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Re: [APD] Hair algae problem



Yes, it does rely upon KH and pH to determine the CO2 level.  The  
difference, and it is a very big difference, is how it does it.  The  
pH and KH being measured is not that of the tank water, but of the  
tiny bit of  water in the device's bulb.  We can use distilled water  
for that, with a tiny bit of bicarbonate of soda in it to set the KH  
where we want it.  And, that is the level where the indicator is  
green when the ppm of CO2 is what we want it to be.  This is  
important because it is relatively easy to see that the indicator is  
green, not yellow or blue.  When we measure pH of tank water, the  
color is often yellow to yellow green, an almost impossible color to  
be sure of.   By using distilled water with just bicarbonate in it,  
the pH/KH/CO2 relationship holds true - there are no other sources of  
acidity or alkalinity to upset that relationship.  In fact if you set  
the KH of the water at 4.0, which you can do very accurately, by  
using 4X the sample size and counting each drop of AP test kit KH  
reagent as .25 degrees KH, the indicator color will be green at 30  
ppm of CO2.  Or, if the KH is 5.0 degrees, it will be green at about  
40 ppm.  The margin of error for the 30 ppm reading, considering KH  
inaccuracy and indicator color ambiguities, is only about a  25 to 40  
ppm range, and with care, that can be greatly reduced.

So, these devices separate the measurement of CO2 in the tank water  
from any parameter of the tank water except the amount of CO2 in the  
tank water.  That is a major step towards accurate CO2 measurement.   
Just because it is simple, non-electronic, and an old device, does  
not keep this from being a great idea!   (It isn't my idea,  
incidentally, although I wish it were.  All I have done is recognize  
why it works, try it out, and publicize it.)

Vaughn H.

On Oct 16, 2006, at 4:41 AM, S. Hieber wrote:

> I'm pretty sure that this test still relies on the KH and pH to  
> determine CO2 and is subject to all the vagueries of such  
> measurements. Also, these tend to be very slow in reflecting  
> changes.  Basically, the color changes with changes in pH, based on  
> an established KH, this reflects the CO2 level. In fact even  
> themore expensive CO2 kits from HACH rely on KH and pH for  
> determining the CO2 level.
>
> IN effect, this *is* a pH test kit of sorts.
>
> sh
>
> * * * * * * * * *
> The aquatic plant convention is coming in November:
>
> http://www.aquatic-gardeners.org/convention.html
>
>
> ----- Original Message ----
> From: Vaughn Hopkins <hoppycalif at yahoo_com>
> To: aquatic plants digest <aquatic-plants at actwin_com>
> Sent: Sunday, October 15, 2006 10:41:55 PM
> Subject: Re: [APD] Hair algae problem
>
>
> Hi James,
> I'm going to guess that you are not using enough CO2.  Measuring the
> amount of CO2 in the water is not easy to do accurately.  But, there
> is now an easy way to do it and do it accurately.  See http://
> www.aquaticplantcentral.com/forumapc/do-it-yourself/32100-diy-drop-
> checker.html for details.  This allows you to accurately know that
> you have whatever ppm of CO2 you want in the water, without
> inaccuracies caused by having other sources of alkalinity and acidity
> in the water other than CO2.  And, it doesn't involve measuring pH in
> an area where a test kit isn't easy to read accurately, or with a
> probe which is subject to electric interference and calibration
> problems.  If you use this, at least you can eliminate low CO2 as a
> possible problem.  I started using this a week ago and it has worked
> like a charm!
>
> Vaughn H.
>
>
> On Oct 15, 2006, at 7:19 PM, James Foley wrote:
>
>> I have an aquarium with a sever hair algae problem. The algae in
>> question
>> forms very long strands, is bright green, and incredibly slimy when
>> trying
>> to remove it.
>> Here are the tank stats.
>> 77 gallon
>> 260 watts PC lighting
>> Eco-complete substrate
>> KH 3
>> pH 6.5
>> CO2 28ppm
>> Nitrate 15ppm
>> Ferts added: KNO3 1/2 tsp 3x per week, mono potassium phosphate 1/4
>> tsp 3x
>> per week, K2SO4 2 tsp 1x per week, MgSO4 3tsp 1x per week, calcium
>> chloride
>> 10 drops 1x per week.
>> Weekly 50% water change is done.
>> Plants include val spiralis, val americana, pygmy chain sword,
>> spade leaf,
>> ludwigia repens, and an amazon sword. Plant growth is phenominal
>> despite
>> algae.
>> Fish are 4 red belly piranha.
>>
>> So, what's the best way to deal with this algae? I'm considering
>> adding a
>> few amano shrimp to try out. I've tried a blakout when it was first
>> appearing with no effect.
>>
>> Regards,
>> James
>>
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>
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