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Re: [APD] How to make a good KH reference stock solution for CO2 measurement

On 12/14/06, Dennis Dietz <dennisdietz at verizon_net> wrote:
> As for an
> accurate solution, I am just trying to share some ideas to make this
> accessible/doable for more people.

Well, I think we should use an actual reference solution with a true
reference material then titrate it against the solution we make to find out
if the KH really is 4 or 5 or whatever.  :)

If I read everything right this is what I got from this string of posts.
Please correct me if I'm wrong.

Tom:  Crappy test kits can't be used to make a reference solution.  Weigh,
measure and dilute as needed to make a reference solution.
Vaughn:  The ballpark solution you get is good enough if you just use a
crappy test kit, so why bother.
Liz:  The two year old crappy test kit is as accurate as a home made
reference solution so why bother.
Tom:  With a reference solution you don't need a crappy test kit.
Dennis:  Making reference solutions requires equipment beyond the hobbyist
so why bother.  But hey, go for it if you wanna or spend your money on
something for the tank.

Of all these I guess I like Vaughn's the best because it gets to the point
that seems to be forgotten in all of this.  The target we're looking to hit
is pretty big.  Everyone says this -- there is a range of nutrients (and
whatever you call it, CO2 is just another nutrient) that works for
successful plant growth.  Suddenly it's like we want pinpoint accuracy for
CO2.  Okay, so why are the targets for NO3, PO4, K, Ca, Mg, Fe and trace so
danged big but the target for CO2 is so danged tiny?

Considering the fact that what we try to do with our aquariums is set up a
stable system, what's the deal with instant feedback anyway?  For people who
are adding CO2 via inline cannisters by means of a constant bubble rate,
what is the improvement of a 15 minute response time over a 2 hour reponse
time?  This is a set it and forget it method so where is the improvement?
Once you find the correct bubble rate there's no need to keep the drop
checker in the tank if your needle valve is decent, and if your needle valve
sucks you should have spent your money on that instead of a drop checker.

For people using a pH controller and injecting via diffuser, since the whole
goal is to define a pH as a shut off point, what improvement is there to get
a 15 minute response time verses a 2 hour response time?  It took 3 hours
for me to find the right pH set point, and I left the drop checker in for an
additional week just to assure that the setpoint was correct.  End of
additional equipment and worries -- the drop checker is now out of the tank
because its ony real use was to serve as a reference for calibrating the pH

It's not that I don't see the value of knowing that your CO2 is in the
correct range (unless, of course, you are a happy Luddite insistent on
measuring a healthy tank by how well it grows plants and how happy your fish
are) it's just that I don't see any value at all to putting out money and/or
effort to get instant feedback of a system that changes very slowly over

If you are going to be doing experimentation that requires instant feedback
there are already a number of CO2 probes on the market. For example:

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