# pH and tannins



## excal88 (Apr 4, 2011)

Hey guys, I had a quick question. Right now I'm leeching tannins into my 26 gallon tank to help lower my tap water pH. On the first day it was at 7.4, but now its back up to 7.8. How long does it take for the tannins to lower the pH? Thanks!


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## redchigh (Jan 20, 2010)

Tannins will only lower ph if the buffering capacity is low.. If your Kh is high, it might take quite a while.


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## Byron (Mar 7, 2009)

And maybe never:shock:. You can find out the hardness of your water from the supply people, many now have a website with water data posted. Find the GH (general hardness) and KH (carbonate hardness) if you can. When we know those numbers, we can offer suggestions.

Also, as your pH is rising, we might as well look at something else...is there any calcareous substance in the aquarium? Gravel, sand, rock made of calcareous rock (limestone, marble, dolomite) or coral (shells, coral sand...)?


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## excal88 (Apr 4, 2011)

Well, my water is really hard, with a 12 degree hardness and pretty high kH, can't recall it exactly but I know it's pretty hard. And my tap is at 7.8, so I found it interesting that it would lower and then go back to ita starting pH. The only thing I have is play sand, no rocks or any shells of the sort
_Posted via Mobile Device_

Just wondering cause I didn't want to mix ro water with my tap to lower it, but If I have to I'll do it.


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## Byron (Mar 7, 2009)

OK then, assuming you have very hard water with a high KH, it will buffer the pH to prevent it from lowering. The buffering capacity depends upon the degree of hardness, and the effect of tannins from a bit of wood is unlikely to have any effect until the point at which we exhaust the buffering capacity.

Neither would many pH adjustment preparations, and the danger in using any of those is the fluctuating pH (going down then back up again). If the buffering capacity is finally reached, the result could be a sudden and significant drop in pH, which can kill many fish outright. I'm not implying your intention to try these, just pointing out their dangers.

The safest method is to soften the water, and this can be done in a few ways. But we would need to know the hardness numbers in order to assess the best.

Byron.


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## excal88 (Apr 4, 2011)

Yea, here's the pdf file on my local water info. Its a bit old, based off of 2010, but its still better than nothing. 

http://www.irwd.com/assets/files/brochures/IRWD%202010%20WQR.pdf

Apparently my tap has 45 ppm worth of nitrate. Crazy. kH is 10, gH is 12. Sorry for not being able to post up more specific details, not that good at reading the data.


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## Byron (Mar 7, 2009)

excal88 said:


> Yea, here's the pdf file on my local water info. Its a bit old, based off of 2010, but its still better than nothing.
> 
> http://www.irwd.com/assets/files/brochures/IRWD 2010 WQR.pdf
> 
> Apparently my tap has 45 ppm worth of nitrate. Crazy. kH is 10, gH is 12. Sorry for not being able to post up more specific details, not that good at reading the data.


There is a lot of variability in that report, but I think we can accept that you have medium hard (or harder) water. So there is going to be stable buffering. Was there a reason you wanted to lower the pH?


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## excal88 (Apr 4, 2011)

Oh, I plan to have cory cats in the tank, and I read up that they prefer softer/ more acidic water. Realistically I want a more neutral pH, say 7.2-7.4 as it would be nice for my cory cats to spawn *if I have male/female pairs * but other than making it a bit more comfortable for my fish, theres not a big reason for lowering the pH.


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## Byron (Mar 7, 2009)

excal88 said:


> Oh, I plan to have cory cats in the tank, and I read up that they prefer softer/ more acidic water. Realistically I want a more neutral pH, say 7.2-7.4 as it would be nice for my cory cats to spawn *if I have male/female pairs * but other than making it a bit more comfortable for my fish, theres not a big reason for lowering the pH.


If you're working with tank-raised species, you will (should) not have a problem with long-term care and it should be possible to spawn them, other things being provided. But if you are dealing with wild-caught species, spawning would be very unlikely without very soft water.

It is actually the hardness more than the pH, though the pH tends to be relative to the hardness so it naturally falls if the hardness falls. Hard water affects soft water fish in various ways, and many will not spawn or if they do the eggs cannot be fertilized or do not develop properly due to the effects of the minerals in the water.

Having said that, if you want you can soften the water by diluting the tap water with RO (reverse osmosis) water, distilled water or rainwater (if it is clean, meaning no toxins). Depending upon the tank size, this can be a viable option. Once the initial water is soft or softer, the pH will naturally fall a bit, and the biological workings will keep it fairly stable. Water changes can be smaller and should not affect this too much.

Byron.


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## excal88 (Apr 4, 2011)

Byron said:


> If you're working with tank-raised species, you will (should) not have a problem with long-term care and it should be possible to spawn them, other things being provided. But if you are dealing with wild-caught species, spawning would be very unlikely without very soft water.
> 
> It is actually the hardness more than the pH, though the pH tends to be relative to the hardness so it naturally falls if the hardness falls. Hard water affects soft water fish in various ways, and many will not spawn or if they do the eggs cannot be fertilized or do not develop properly due to the effects of the minerals in the water.
> 
> ...


Ah, I see. I am not sure if the ones I got were wild-caught or captive bred, but the water should soften naturally, correct? It'll just take some time. I'm all for natural occurring things, so I want to avoid additives if possible. For now I guess I'll let the tank sit and simmer on its own. Thanks for the tips Byron.


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## Byron (Mar 7, 2009)

excal88 said:


> Ah, I see. I am not sure if the ones I got were wild-caught or captive bred, but the water should soften naturally, correct? It'll just take some time. I'm all for natural occurring things, so I want to avoid additives if possible. For now I guess I'll let the tank sit and simmer on its own. Thanks for the tips Byron.


What is/are the cory species? I can tell from this.

No, the water in an aquarium will slightly soften over time, but this is minimal. Once it is diluted and made softer, it will stay that way.


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## excal88 (Apr 4, 2011)

Currently have 3 panda corys, 3 false julii corys, and 4 sterbai corys. I'll use the water mix when I do water changes for a week or so then to help soften the water.


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## Byron (Mar 7, 2009)

excal88 said:


> Currently have 3 panda corys, 3 false julii corys, and 4 sterbai corys. I'll use the water mix when I do water changes for a week or so then to help soften the water.


That should work, a slow change with several smallish water changes over several days.

Corydoras panda and C. sterbai are being tank raised so if purchased in a store will most likely not be wild caught unless it is a speciality fish store that does direct importing. C. trilineatus [the usual non-julii species] I'm not sure about, but I believe these are being commercially raised. However, C. panda is a sensitive cory, and all 3 of these would be more likely to spawn in soft water. You have different temperature requirements though, so check our profiles on that.

I can give you some links to spawning tips if asked.

Byron.


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## excal88 (Apr 4, 2011)

So interesting thing, my pH has gone up to 8.0 from 7.8 without me adding anything save water *which the pH was at 7.8* and the pH stayed steady at 7.8 for the past couple days. The I also did add a light fixture and started using it, but it shouldn't cause a rise in pH, would it? Guess its back to the RO water machine for me. Haha.


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