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RE: Estimative method/Barr method


Thanks for the input.  Over the past two years I have gradually adopted
most of the recommendations you and others have made here in APD.  Many
of your comments have really helped me "see the light" about what is
going on.  I really appreciate the help.  It has made this much more fun
and interesting.

Although there are some differences in method expressed here, there are
some things I have heard from many.  One thing that stands out in my
mind is trying to keep the tank conditions relatively stable (I realize
within limits).  This is what concerns me about the water change regimen
you recommend.  The basic premise of resetting the tank every week (when
you are dosing the nutrients in sufficient quantities so that there are
no nutrient deficiencies and not doing extensive testing) makes a whole
lot of sense.  What I am wondering about is my specific situation.  

With high GH and KH and pH tap water, a 40-60% water change is taking my
CO2 down to around 5 ppm (or whatever normal ppm is without supplement).
It takes about 1-2 days (sometimes more) for the pH to recover to the
7.1-7.3 range I try to keep it in.  With my previous water change
regimen of every 2-4 weeks a 2 day drop in CO2 (rise in pH) did not seem
too bad (only 5-10% of the time).  With a weekly water change it will
now be for about 30-35% of the time or more.  This means the CO2
concentration is moving to around 5 ppm for around a third of the time.
Occasionally I might have to do a water change after only 4 days because
of other obligations (yes there are other things besides fish and plants
though my wife might suggest I think otherwise - however I do enjoy this
a lot) and that could mean the CO2 level might be down below 10 for
quite a while.  If I had to change water after 4 days twice or more in a
row the tank would have the desired CO2 level for only 20-25% of the
time.  That would almost be the same as not having CO2.  In a high light
tank this would seem to me to be a bad thing.  From what you have said
about CO2 and algae, I could imagine this being a really bad deal with a
lot of light.  As I recall from my early days at plants 

Since you and apparently many others are doing this with success I
assume one or more of the following:

1)  It is not a bad deal.  I know, the plants adapt and with the right
nutrient levels it will all work out without a lot of algae.  The key is
getting the nutrients right, the low CO2 levels will just slow plant
growth for those periods it is down.

2)  Your CO2 system returns to the desired value much quicker than mine.
This would make me think there is something wrong with my CO2 system:
the reactor needs cleaning more often than I am doing it; the water flow
is too high for good exchange; and/or the water flow is too low to pump
enough CO2 into the tank.  I know that everyone's circumstances are
different (tap water GH, KH, pH, and w/g, fish and plant load and needs,
etc.) but I suspect that this is probably where my tank differs from
most of yours and is the area I should look into first.  After you do a
50% water change, how high does your pH go and how long does it take
your tank to come back to the desired pH?

3)  I should make the water I add during a water change more like the
water in the tank (something like add CO2).  It seems logical to make
the water you add as close to the water in the tank as possible.  But I
have never seen mention of that here and judging by the 'minimum effort
to get great results' attitude many here seem to have I would suspect
that either this is not the case or it is such a given no one talks
about it any more.  Is it worth adding CO2 to the change water?  This
seems like a bit much but it would not be hard to add a tee and a
reactor (have an extra one) to the closed container I use to mix change
water.  Do you add something else for pH?  Wouldn't that affect the
pH-KH table?  That also seems to contradict about everything I have seen

Oh well.  I remember the days when I first started doing this and the
various algae I learned to beat.  Most victories were with good CO2
levels (thanks to you Tom for that lesson!) and proper fertilizer.   I
realize that as I try to add nutrients via the Barr method I will
probably over and under dose until I get it right.  I would think this
would be the case even with testing as I would have to learn about the
uptake rate too.  With low CO2 levels for extended periods I have
visions of furry coverings on the glass, threads running everywhere,
chocolate brown coated plants and fuzzy little green growths everywhere.
That stuff was no fun the first time and my wife almost got to the point
where I could not have it in the house.  I really do not want to fight
that battle again - either one of them.

Charles Kuehnl


> -----Original Message-----
> From: Thomas Barr [mailto:tcbiii at earthlink_net]
> Sent: Thursday, April 03, 2003 12:07 AM
> To: ckuehnl at cox_net; Aquatic-Plants at actwin_com
> Subject: Estimative method/Barr method
> http://www.aquatic-plants.org/fert/est_index/est_index1.html
> This gives a bit more in depth discussion of it.
> In a nutshell: you maintain a stable level of nutrients by doing large
> weekly waters that prevents anything from becoming to high/in excess
> dosing every week to up to 3-4x a week(depending on light
> biomass) to make sure nothing runs out and causes a deficiency.
> Using the nutrients listed: it's cheap, requires only testing for CO2,
> basic aquarium maintenance skills to deal with plant health.
> Regards,
> Tom Barr