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[APD] Re: Co2 tubing and Light

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


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 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
     -- T. Sowell

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