Re: Low Light, Slow Grow Tank

["S. Hieber" <shieber at yahoo_com>]

Kirk Melton asked if his tanks would be considered High
light or low light level tanks:

>  . . . at what point does a low light tank
> become a high light 
> tank?  

There is no threshold value that counts as *the point*
where one crosses over.  It's a continuum.  At what point
does the rainbow turn red.  There is no *point* but it's
generally about here . . .

The answer will vary too according to who is answering, as
there is some disagreement over how much light is optimum
for most commonly used plants with/without added nutrients,
including CO2.

But *generally speaking*, below 2 wpg is on the low side of
the (somewhat fancifully speaking) dichotomy.  Above that,
you're on the high side.  With PCs and very good reflectors
you can get the same results at 2 wpg as with straight tube
fluorescents and not-so-hot reflectors running at 4 wpg.

The recent issue of The Aquatic Gardener replays several
APD posts on this very subject and you might find that a
convenient place to review the topic.

http://www.aquatic-gardeners.org/tag.html

Or you could peruse the APD archives for the very same info
-- but much less convenient.

> The 72 currently has 80 watts, and you are
> suggesting one more 40 
> watt.

Anyway you cut it, this is a pretty low light tank, even
with the added 40 watts.

>  My 75 at home has 130 watts of CF lighting, and
> one 40 watt 
> fluorescent strip (sometimes I leave it off).  

Well, this one is moving closer to the high side, but not
much if you're leaving the 40 watts off sometimes.


> Would the
> tank at home be 
> considered high light due to the CF bulbs (which only
> seem to focus light 
> over the back of the tank (it's a Custom Sea Life
> Brite-Lite strip with 
> 6700K bulbs), or is it still a low light tank?

I don't think this tank is going to be a speed demon but it
can certainly grow more kinds of plants than the other --
especially since the PC light is concentrated.  It would
probably be easier to manage with added CO2 and other
nutrients accordingly at this light level (if you leave the
40 watts on with the others) than without the added CO2 and
nutrients but you could probably pull it off either way. 
So I'd mark it on the high side of inbetweener.

Scott H.

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