[APD] Re: Co2 tubing and Light

[Wright Huntley <whuntley at verizon_net>]

Greetings, "New kid on the block..." [Have a real name?]

Glad to see someone who does not mind doing some homework.

> Message: 1
> Date: Thu, 18 Dec 2003 00:45:49 -0400
> From: Airwreck <Airwreck at airwreck_com>
> Subject: [APD] Co2 tubing and Light
> To: aquatic-plants at actwin_com
>
> Hi
>
> New kid on the block...
>
> two questions... I was catching up on this Co2 thing and tubing.. so what's 
> this big deal about co2 resistant tubing??? and why the concern???

Vinyl tubing, as used for regular airline has plasticizers that will 
interact with the CO2 with potentially undesirable consequences. Even if 
those don't add stuff you don't want to the aquarium, the erosion 
eventually hardens the tubing and may make it stiff and brittle over a 
long period of time. [I've never seen that, but it has been reported, I 
think.]

Silicone tubing has long been used in hospitals as it has less 
interactive chemistry, so is suitable for even oxygen as well as CO2 
lines. Unfortunately, it is more rubbery and stretchy, so must be 
attached to bayonet fittings with a wire tie, or it may blow off at 
pretty low pressures. It also makes distant needle valves tough to 
adjust, as the (slight) balloon must change size before the bubble rate 
changes. It is also pretty damned expensive!

I think some semi-rigid tubing, like Clippard's and refrigerator 
ice-maker line (polyethylene?) may be better for CO2 than vinyl, and way 
cheaper than silicone.

> the second is... does anybody have an answer to this
>
> I have been reading a lot about illumination and getting al kinds of info 
> lux, lumens,  PAR.
> doesn't anybody have a standard metering scale???
> when some one say Low light level or high light level... How many 
> foot-candles is that???

Doesn't matter much to the plants as foot-candles are based on the least 
useful spectrum for them, the human eye's response. Plants reflect away 
much of the green, which is weighted heavily, and need light in the red 
and blue that are given only about 10% weight in foot-candles.

I actually shop for fluorescent lamps with the *lowest* lumens ratings 
(per Watt), as that often indicates they have a broader spectrum of more 
use to the plants. Helps if the manufacturer gives a spectral 
distribution, but few do.

The Watts/gallon rules of thumb are based on the fact that the plants 
are more likely to be satisfied by that criteria than by one that is 
strongly biased against them (lumens, f-c, lux, etc.).

Plants have an action growth spectrum that is different for different 
plants, but chlorophyl A and B tend to give most of them big humps in 
the red and blue ends of the spectrum, so even a flat-spectrum standard, 
like PAR isn't too accurate for predicting growth potential.

Once you get it right, and get them enough of the light and other 
nutrients they like, what do they do? Some have the audacity to turn 
bright red, which would indicate they don't want what you just paid so 
much money to provide them!

Nature is inherently perverse, but particularly so in botany, I think!

Wright

--
Wright Huntley -- 760 872-3995 -- Rt. 001 Box K36, Bishop CA 93514

    "You will never understand bureaucracies until you understand that
for bureaucrats procedure is everything and outcomes are nothing. If
you have been living in a world where outcomes are everything, you may
have a very hard time understanding bureaucratic thinking or
practices."
     -- T. Sowell


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