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Re: [APD] Estimative Index for CO Dosing - Bah!

How can we tell that we have 20 ppm or 30 ppm or whatever CO2 
concentration, when the PH/KH/CO2 table isn't accurate due to other 
water parameters?  The advice to increase CO2 until the fish don't like 
it is just a way to find out how much we have, when no other way is 
available.   Of course if we had good test equipment available to 
accurately measure all water parameters, including CO2, we could use 
them and optimize everything.

Vaughn H.

On Wednesday, March 8, 2006, at 08:55 AM, gbooth at frii_com wrote:

> I keep seeing "good" advice here about setting CO2 levels.  "Keep 
> adding
> CO2 until the fish are distressed."  I know our main focus is plants 
> and
> the fish are merely decorative elements but don't you think this 
> treatment
> is a little harsh?
> If I were a newbie, I would interpret this advice along the lines of
> "There is a CO2 threshold [which may be different for different fish]. 
> If
> the CO2 is less than the threshold, everything is hunky-dory. If you go
> slightly above the threshold, the fish die. So stay just below the
> threshold and your plants will pearl like crazy and the fish will be 
> just
> fine."
> Anybody with a lick of common sense will realize that as CO2 rises, 
> fish
> will have more difficulty breathing.  Respiration is based on relative
> concentrations of gases. As CO2 concentration in the water increases, 
> CO2
> will leave the blood in the gills more slowly. As O2 in the water
> decreases, O2 will enter the blood via the gills more slowly.  Ever 
> hear
> of "Altitude Sickness"?  It affects different people in different ways.
> Some folks are fine on Rocky Mountain ski slopes, some people almost 
> die.
> An appropriate CO2 level is not a threshold, it's a compromise. 
> Increasing
> CO2 levels will makes the plants delirious but will affect fish more 
> and
> more.  If they are visibly distressed, it is way too high. It's like
> telling a college student "It's OK to drink but only until you pass 
> out."
> Oops, way too much.
> To the Sump Guy with the fast breathing discus and pearling plants: 
> think
> about it.
> A) Pearling plants -> High O2 -> Fish can inhale -> Good
> B) High CO2 -> Pearling plants -> Fish can't exhale -> Bad
> Hint: A and B don't cancel each other out.
> My experience indicates discus are more sensitive to CO2 levels than 
> other
> fish. We would never keep CO2 above 20 ppm in a discus tank. Or any of 
> our
> planted tanks, for that matter.
> 20 ppm not high enough to keep algae at bay?  Do the old fashioned 
> thing
> and get some algae eaters.  Make your tank a semblance of an eco-system
> rather than a large bottle of seltzer water.
> 20 ppm doesn't produce enough pearling?  So what?  See above.
> George in Ft. Collins, CO
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