Re: [APD] New Planted aquarium owner needs some advice

[Wright Huntley <whuntley at verizon_net>]

Tim Walker <twalker at swiftdsl_com.au> wrote:

> Hi Everyone,
>
> The quick question is I've added DIY CO2 to my tank last night and the pH
> has gone from 7.4 down to the lowest reading my pH test kit will read (6.0).
> What should I check/do?

The crucial balance for CO2 is the alkalinity of your water (known by 
the misleading and inaccurate term Carbonate Hardness -- KH).

If you assume most of the buffering in your water is 
carbonates/bicarbonates, you can get a good measure of the amount of CO2 
dissolved, by the charts (like in The Krib <www.thekrib.com>).

When KH is too low, you get the classic "pH Crash" which isn't all that 
bad until it gets so low your fish get real blood acidosis.

Later, you write:

> ... and the only test I ever did was for pH
> which usually prompted me to add chemicals.

Arghhhh! As Snoopy used to say.

pH kits have a high markup, and authors who understand no chemistry have 
written gobs of utter tripe about pH.

Can you feel the pH of the water when you go for a swim? Guess what! 
Neither can your fish. Between 4 and 10, they have no idea, and don't 
care what the pH is. [Much below and above, they can feel the burning 
damage.] pH shock is pure mythology, based on lack of understanding of 
osmotic adaptation and/or ammonium-ammonia conversion.

pH, when taken against KH, is a good indicator of how much acid (CO2, 
actually H2CO3?) you have added. The more KH, the more CO2 it takes to 
make pH drop a given amount.

Bottom line:

Get a KH kit and use that and pH to set the amount of bubbles of CO2 you 
put into your tank. It's actually really simple, when you catch on. If 
your KH is below about 2, add baking soda (plain old sodium bicarbonate) 
to bring it up to around 4-6 degrees. Then your CO2 won't push the pH 
nearly so low, so fast.

[Plants sometimes consume carbonates, so *always* make the KH test when 
using pH to set CO2 concentration.]

Wright

--
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
                    760 872-3995

        Eschew obfuscation and bloviation!


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