# CO2 and pH



## finfollower (May 27, 2004)

hey guys,
can anyone explain the basics of the relation between CO2 and the pH? Ever since I added plants into the tank, I've been overdosing excel by twice as much as the recommended dosage. When I first started my tank, the water pH was at about 7 and everytime I dose excel, the pH goes down to about 6.4 or lower. How can I fix this?


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## hoppycalif (Apr 7, 2005)

There is nothing there to fix. If you were dosing CO2 the pH would drop. Dosing Excel may have the same effect, but Excel does not add CO2 to the water - it adds a compound of carbon that plants can use instead of or in addition to CO2. The fish won't be harmed by that drop in pH.


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## finfollower (May 27, 2004)

After dosing the excel, will the pH return back to what it was before? Also, how would the drop in pH not affect the fish? I know that most fish tolerate pH from 6-8, but a drop in .6-.8 in a short period of time would surely stress the fish wouldn't it?


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## John N. (Dec 11, 2005)

Never heard of Excel dropping pH but I guess it's possible. I never really checked. The pH drop could be from intitially putting tap water in your tank and you're measuring the degased level vs straight from the tap.

But in anycase, a drop of pH would be stressful to fish, but fish can handle a lot of things. They usually get hit by a sudden pH change in real life..such as a rain storm..

If the excel is causing your pH to drop, then regular dosing should keep it level...since the pH would rise after the plants consume the dose of excel for that day...

Interesting, I wonder what's causing your pH to drop.

-John N.


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## hoppycalif (Apr 7, 2005)

I am interpreting your statement: "everytime I dose Excel the pH goes down to 6.4" as meaning it goes back to 7.0 between doses. If so, it certainly appears that Excel drops the pH like CO2 does. It would be an interesting test to do - add Excel to a bowl of water, after the water sits out for a day or two to outgas, and see what that does to the pH. This is a holiday weekend, so I feel obligated to be lazy, so who wants to do the test???


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## finfollower (May 27, 2004)

Could my driftwood be causing the pH to drop? I'm just wondering, but I highly doubt it as it's been treated already. I also have a rock from my backyard in there. By the way, my tap water is really high. It's greater than 8 but I'm not totally sure what the exact pH is. I usually just add a few drops of pH down to the bucket of water I use to refill my tanks and I just did my first water change on my new tank about an hour ago and the pH hasn't dropped yet after a 2x dose of excel and a dose of flourish


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## Bert H (Mar 2, 2004)

Do the following test: take a sample of your tap and let it sit out for 24 hours. Measure the pH. That's a more accurate measure of pH than out of the tap because it has had a chance to degas from your pipes, etc. Don't add chemicals to change your pH. Your fish won't be hurt by the pH switches you describe. As has been mentioned, everytime a rainstorm comes along, local pH changes from stuff leaching out into the water/river/lake. I have not heard Excel causing pH changes, you might post a similar question in the Seachem forum for their folks to address. If I was a betting man, I'd wager that you're getting the variability you're getting due to degassing more than anything else. Keep us posted. 

BTW, what's your kh? If your tap pH is indeed 8, I would expect your kh to be around 9-10. You can test your rock easily enough by adding some hydrochloric acid to it and see if it fizzes/bubbles. If it does, it's calcium carbonate and probably should not be used in your tank.


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## finfollower (May 27, 2004)

uhh what kind of ordinary household products would contain hydrochloric acid?


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## hoppycalif (Apr 7, 2005)

The easiest to find hydrochloric acid is swimming pool acid - the liquid type. Just remember that it is dangerous stuff, don't breathe the fumes, don't pour water into acid-pour acid into water, it damages your eyes if the fumes get too strong in your eyes, etc. But, with care you can use it for testing rocks. Storing the remainder can be a drag, and disposing of it legally is a problem. Maybe worth it to put in a swimming pool just to have a place to get rid of it?


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## finfollower (May 27, 2004)

gahh is there an easier way to do this as i don't have a pool...i heard something about using vinegar to test for limestone. are limestone and calcium carbonate the same?


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## Ownager2004 (Apr 18, 2006)

I thought I remembered hearing somewhere that excel contained carbon in the form of the bicarbonate ion. The bicarbonate ion is a ph buffer (plays an important role in our blood) so im not surprised that it affects the ph. As for the chemistry of it and why it does Im feeling to lazy to look it up... Ill leave that to someone else


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## hoppycalif (Apr 7, 2005)

finfollower said:


> gahh is there an easier way to do this as i don't have a pool...i heard something about using vinegar to test for limestone. are limestone and calcium carbonate the same?


Yes, they are the same, just different crystal form as I recall. Vinegar might work, but you would have to watch more carefully for bubbling since vinegar isn't a strong acid.


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## finfollower (May 27, 2004)

ah, cause I tested my rock with vinegar and I didn't see/hear any bubbling or fizzing. Also, I left out some untreated tap water last night and checked its pH this morning. The pH dropped from 8ish down to about 7.2/7.4. As for my tank, a few hours after the water change I did yesterday, the pH was at about 6.8 and I checked again today and it was at about 6.4-6.2ish


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## finfollower (May 27, 2004)

After doing some research, I think that my driftwood is the cause of the pH drop and in addition to that, perhaps the CO2 could lower it also, but not by much. If my rock were limestone, my pH would be getting higher and this isn't the case. So I guess the guy at Petco kinda lied to me about the driftwood being treated and ready to stick in the tank. How long would the water be affected by driftwood and how can I raise my pH. Cause right now, the pH is too low for my chart to measure and I would like to add fish ASAP.


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## erijnal (Apr 5, 2006)

Quick note, driftwood should ALWAYS be at least rinsed thoroughly before being put into your tank. Most people boil their driftwood just to be sure there's nothing strange that gets into their tanks. A side-effect of boiling though seems to be a loss of leaching from the driftwood. I personally like my driftwood to leach tannic/muriatic acids because I keep cardinal tetras, but some people put their driftwood in a bucket of water for a month or two to get rid of the tannins. 

I believe you can raise your pH by running an airstone throughout the day, but I might be wrong on this, so someone please correct me if i am. 

As for your pH dropping with the addition of Excel, I am completely puzzled by that. I thought the general consensus was that Excel did nothing to the pH. Could you tell us what testing kit you're using to measure your pH? If you're using the 5-in-1 test strips, that might be the reason for your strange readings. If you are using test strips, i suggest you go back to petco and buy a cheap aquarium pharmacueticals pH testing kit, it should give you much more reliable results.

As for adding fish to the new aquarium, if your tank is well-planted, you should be fine as long as you acclimate your fish properly (i recommend the drip method). Most fish do fine in pH's of 6.5-7.5 i believe. If the tank is not well-planted, then I would add a hardy fish like the White Cloud Minnow to the tank to get the sucker cycled so you don't have to worry about nitrite/ammonia. Once the tank is cycled you can try going to an LFS and ask them if they'll take it off your hands, or keep them.

Anyway, I hope this was helpful


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## finfollower (May 27, 2004)

erijnal,
I'm using aquapharm.'s dluxe pH testing kit and it's working alright except it's been showing me really low pH levels for my planted tank. The excel changing the pH thing was just a guess I made when I started this thread, and it's been disproven. As for the driftwood, I was informed that the wood was already treated and all I need to do was rinse it in some running water. When I added it into my tank I didn't see any change in water coloration. I'm going to the LFS today and I'll get my water tested there as well to match up with my results.


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