High pressure CO2 pH swing

[inexorable]

I was curious for those of you out there with high tech planted tanks with apistos, how much pH swing do you allow in dosing CO2? and between what high and low? I don't have a computerized controller and I am worried that I may be having the pH fluctuate too much and consequently causing undue stress to my fish. I just purchased a pinpoint pH monitor. I don't have enough data yet to say what my average pH swing is. My old test kit was useless because the results were always below the range. Right now, its 6.2 with the CO2 off. Yesterday it was 5.9 with CO2 on.
Thanks,
Dave

 

[kingborris]

i use controllers on mine, but when i didnt, i used to get a 0.2 swing overnight (7.0-6.8)

do you run 24/7 or just with lights on? i found i got less of a swing running 24/7 and just running an air stone for a short while overnight, when the pH is at its lowest. this drives off a little CO2 and prevents the pH from dropping too low / the CO2 conc. getting too high. i also found this method better for plant growth compared to just running with the lights on, as the water is charged with CO2 all the time... you dont have a build up period when the lights / CO2 come back on in the morning

 

[farm41]

Dave,

What is your Kh?

Ph 5.9 sounds very low on a planted tank with co2, without suficient carbonate hardness, the tank could be headed for a PH crash.

 

[inexorable]

Kh

my KH is virtually zero. What is the optimal KH range for a planted apisto tank with CO2?

 

[farm41]

The Krib has some excellent material on co2 tanks. It is a must read for the begining planted tank hobbyist upgrading to co2.

Also an excellent reread for those of us who have not read it for a while.


http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html

http://www.thekrib.com/Plants/CO2/poison.html

http://www.thekrib.com/Plants/CO2/

Are you using tap or RO water? A Kh of 4-6 makes it real easy to inject co2, below that you get the Ph swings and eventually a crash. I would not even attempt co2 injection below 3 Kh without changing water very often, more than once per week.

 

[kingborris]

A Kh of 4-6 makes it real easy to inject co2, below that you get the Ph swings and eventually a crash. I would not even attempt co2 injection below 3 Kh without changing water very often, more than once per week.

i would agree. i run my discus tank at a KH of 4dKH, and my small planted tank at 5-6dKH. i have CO2 injection on both, and everything runs nice and steadily.

if your using RO water, and your tap water has some KH in, then you can mix some tap water in with RO to raise the KH of the mix.

If your tap has no KH, then you can add bicarbonate of soda to raise the KH and therefore pH of the water. alternatively, crushed cockle shells can also be used in a filter. these will slowly dissolve and provide a constant source of carbonates to buffer your water. you may need to play around with how much to add to your tank to get the balance you want.

HTH