# [Wet Thumb Forum]-CO2 & blackwater



## rgrycki (Jun 13, 2005)

Ok, here's the things I know; Adding Co2 lowers pH, Blackwater extract, peat and wood also have the same effect. My KH is at 4 and pH is at 6.5 and according to the chart I have 12 ppm CO2. I know this is wrong because I don't add any. I do add black water extract so I know that is the reason for the lower pH. So here's my question: When and if I add CO2, will it drop my pH further, or will the blackwater have some sort of buffering capacity keeping the pH stable?


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## imported_russell (Sep 14, 2004)

is the balckwater necessary? i mean, if you add co2, can't you just quit dosing buffering stuff?

and by chuck gladd's co2 chart, a kh of 4 and a ph of 6.5 adds up to 37.9ppm co2. if you don't add any co2, then more than likely your co2 reading should be around 3ppm.


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## Hawkeye (Aug 20, 2004)

I used black water extract in a tank I had DIY CO2. The tank had a PH crash in a few weeks. If you need to use it I wouldn't use CO2. I am not sure I can explain why but I can tell you who to ask. Post the question to Roger. He told me once what happen but I don't remember what he said. All I remember is not to use black water extract with CO2 injection.

Hawk


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