PH + CO2

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Feynman

Aquarium Advice Activist
Joined
Oct 11, 2004
Messages
106
Location
Dallas, Texas
Last night I turned on my pressurized CO2 system for the first time and within an hour I had almost killed my Kribs. It turned out that I had a drastic drop in PH. From 7.2 to less then 6.0 (I don't have a test that goes below 6.0 but after 50% water change and the rest of my PH stabilizer stuff I only got it up to about 6.6).

So what's the deal? I can't imagine I had put in sooo much CO2 in under an hour that it overwhelmed my tank and caused the PH crash when people here leave their CO2 on 24/7.

I clearly need some buffer to control the PH. So I tested my KH to see where I'm starting. KH read at 7 DH. Does that explain what happened to me? What do I add to keep PH level? Baking Soda? Not sure I want to put crushed coral in my freshwater tank, but... would it work in my canister filter? Am I even going in the right direction?
 
It would help to know the system you are working with, as well as how fast (bubble/second) you were injecting for that hour.
 
Your numbers suggest a CO2 level of about 210ppm. I don't see enough detail to say anything other than yes it is possible.
PH stabilizer usually equals KH buffer, so be carefull of how much you use. In fact depending on brand it may just be baking soda in water. (expensive baking soda in water)
 
Unfortunately no, I don't have a PH controller.

This is my 38 gallon (which I like to call 40) tank. I can't say for sure the number of bubbles per second. Maybe 7 - 12 bubs/sec. I wasn't sure what to go for so I just guessed.

Is the 7 deg KH low then?
 
so... I'm going to slow my CO2 rate and increase my KH buffer.

What is your preferred method of increasing KH?
 
(I've not run pressurized.)

I think reducing CO2 rate will be enough. Start with low bps (say, 1-2) and go up if you need to, as 38gal isn't a lot of water. 7 dkH is fine. Your aged tap's pH is 7.2?
 
Feynman said:
Unfortunately no, I don't have a PH controller.

This is my 38 gallon (which I like to call 40) tank. I can't say for sure the number of bubbles per second. Maybe 7 - 12 bubs/sec. I wasn't sure what to go for so I just guessed.

Is the 7 deg KH low then?

Ok, 7dKh is not low...and in fact your pH looks too low for a dKh of 7 (prior to CO2 injection). It should be more like 7.6 normally.

7-12bps is entirely too many. start at .5 bubbles per second (30/minute) and adjust from there. You were drastically over injecting CO2...which is why you drove the pH so low and CO2 levels so high.

But I would investigate why your pH is abnormally low to start with...you don't use anything like pH Down do you?

The issue is, with an 'off pH' like yours, something else is affectign the water's buffering, adn so the whole pH/Kh chart for determining CO2 levels can''t be used. If we use it on your non-injected water (7.2 & 7dKh) that puts you at almost 15ppm of CO2 without injection...which isn't possible unless you have about 200 fish in that tank and zero surface agitation.
 
I turned down the CO2 and everything is fine. Guess I just got a little too excited. Thanks for the replies.
 
Please read
http://www.aquariumadvice.com/showquestion.php?faq=2&fldAuto=41

It is a very good article on CO2. And should help you figure out how much CO2 you have / and or need.

If you are worried about your PH that much, there is gravel and sands that will buffer your ph a lot better then any chemical including baking soda. Onyx Sand and gravel is one.

Most fish with a few exceptions can handle PH 6.5 - 8. Some more hearty fish can go even further. Look up info on your fish first.

I would do bi-daily or daily 20% water changes to get all the dumb PH stabilizer out of your water as it has little to no useful / good effect after a short amount of time and ends up just being more odd chemicals your fish don't like. Trust me, I made that mistake.
 
Hey! Well, I'm making a Log in an access database (I'm in systems analyst) to track ALL changes and levels in my tank, so i can see things as they start to go awry, and have a baseline to work on, as well as see how every new plant/fish/food/decoration effects my tank.
I'm looking for an automated way to calculate the CO2 levels from the PH and Carbonate hardness. Does anyone know the forumla in the form of x + y = z? Or do you have to balance a bunch of chemical equations that i'd need some advanced programming for? :p I'm thinking of looking at the source code of a website online.... but i dont know if that'd be legal or not. I'll contact the system admin if it comes down to that.
 
sweet deal! i'll try it out tonight!

Anyone have access that will want my completed database?
Its not going to be too user friendly yet, and you must have microsoft access for it to work.
 
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