WEIRD

[Angry_Platy]

I just measured my CO2 using a test kit and it measured 28ppm....slightly high but I just turned the lights on so not too concerned. I also measured my KH and GH....KH was 7.3 degrees....last week before adding CO2 my KH was 2.8 degrees.

So that tells me from the charts that my pH is approx. 6.9 (my test kit is dodgy so I don't use it)..I will take some water in to work tomorrow and test it using the real pH meter.

So what has happened then.....is my KH has risen with rising CO2 levels and the pH has stayed the same.....is this normal when you start using CO2?

I thought pH was meant to drop and KH stayed the same.....

WEIRD!!!!

EDIT.....all fish are acting normal

EDITED AGAIN....typed pH instead of CO2 in the first line )

 

[Silly me]

I just measured my pH using a test kit and it measured 28ppm....slightly high

I thought a PH of 14 was high

 

[Angry_Platy]

OOPS.....I meant to say my CO2 was 28ppm.....

EDITED

 

[Aulonochromis]

Actually 28ppm is just right. Alot of people aim for somewhere around the 30ppm mark.

 

[Angry_Platy]

Yeah, but what about the KH increasing but pH staying the same?

 

[Ann from Vermont]

I didn't know that there was a test kit to measue CO2. Who makes it?
Thanks
Ann from Vermont

 

[The Mohave Kid]

What you did not mention was your gH ??

If there is insoluble Calcium carbonate around it is buffering the acidic effect of the carbonic acid you are creating when you add carbon dioxide to the tank. The result .. the pH holds steady ... as carbonic acid reacts with Calcium carbonate it forms soluble Calcium Hydrogen Carbonate Ca(HCO3)2 and this is the source of your rising kH.

This is a good thing since it helps keep the pH stable ... in pure water kH and gH are zero and the pH could drop as low as 4.5 .. not good. Medium hard waters do have benafits.

Good Day ... B)

 

[Angry_Platy]

AH....that makes sense Mohave Kid....

So what could possibly be in my tank that contains insoluble calcium carbonate? I certainly haven't deliberately added it.....

 

[The Mohave Kid]

I was afraid you might ask that

I could only say that if you have Calcium ions ( gH) in the water from Calcium carbonate then some of this may be precipatating in the water ??? .. and going back into solution as you add C02 ??

CaCO3 (s) + H2O(l) + CO2(aq) <=> Ca2+ (aq) + 2HCO3-

Anything that reduces the CO2 will shift the above equation to the left and this is where you get the "insoluble" CaCO3 / Calcium carbonate even though you never added it yourslef ... it's most likely there if you have a gH >> 0. In the presense of increasing CO2 though CaCO3 reacts with the acid from H2O(l) + CO2 (aq) <=> H+ (aq) + HCO3- (aq) the carbonic acid reacts with the solid calcium carbonate.

Keep in mind even at maximum illumination and nutrients photosynthesis will max out at some concentration of CO2 ... so more is not always better ...

Here is a link you may have already seen .... keep in mind the table included in this link is for a "given kH" ... and no other acids.

http/www.aquariumsite.com/freshwater/chemistry.php#KHpH


Good Day ... B)