seems only fresh and more expensive soda
tastes good.)

If you sit in your car with the windows cracked in a parking lot, you'll
not feel nearly as comfortable nor breathe as easily as you can with the
windows down. The breeze allows for better gas exchange. Same with our
tanks.

And I'm not willing to lose any of the lighting I'm paying for. The
ballasts, the bulbs, the reflectors and the electricity add up. Why
filter some of that away? What is the benefit?

Marc


Benjamin wrote:
> Marc,
>
> I recall reading that the gas exchange issue with glass tops was mostly bunk
> and a non issue as gasses will seek sufficient equilibrium on their own.
> They mention in fact it takes strong measures to stop them from doing so.
> Anything more than just enough space to readily allow that is overkill. If
> I recall one example used was a pinhole in the top of a can of pop... soda
> still goes flat. Are you saying that isn't the case, or something along
> those lines?
>
> On the other hand I wouldn't suggest sealing the tops to the tank without a
> skimmer either. I'm just not all convinced glass tops inhibit enough gas
> exchange to matter all that much. If a little heat rise and minor light
> loss isn't a problem for a particular situation, is there a problem at all?
> Now plugging up the air intake on a skimmer, or not having one at all, that
> would be a different matter. :-)
>

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[Fjord]

> Seeing how our lights will *never* come close to what the sun puts out,

It's a manner of magnitude. you can certainly put enough lights over
the tank that you'll be surpassing sunlight illumination.

I want to thank Don Geddis for the article at:
http://www.advancedaquarist.co m/2005/8/lines

There's some good info in there, but most importantly it led to this
article:
http://www.advancedaquarist.co m/2005/8/lines

A table towards the end of the article allows me to estimate the amount
of light I was seeing at around 70 feet. His table "only" goes to 20
meters or nearly 66 feet, which would be a PAR reading of 160-190
depending on the type of reef environment we're speaking of.
Incidentally, this is nearly a 10-fold reduction from the amount of
light seen in 1-2 meters of water, even though I've seen some of the
same species at both depths (mostly brain corals, mind you, elkhorn
types seem to have tapered off).

The tank readings from this second article had a pretty big variation
on PAR, yet all of the corals seemed healthy (this is an assumption I'm
making, though). These ranges were often higher than 160-190 PAR and
also often less than that.

I'm not seeing anything that says "no don't use a glass hood". It
looks like this will be a trade off between 1) light intensity needed
2) evaporation and 3) heat.

80 watts of CF 3-4 inches over a 10 gallon tank should be plenty of
light even with a glass hood whether it removes 6-8% or 30% of the
light. I do see Marc's point about the money to generate that amount of
light being wasted, however.

--
Fjord

[David Zopf]

"Marc Levenson" > wrote in message
...
>I haven't read that it is bunk, but there always is something to debate in
>this hobby, right? I don't really see how we can compare a soda can with
>a pin hole, since that is a carbonated beverage. (Btw, why is it that an
>un-opened 2-liter bottle goes flat if I buy quite bit in bulk when there is
>a sale? *sigh* It seems only fresh and more expensive soda tastes good.)
>
First post to this newsgroup. Hello to all... New to the aquarist's
hobby, but a ploymer chemist by trade. I'm just lurking and learning for
the most part... but I can answer this. The plastic used to make a soda
bottle (PET) is an inefficient, imperfect gas barrier. Soda is bottled
pressurized with carbonation (CO2), so equilibrium favors the gradual escape
of CO2, some at the threads of the bottle opening, but a significant amount
is also lost directly through the soda bottle wall. This is a primary
reason why soda in aluminum cans has more "fizz". So grab the 24-pack when
it goes on sale, and hope those geeky polymer chemists make a better 2Liter
sometime soon...

Regards,
DaveZ
Atom Weaver

[Benjamin]

Marc,

It is amazing anyone can keep a tank running with all the various debates.
I hear what your saying though, and follow the logic, just not sure of the
actual facts is all. I was just commenting on what I had seen elsewhere.
I hope I wasn't taken as implying that I thought all of it was in fact bunk?
I meant only that I heard it was bunk. I certainly wasn't trying to come
across that running without tops is a bad thing, but point out what I had
heard and what I had noticed. I also saw somewhere some calculations of
skimmer bubble surface area. Wow, that was some serious surface area.

Maybe somewhere there is something related to dust effects and whatnot, but
I haven't gotten that far. For all I know any semi decent skimmer should
have no problem pulling all the dust out, then again what I don't know is
more than I do know.

As for filtering the light... I had a set of 55watt PCs, tossed em on the 10
gallon... loosing a little in my case isn't an issue, nor can I say loosing
a little is a benefit either, it's just what I had available.

--
--


"Marc Levenson" > wrote in message
...
>I haven't read that it is bunk, but there always is something to debate in
>this hobby, right? I don't really see how we can compare a soda can with
>a pin hole, since that is a carbonated beverage. (Btw, why is it that an
>un-opened 2-liter bottle goes flat if I buy quite bit in bulk when there is
>a sale? *sigh* It seems only fresh and more expensive soda tastes good.)
>
> If you sit in your car with the windows cracked in a parking lot, you'll
> not feel nearly as comfortable nor breathe as easily as you can with the
> windows down. The breeze allows for better gas exchange. Same with our
> tanks.
>
> And I'm not willing to lose any of the lighting I'm paying for. The
> ballasts, the bulbs, the reflectors and the electricity add up. Why
> filter some of that away? What is the benefit?
>
> Marc
>
>
> Benjamin wrote:
>> Marc,
>>
>> I recall reading that the gas exchange issue with glass tops was mostly
>> bunk and a non issue as gasses will seek sufficient equilibrium on their
>> own. They mention in fact it takes strong measures to stop them from
>> doing so. Anything more than just enough space to readily allow that is
>> overkill. If I recall one example used was a pinhole in the top of a can
>> of pop... soda still goes flat. Are you saying that isn't the case, or
>> something along those lines?
>>
>> On the other hand I wouldn't suggest sealing the tops to the tank without
>> a skimmer either. I'm just not all convinced glass tops inhibit enough
>> gas exchange to matter all that much. If a little heat rise and minor
>> light loss isn't a problem for a particular situation, is there a problem
>> at all? Now plugging up the air intake on a skimmer, or not having one at
>> all, that would be a different matter. :-)
>>
>
> --
> Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
> Business Page: http://www.sparklingfloorservice.com
> Marine Hobbyist: http://www.melevsreef.com

[Marc Levenson]

Thanks Dave.... your last name is German. Are you in the U.S. or
posting from Europe? Zopf is one of my favorite breads that I ate in
Switzerland.

Marc


David Zopf wrote:
> "Marc Levenson" > wrote in message
> ...
>
>>I haven't read that it is bunk, but there always is something to debate in
>>this hobby, right? I don't really see how we can compare a soda can with
>>a pin hole, since that is a carbonated beverage. (Btw, why is it that an
>>un-opened 2-liter bottle goes flat if I buy quite bit in bulk when there is
>>a sale? *sigh* It seems only fresh and more expensive soda tastes good.)
>>
>
> First post to this newsgroup. Hello to all... New to the aquarist's
> hobby, but a ploymer chemist by trade. I'm just lurking and learning for
> the most part... but I can answer this. The plastic used to make a soda
> bottle (PET) is an inefficient, imperfect gas barrier. Soda is bottled
> pressurized with carbonation (CO2), so equilibrium favors the gradual escape
> of CO2, some at the threads of the bottle opening, but a significant amount
> is also lost directly through the soda bottle wall. This is a primary
> reason why soda in aluminum cans has more "fizz". So grab the 24-pack when
> it goes on sale, and hope those geeky polymer chemists make a better 2Liter
> sometime soon...
>
> Regards,
> DaveZ
> Atom Weaver
>
>
>

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[Marc Levenson]

No worries, Benjamin. I'm really not into heated debates anyway. Too
many people hope to just get a reasonable answer to their questions, and
I try to help when I can.

My 280g is open top. I've not even gotten the woodwork done around the
top of the tank, and it has been running for a year this month. The
surface of the tank drains into two large overflows, and these drain
down into the skimmer section of my sump where a large quality skimmer
is pulling out all it can daily. Dust is definitely being exported,
along with other vile stuff. Let me find you a picture of some recent DOCs.

http://melevsreef.com/pics/0805/skimmate_12hrs_b.jpg (Enjoy.) ;)

I used to have 3 x 55w PC bulbs over my 29g and it again was without
glass although Hamilton was adament that I keep the barrier there to
avoid moisture entering the endcaps. I didn't follow those directions,
and my tank never had heat issues. I did have condensation in the
winter months that caused me some trouble, but I worked around that as
best I could.

Marc


Benjamin wrote:
> Marc,
>
> It is amazing anyone can keep a tank running with all the various debates.
> I hear what your saying though, and follow the logic, just not sure of the
> actual facts is all. I was just commenting on what I had seen elsewhere.
> I hope I wasn't taken as implying that I thought all of it was in fact bunk?
> I meant only that I heard it was bunk. I certainly wasn't trying to come
> across that running without tops is a bad thing, but point out what I had
> heard and what I had noticed. I also saw somewhere some calculations of
> skimmer bubble surface area. Wow, that was some serious surface area.
>
> Maybe somewhere there is something related to dust effects and whatnot, but
> I haven't gotten that far. For all I know any semi decent skimmer should
> have no problem pulling all the dust out, then again what I don't know is
> more than I do know.
>
> As for filtering the light... I had a set of 55watt PCs, tossed em on the 10
> gallon... loosing a little in my case isn't an issue, nor can I say loosing
> a little is a benefit either, it's just what I had available.
>

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[David Zopf]

"Marc Levenson" > wrote in message
...
> Thanks Dave.... your last name is German. Are you in the U.S. or posting
> from Europe? Zopf is one of my favorite breads that I ate in Switzerland.
>
I'm a US mutt of German(mostly)/English/Scottish descent, living in
northwestern Connecticut.

I didn't know it was a Swiss baked good. I only knew that the German
translation was "braid"... There, it refers to hair ornamentation...
Perhaps your favorite bread was some sort of a twisted-braided variety?

(Sorry for the OT, everyone else, I have not-much of value to contribute
on the subject of aquaria, aside from possibly conjecture on general science
aspects of the hobby..)

Regards,
DaveZ
Atom Weaver
Damned Yankee ...aber ich kann doch ein bisschen Deutsch sprechen und
screiben.

[Marc Levenson]

Yes, a Zopf is a loaf of braid that looks braided. Let me see if I can
find you a picture.

http://www.dianasdesserts.com/index.cfm/fuseaction/recipes.recipeListing/filter/dianas/recipeID/756/Recipe.cfm
http://www.about.ch/culture/food/zopf.html

Gotta love Google.

Marc


David Zopf wrote:
> "Marc Levenson" > wrote in message
> ...
>
>>Thanks Dave.... your last name is German. Are you in the U.S. or posting
>>from Europe? Zopf is one of my favorite breads that I ate in Switzerland.
>>
>
> I'm a US mutt of German(mostly)/English/Scottish descent, living in
> northwestern Connecticut.
>
> I didn't know it was a Swiss baked good. I only knew that the German
> translation was "braid"... There, it refers to hair ornamentation...
> Perhaps your favorite bread was some sort of a twisted-braided variety?
>
> (Sorry for the OT, everyone else, I have not-much of value to contribute
> on the subject of aquaria, aside from possibly conjecture on general science
> aspects of the hobby..)
>
> Regards,
> DaveZ
> Atom Weaver
> Damned Yankee ...aber ich kann doch ein bisschen Deutsch sprechen und
> screiben.
>
>

--
Personal Page: http://www.sparklingfloorservice.com/oanda/index.html
Business Page: http://www.sparklingfloorservice.com
Marine Hobbyist: http://www.melevsreef.com

[David Zopf]

"Marc Levenson" > wrote in message
m...
> Yes, a Zopf is a loaf of bread that looks braided. Let me see if I can
> find you a picture.
>
> http://www.dianasdesserts.com/index.cfm/fuseaction/recipes.recipeListing/filter/dianas/recipeID/756/Recipe.cfm
> http://www.about.ch/culture/food/zopf.html
>
> Gotta love Google.
>

Outstanding! Thanks for that...

I'm reminded of the immortal words of JFK "Ich bin ein Berliner auch!"

;-) At least I get to be a loaf of bread, instead of a donut...

Regards
DaveZ
Atom Weaver