co2 saturation

[dazzer1975]

I got my pressurised system and have recorded a kh of 4.5 degrees hardness, ph of 6.8 which gives me a co2 level of 21 ppm. This is taken just before the lights go out after 12 hours being on, the lighting level is 130 watts over 40 uk gallons.

I was wondering though, if there is an upper co2 level that the water simply cannot take in any more co2 or wether, if you could set up a reactor while pumping in enough co2 would the levels just keep on rising and rising?

 

[quenton]

Re: co2 saturation

I got my pressurised system and have recorded a kh of 4.5 degrees hardness, ph of 6.8 which gives me a co2 level of 21 ppm. This is taken just before the lights go out after 12 hours being on, the lighting level is 130 watts over 40 uk gallons.

I was wondering though, if there is an upper co2 level that the water simply cannot take in any more co2 or wether, if you could set up a reactor while pumping in enough co2 would the levels just keep on rising and rising?

At some point your fish would all die. I suspect you might run into a limit based on whatever diffusion system you are using -- but certainly there has to be a limit at which the water would not hold any more.

On the topic of your 21ppm -- if I believed my pH and kh values, I would have
about 60ppm CO2 and my fish would all be dead. I then did a pH - pH test and came up with lots less than 30ppm.

I would try that and see what you get -- do a pH test of the tank water, then take a quart of the tank water and let sit out for 24h and measure that. For about 30ppm CO2 you would expect about a 1.0 diff in the pH values. I don't know the exact formula -- it might be on this site somewhere, not sure, but the recommendation I believe is between 1.0 and 1.1 difference.

 

[dazzer1975]

Re: co2 saturation

Cheers Quenton,

Before I introduced the co2 system I had a p.h of 6.8 and a kh of 30 - 40 ppm which equates to roughly 2 degrees hardness, I increased the hardness using bicarbonate of soda and now have a kh of 80ppm which equates to 4.5 degrees of carbonate hardness and my p.h. is still 6.8 after the introduction of co2. I used this calculator http://www.dataguru.org/misc/aquarium/calKH.asp to determine how much bicarbonate of soda to use which states that I would have seen a 0.69 - 0.98 p.h. increase after the addition of the bicarbonate of soda.

I have yet to do a degassed ph test but I will take some water out now to test tomorrow,

Thanks a lot quenton,

Much appreciated

 

[Tom Barr]

Re: co2 saturation

Yes, the KH is playing with you, I'd niot mess with the KH, add enough CO2 to knock the pH to about 5.8-6.0 range, observe plants and fish, you can still add baking soda if you want to raise the pH and KH up to say 6.4 and 4 etc or close to that. The KH seems to be off by about .2-.4 degrees.

Regards,
Tom Barr