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[APD] Re: Tiny bubbles or keeping the nutrients higher than needed

"Tom gives a compelling argument for using a fixed CO2 bubble rate
(without pH controller) in message
<http://fins.actwin.com/aquatic-plants/month.200201/msg00209.html> Once
you have established the steady state CO2 for a given pH and KH, you can
then keep that CO2 injection rate constant and ignore pH and KH from
that point on!!!"

Well, this assumes that the plant demand for CO2 and biomass is static.
It's not.

I think this is a damn good reason to have the nutrients and CO2 at excess levels rather than low just enough levels.

As plant biomass changes during the week/month/day even(some unit of time) the amount of nutrient demand also changes.

Make sense?
More plants = more nutrient uptake?

Well, this certainly applies to CO2 as well.
So while 20ppm might be fine with 50% less plant biomass, near the end when you know you need to prune, it's likely not enough and the level is less than before.

This is true for all the nutrients and the light to some degree.

This is one very good reason not to try _limiting_ nutrients with a moving target.
Having plenty means that the plants will not run out even after they double in size and need a good hacking.

This also shows the importance of consistent pruning and maintenance in terms of nutrients and algae(Caused by a lack of nutrients). 

"Most of the people who test for CO2 levels insist that there are too
many confounds to rely upon bubble rates. For those who consistently
achieve 20-40ppm CO2 by testing, what bubble rates do you need to
achieve your nominal CO2 level? What is your nominal CO2 level? For
those who use pH controllers, what bubble rate do you have during the ON
cycle and do you know the ratio of ON to OFF during the daytime hours?"

Oh I can do the bubble rate thing, but I like more precise and crical approaches to CO2 given it's prime importance at higher lighting, even low lighting.

I can watch the plants and knopw where I'm at, other folks can as well using just bubble rate, many are quite good at this. People can adjust this as the plant mbiomass increases and tend to watch their CO2 rate and the plant's response MORE.

Sometimes I will ignore the CO2 pH/KH level and add more CO2 if things justy don't look right.
Sometimes I will advise this to folks as well(rarely). If they are competent with CO2 and careful, they can do this.

But they should rule out other things first, nutrients are fairly easy to rule out with Estimative index methods.
>From there all that's really left in general maintenance and CO2.


Tom Barr

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