Re: [APD] CO2 takes awhile to make drop checker green

["S. Hieber" <shieber at yahoo_com>]

Certainly everything that effects CO2 shedding, absorbtion, etc can effect the level in the tank. Otoh, given enough parameters, the CO2 in the tank might never vary at all; it's the old Duhem-Quine thesis.

It's just that I wouldn't assume that a slow change in a closed ph tester separated from the tank water by a chamber of air, is an odditiy; it's what their famous for.

Someone already mentioned today a practical use for them as a one-time, or once-in awhile thing to establish a baseline. In that practice, the time lag isn't much of a problem.

If you want rapid reads, measure your tap water, measure you tank water, use an electronic meter.

sh 



----- Original Message ----
From: Mike Szilard <szilard at sbcglobal_net>
To: aquatic plants digest <aquatic-plants at actwin_com>
Sent: Wednesday, August 15, 2007 7:07:55 PM
Subject: Re: [APD] CO2 takes awhile to make drop checker green


On 8/15/2007 9:12 AM Dave Gomberg said the following:
> At 09:00 8/15/2007, aquatic-plants-request at actwin_com wrote:
>   
>> I'm going to guess not enough CO2?  2 bubbles per second isn't much for
>> a tank that size.    --Mike
>>
>>     
> I would propose this is due to a high kH and hence the ability to 
> take up a fair amount of CO2 before the pH changes much.   But I 
> could be wrong....
>
>
>
>   
Dave,
I thought that was the whole idea of the drop checker.  It has its own 
KH (usually 4 or 5 dKH) so that it isn't significant and there won't be 
a delayed response other than the previously mentioned transfer of CO2 
from tank water, to air in the drop checker, to the water in the drop 
checker.


For the other comment on 120bpm being plenty for a 100g tank, I'd say 
there are plenty of factors.  How efficient is the reactor?  How much 
surface disturbance is there to off-gas CO2?  How far is the drop 
checker from where CO2 is introduced into the tank?  Is there good even 
water movement so CO2 gets around the tank completely? 

At 2 bubbles per second it's entirely possible it takes that long for 
this particular tank to reach 30ppm of CO2.
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