pH controller and buffering - The Planted Tank Forum
 
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post #1 of 8 (permalink) Old 09-07-2011, 04:16 AM Thread Starter
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pH controller and buffering

I, like another member of the forum, have absurdly low kh .. testing out if the tap I get 10-20.. I guesstimate 15ppm. Not even one dKh.
Anyway adding co2 to any significant degree means that the ph ends up down in the lower 6's ...6.4 will get the drop checker close. I've decided to add baking soda and bring the dkh up to ~5.. after dosing the pH went up to 7.13 (according to my new controller) and the co2 started flowing.
I set the target to 6.7... so hopefully the co2 ppm will end up in the mid 20's...
That's my story of my ongoing progress, so now to my question;

Do those of you using a controller, plug it into the timer (so it quits at night and both the co2 and pH change) or do you leave it plugged in permanently (so the ppm co2 and pH stay the same)?
I know the plants don't need the co2 at night but the pH swing (hopefully less now my water is buffered) may not be beneficial to my shrimp and fish.

Also for those using a bubble counter with the controller, what approximate bubble count do you set so that the controller and water and reactor have proper time to work congruously?

Last edited by blawrence; 09-07-2011 at 12:56 PM. Reason: too many typo's.. fixed em.
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post #2 of 8 (permalink) Old 09-07-2011, 04:36 AM
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The change in pH with a X change in ppm of CO2 in the water is the same with a KH of 1 or 10. All the KH does is raise the pH, not reduce the "swing" in pH with CO2. "Buffering" as used to describe what KH does, where CO2 is concerned, requires a KH of even less than 1, possibly even .1, but I don't know if anyone has actually done the experimenting to determine that. I do know, from a scientific article I read a few years ago, that CO2 can't drive the pH much below 5.5 at typical aquarium water temperatures. That suggests to me that there is a lower limit on KH, but I don't know what it is.

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post #3 of 8 (permalink) Old 09-09-2011, 01:31 AM
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Quote:
Originally Posted by blawrence View Post
I, like another member of the forum, have absurdly low kh .. testing out if the tap I get 10-20.. I guesstimate 15ppm. Not even one dKh.
Anyway adding co2 to any significant degree means that the ph ends up down in the lower 6's ...6.4 will get the drop checker close. I've decided to add baking soda and bring the dkh up to ~5.. after dosing the pH went up to 7.13 (according to my new controller) and the co2 started flowing.
I set the target to 6.7... so hopefully the co2 ppm will end up in the mid 20's...
That's my story of my ongoing progress, so now to my question;

Do those of you using a controller, plug it into the timer (so it quits at night and both the co2 and pH change) or do you leave it plugged in permanently (so the ppm co2 and pH stay the same)?
I know the plants don't need the co2 at night but the pH swing (hopefully less now my water is buffered) may not be beneficial to my shrimp and fish.

Also for those using a bubble counter with the controller, what approximate bubble count do you set so that the controller and water and reactor have proper time to work congruously?
I have a CO2 controller and have been using it for three years. I leave it on 24/7. I adjust the kH to 4 deg and the pH to 6.8. This results in a CO2 concentration of about 20 ppm.

I set my bubble counter for about 1 bpm and in my 52 gal well planted tank, the controller is off half the time.

If you play with chemicals you should know some chemisty.
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post #4 of 8 (permalink) Old 09-09-2011, 08:20 PM Thread Starter
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Quote:
Originally Posted by ray-the-pilot View Post
I have a CO2 controller and have been using it for three years. I leave it on 24/7. I adjust the kH to 4 deg and the pH to 6.8. This results in a CO2 concentration of about 20 ppm.

I set my bubble counter for about 1 bpm and in my 52 gal well planted tank, the controller is off half the time.
1 bpm... tricky

I so do you keep your controller plugged into your timer? I figured I could leave it on 24/7 as well (plugged into the power strip) and the plant usage would go to 0 and the only CO2 loss would be through the surface.. It would keep more consistent parameters for the livestock, but it would save CO2 to let it turn off at night and accept the pH swing.

from what I understand the pH caused by CO2 is not a problem for fish. the pH caused by the TDS (carbonates.. etc) are what can be an issue. .. but that said.. acidic is acidic.. why is a low pH caused by CO2 not an 'issue'? .. (this is going by what I've read in previous threads)
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post #5 of 8 (permalink) Old 09-09-2011, 10:10 PM
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The better question is "why is low pH an issue?" We know from experience that low pH caused by CO2 isn't an issue. How do we know that low pH in general is an issue?

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post #6 of 8 (permalink) Old 09-10-2011, 04:17 AM Thread Starter
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Well again.. from what I've read, only some creatures have a problem with it. Cardinal tetras supposedly like lower ph and soft water... so they're good .. but I've read that shrimp may not like it (lower ph) and some fish species may not like it either... but it has to get pretty low to actually cause issue. I guess I'll just let the hardness go back down and not try to buffer it. I'll probably keep the controller plugged in 24/7 and pay the premium in co2... its cheap anyway.
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post #7 of 8 (permalink) Old 09-11-2011, 07:03 AM
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ok im out on a limb here but from what i have read nitrifying bacteria like a stable ph
ph below 6 is shown to stop nitrifying bacteria growth
beyond that there is no problem running 24/7 i have been doing it for 5 years
i like a stable ph and have found my water clearer when running 24/7
that said its important that the oxygen saturation at night not dip
(at least not much)
the nice thing a about running co2 24/7 is that its barely on at night
and in the morning , well its the same saturation level so its not like it has to increase from 5 to 30 ppm its already there. in other words you co2 usage go goes up very little
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post #8 of 8 (permalink) Old 09-11-2011, 12:55 PM
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Using more CO2 with a CO2 controller is just spin.
While it is true that running your CO2 controller at night will use a little more CO2. ou probably will use less CO2 as you can keep it at a defined controlled level as opposed to having it go to some higher level during the day where it disperses into the atmosphere faster.
While that is my opinion, the fact is that when I use my CO2 controller on a 52 gal tank 24/7, I use about 5# of CO2 in 4 months. This costs about $9.00, which is cheaper than fish food for me.

If you play with chemicals you should know some chemisty.
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