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whitecloud34 04-16-2011 07:57 PM

Please tell me if my theory on pH is correct?
 
-So acidic water automatically converts ammonia into ammonium;
-and 6.0 pH is too acidic for the nitrogen cycle to happen (right?)

^Given that, is it essentially true, then, that as long as you keep your pH at a stable 6.0 then you don't even need the tank to cycle? And then you don't even need plants to do the naturally planted aquarium because the ammonium is harmless anyway? I'm still learning and trying to work this out in my head...

I've been cycling my tank for about 6 weeks now and slowly my pH kept dropping to more acidic. It started gradually. When I first set the tank up it was really alkaline because of the tap water and it was a struggle to get it up to my desired 6.8. A few weeks later and it was easy to keep it at 6.8. Then it started going to 6.4 and then it was a stable 6.0 and has remained so. Well just days before it went to 6.0 I got a nitrite reading! But then a couple days later the pH was 6.0, and like a horrible trick, the nitrites disappeared, still no nitrates. Then I learned that nitrites die off in water that is this acidic. So. I've been struggling with pH Up to get it back to 6.8 but the next day it's right back at 6.0. So I figured, okay forget this cycle, it wasn't meant for me. I was considering doing the planted tank so that the plants eat up the ammonia/ammonium and I never have to even deal with nitrites/nitrates. But, going back to my initial question, are the plants even needed in a pH of 6.0? (I ask this because I've had HORRIBLE luck with plants years ago. Still want to get some but they most likely will die...) Because at 6.0 the ammonia is ammonium and there will never be nitrites/nitrates because it's too acidic for them to thrive... I figure as long as I do 20% water changes/gravel vac say twice a week, and make sure the pH stays at 6.0, my fish will be fine. Right? Am I right here or is there something I am missing? Like I said, I'm still new to this whole thing...Thanks!

Mikaila31 04-17-2011 03:07 AM

No because ammonium is NOT non-toxic, its just less toxic then ammonia. It can still cause harm especially if you let it get high enough. Also its still a very reactive form of nitrogen. Your tank will be algae central in no time if you constantly have ammonium built up....

whitecloud34 04-17-2011 10:58 AM

Quote:

Originally Posted by Mikaila31 (Post 650549)
No because ammonium is NOT non-toxic, its just less toxic then ammonia. It can still cause harm especially if you let it get high enough. Also its still a very reactive form of nitrogen. Your tank will be algae central in no time if you constantly have ammonium built up....

Ah I knew it was too good to be true :-? lol This tank is so hard to handle. I don't know what to do anymore.

DKRST 04-17-2011 11:33 AM

Quote:

Originally Posted by whitecloud34 (Post 650212)
-So acidic water automatically converts ammonia into ammonium;
-and 6.0 pH is too acidic for the nitrogen cycle to happen (right?)
Because at 6.0 the ammonia is ammonium and there will never be nitrites/nitrates because it's too acidic for them to thrive...

Six point zero is on the low side for pH but even at that pH, over time, you'll get a bacterial bed established, in my opinion. A few questions. How are you testing pH, and what is the pH of your tapwater before you put it in the tank? Also, what do you use in the tank for substrate and decorations? Any driftwood?

If your tapwater comes out near a pH7, which it should if it's municipal supplied, then the cause of the shift must be in your tank. More details should help us narrow it down.

Byron 04-17-2011 12:00 PM

1 Attachment(s)
I suspect your initial questions come from something I posted elsewhere. Mikaila is correct, so what follows is not intended as any sort of counter, just so you understand.

I am not a biochemist or microbiologist, so my views are the result of research into a very complicated area. Sometimes in attempting to help others I oversimplify, as much because I don't fully comprehend the complexities (or can't adequately explain them if I do understand them) as well as not wanting to bog things down to the point where someone "gives up." While it is good to know what occurs, sometimes it is best to let it do so without intervening. And of course, science continues to make advances in our understanding of the world around us. What is honestly believed to be the case today can be seen to be the opposite tomorrow.

Here is an excerpt from an article on nitrifying bacteria that you can read in full at
Autotrophic Nitrifying Bacteria and Their Practical Application in a Freshwater Tank
Autotrophic Nitrifying Bacteria and pH

pH has a significant effect on autotrophic nitrifying bacteria. At a pH below 6.5, they become inhibited and cease being efficient in oxidizing ammonia and nitrite. Maximum rates of nitrification occur at pH values above 7.2, with optimal nitrification occurring around 8.3. At a pH of 8.3, nitrifying bacteria operate at near 100% effectiveness. At a pH of 7.0, their efficiency drops to less than 50%. At a pH of 6.5, it drops to 30%, and at a pH of 6.0, it drops to 10% optimal efficiency.

[see chart below]

At pH values below 6.0, autotrophic nitrifying bacteria donít die, they just stop functioning and reproducing. We are fortunate that at these low pH values, most ammonia (NH3) is ionized into its non-toxic form, ammonium (NH4).
The above is concerned solely with the usual nitrifying bacteria in aquaria. But there are other bacteria that perform similar functions, or at any rate the end result is similar, using biofilm. I read one such study, but it is frankly well beyond my comprehension. I am satisfied to know that the fish in my aquarium will not have issues in very soft water with a low pH, whatever may be the method.

With live plants, and all else being equal, you will not have issues with ammonia, nitrite or nitrate at a pH of 5 or 6. I have tanks with a pH of 5, the fish are healthy, and nitrates register 0-5 ppm. I'm not going to worry.

Byron 04-17-2011 12:09 PM

My prior post was aimed at the pH/bacteria issue. In this present response, I'll comment on your particular situation as you have set it out.

The water in an aquarium with fish will tend to acidify due to the biology. This is reflected in the pH which will lower as it acidifies. The rate and extent to which this occurs is largely based upon the hardness, particularly carbonate but also general. Other factors also affect this, such as wood, leaves, organics also causing acids, or the opposite in calcareous rock or substrate causing an opposite effect. And water changes impact too; the more water changed using water with a higher hardness or pH than the tank water will work to maintain a higher pH. DKRST is referring to this in his post.

As your tank seems to be performing very similar to mine, I would expect your tap water to be fairly soft. Can you give us the hardness (you can get this from your water supply folks) and pH?

Byron.

whitecloud34 04-17-2011 12:25 PM

Quote:

Originally Posted by DKRST (Post 650772)
Six point zero is on the low side for pH but even at that pH, over time, you'll get a bacterial bed established, in my opinion. A few questions. How are you testing pH, and what is the pH of your tapwater before you put it in the tank? Also, what do you use in the tank for substrate and decorations? Any driftwood?

If your tapwater comes out near a pH7, which it should if it's municipal supplied, then the cause of the shift must be in your tank. More details should help us narrow it down.

I test with the API kit and the pH of the tap water is 7.4 or 7.6 the last I tested it. I use just regular black coated gravel from the petstore. The only decorations I have in there are plastic plants and a little castle. No driftwood. Before this low pH thing I would put pH down in the bucket before adding it to the tank so it was 6.8 but now I just throw the water in there (treated with Prime of course) at 7.4 and it bringts the pH up to 6.4 when it's a 20% water change but it goes back to 6.0 eventually. I actually was wondering if the Prime was doing it but I tested the pH of it and it was like 7.8 so I ruled that out.

whitecloud34 04-17-2011 12:31 PM

Quote:

Originally Posted by Byron (Post 650815)
My prior post was aimed at the pH/bacteria issue. In this present response, I'll comment on your particular situation as you have set it out.

The water in an aquarium with fish will tend to acidify due to the biology. This is reflected in the pH which will lower as it acidifies. The rate and extent to which this occurs is largely based upon the hardness, particularly carbonate but also general. Other factors also affect this, such as wood, leaves, organics also causing acids, or the opposite in calcareous rock or substrate causing an opposite effect. And water changes impact too; the more water changed using water with a higher hardness or pH than the tank water will work to maintain a higher pH. DKRST is referring to this in his post.

As your tank seems to be performing very similar to mine, I would expect your tap water to be fairly soft. Can you give us the hardness (you can get this from your water supply folks) and pH?

Byron.

Thank you very much. That I will work on. I'm hoping to bring a water sample to Petco. and see if they can test it. If not I may have to contact the water supply for the city. But I don't think we have hard water because whenever I took vacations to Florida, I noticed the soap would not lather and I was told this was because they have hard water. At home the soap lathers so I'm guessing we don't have hardwater. I don't know if that's a way to tell lol but that's how I've always figured it in the past.

Byron 04-17-2011 01:00 PM

Quote:

Originally Posted by whitecloud34 (Post 650833)
Thank you very much. That I will work on. I'm hoping to bring a water sample to Petco. and see if they can test it. If not I may have to contact the water supply for the city. But I don't think we have hard water because whenever I took vacations to Florida, I noticed the soap would not lather and I was told this was because they have hard water. At home the soap lathers so I'm guessing we don't have hardwater. I don't know if that's a way to tell lol but that's how I've always figured it in the past.

I would contact the water supply and not rely on tests at a pet store which can be misleading. The water people can tell you what you have and it will be accurate and reliable.

Yes, I'm still suspecting soft-ish water, but let's see the data.

On the issue of pH adjusting chemicals, don't use these. They can often cause significant pH shifts too quickly. Now I am understanding why you are having such fluctuations. This is highly stressful on any fish. We work best with nature, let the water do what it will without intervention. Those hardness numbers will tell us more.

whitecloud34 04-17-2011 01:20 PM

Quote:

Originally Posted by Byron (Post 650857)
I would contact the water supply and not rely on tests at a pet store which can be misleading. The water people can tell you what you have and it will be accurate and reliable.

Yes, I'm still suspecting soft-ish water, but let's see the data.

On the issue of pH adjusting chemicals, don't use these. They can often cause significant pH shifts too quickly. Now I am understanding why you are having such fluctuations. This is highly stressful on any fish. We work best with nature, let the water do what it will without intervention. Those hardness numbers will tell us more.

Ok that's what I'll do then. I'll contact them and I'll post the results on here when I do that this week. Thanks again.


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