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

Hi George.

As a newbie I think I have a good perspective on this issue. 

I spent months prior to setting up my first planted tank reading APD, 
and the various planted tank websites.

One of my big concerns was getting unsightly algae.  The "experts" 
seemed to all say the same thing:  In order to get rid of and prevent 
algae, one should "crank the CO2".  Of course this comes as part of a 
larger prescription that there be no limiting nutrient but the primary 
point stressed again and again by these people is more CO2!

So, I did just that.  I cranked my CO2, killed three fish, backed off a 
bit, and now my plants pearl like mad every night during my 3 hour "noon 
burst" period of 4.5 WPG.

Also the algae has been kept at bay.  I even brought in a nasty case of 
hair algae from the LFS, and it hasn't been able to spread.

Yeah, my bigger fish are more lethargic than normal which does sort of 
bother me, and probably I'll back the CO2 off even more but I love 
seeing my plants pearl because it's an indicator that I'm actually 
succeeding at this planted tank thing that I've wanted to do for so long.

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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