[rpadgett37]

I understand the nitrogen cycle pretty well, but I've run into something that has me stumped.

First the question: Is there a direct relationship between KH and the growth of Nitrifying Bacteria?

Here's why I ask: I am cycling a tank at the moment with ammonia. I have followed the online instructions I found on the Betta site and have a starting point of 5ppm ammonia concentration in the water.

The starting water parameters are PH 7.9, KH 1dK and temp 78-80 degrees.

I have seeded the tank with Bacteria, a couple of different products actually (Seachem Stability for 7 days, then Nutrafin Safe Start Plus on day 8). After 9 days, I am seeing no movement whatsoever either in ammonia or nitrite levels. I've used tests by API and Nutrafin each time I measure to be sure I am getting accurate measurements. The tank I cycled previously showed nitrites on day 3 after seeding the tank, and I am stumped as to why nothing is happening in this tank.

Someone suggested to me that low kH levels will inhibit nitrifying bacteria growth and function. I know that as PH values lessen, nitrifying bacteria growth and function slow and eventually stop altogether at around PH 6, and that there is a direct relationship between PH and KH. As my starting kH is so low, this comment piqued my interest.

The only problem is I can find nothing on the internet that corroborates a relationship between kh and these bacteria. Only about PH. Now I know that nitrifying bacteria use (among other things) carbon in the water to do their thing, so does that mean if the carbon source in the water is either very limited or non existent, they stop working or fail to grow at all?

There you have it. Your comments and experience are welcome.

 

[sprmankalel]

I don't know anything about your question here but I had a few myself.
Do you have an already established tank? If so, I would suggest taking some media from there and put it into the new tank's filter and see what happens to the ammonia levels. Having one or more established tanks means infant cycling of new tanks.

 

[rpadgett37]

I don't know anything about your question here but I had a few myself.
Do you have an already established tank? If so, I would suggest taking some media from there and put it into the new tank's filter and see what happens to the ammonia levels. Having one or more established tanks means infant cycling of new tanks.

Unfortunately, this is the first tank of 5. This will be the tank that seeds the others.

 

[sprmankalel]

Anyone that you can get media from?

 

[rpadgett37]

Anyone that you can get media from?

Yes, but not anytime soon.

 

[sprmankalel]

I'd say let it be for a few days. As long as you have an ammonia source in the tank it should happen.
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[RSVBiffer]

Nitrifying bacteria are affected by pH rather than alkalinity. For a cycling tank though (or even a mature tank) your KH is too low as it will allow pH swings and cycling tends to drop the pH and you have nothing to buffer against it. I would suggest you raise it to somewhere around 4dKH (at the minimum). Your pH is fine at the moment but once the cycle kicks in you are going to be very prone to crashes.

 

[rsskylight04]

For buffer I would reccomend natural sources such as limestone, coral, or seashells rather than chemical sources like baking soda. Natural sources provide slow release longterm buffer while baking soda is fast acting and must be carefully measured and re dosed with each water change. Crushed coral is available at most pet shops and a can be put directly into the tank or in a mesh bag in your filter.

 

[rpadgett37]

Already have something standing by to fix the kH.

PH rather than Alkalinity? Not sure what you mean by that. Alkalinity is a part of PH, so what am I missing here?

Also still interested in why my cycle isn't going anywhere though it has good parameters.

 

[beaslbob]

I remember reading an old article that the forward aerobic bacteria cycle does in fact use up KH. Whether or not low KH affects the bacteria is another question.
And further that the reduction of the resuting nitrates through either plant or bacterial activity in fact returns that KH.

But that was an article from years ago.

 

[rpadgett37]

I remember reading an old article that the forward aerobic bacteria cycle does in fact use up KH. Whether or not low KH affects the bacteria is another question.
And further that the reduction of the resuting nitrates through either plant or bacterial activity in fact returns that KH.

But that was an article from years ago.

Interesting. There aren't any plants in there at the moment, so it sounds like to be sure, I will need to raise the Kh and see what happens.

 

[beaslbob]

Interesting. There aren't any plants in there at the moment, so it sounds like to be sure, I will need to raise the Kh and see what happens.

The kH is also increased throu anoxic bacteria reducing nitrates in the substrate.

FWIW I have had pH values of over 8.4 in my planted tanks even with peat moss in the substrate.

And with the peat moss the kH is 4 degrees for at least 2 years. KH did rise on the tank I had just plain sand though.

Tanks were not circulated and the plant action IMHO made the tank a net consumer of carbon dioxide and producer of oxygen each 24 hours.

Just shooting in the dark here, if your kH is below 4 degrees I would just add some baking soda to get it up to 4 degrees.

And with a cycling tank the low pH and kH could just be part of the cycle. Once the cycle matures both will probably go up.

If you can, I would add plants even if you had to protect the plants with come kind of partition.

The plant action will consume ammonia directly preventing spikes until the bacteria builds up.

What I would recommend against is adding various things to correct pH problems or help the cycle with chemicals. Dechlors and ammonia locks can stall the cycle and degrade the environment. While adjusting the kH as above it safe, chasing pH is unwise and dangerous. IMHO.


my .02

 

[rpadgett37]

The kH is also increased throu anoxic bacteria reducing nitrates in the substrate.

FWIW I have had pH values of over 8.4 in my planted tanks even with peat moss in the substrate.

And with the peat moss the kH is 4 degrees for at least 2 years. KH did rise on the tank I had just plain sand though.

Tanks were not circulated and the plant action IMHO made the tank a net consumer of carbon dioxide and producer of oxygen each 24 hours.

Just shooting in the dark here, if your kH is below 4 degrees I would just add some baking soda to get it up to 4 degrees.

And with a cycling tank the low pH and kH could just be part of the cycle. Once the cycle matures both will probably go up.

If you can, I would add plants even if you had to protect the plants with come kind of partition.

The plant action will consume ammonia directly preventing spikes until the bacteria builds up.

What I would recommend against is adding various things to correct pH problems or help the cycle with chemicals. Dechlors and ammonia locks can stall the cycle and degrade the environment. While adjusting the kH as above it safe, chasing pH is unwise and dangerous. IMHO.


my .02

The only action I took was to empty the tank, use the same source water to refill it, raised the kh to around 4. I'm letting it sit till tomorrow morning where I'll check water parameters after 18 hours and add ammonia and bacteria once more. This is probably an extreme measure, but I really want to see what happens with keeping everything reasonably the same with a higher KH.

I know better than to chase the PH, and at the moment, the only parameter I am fiddling with is the KH, and that only a little. I wish I could add some plants at this point, but resources are exhausted for the month And it is a bit early for the anoxic bacteria to be doing anything just yet, but it's good to know what effect they will have on the system once in place. There's always so much more to learn.

 

[RSVBiffer]

Already have something standing by to fix the kH.

PH rather than Alkalinity? Not sure what you mean by that. Alkalinity is a part of PH, so what am I missing here?

Also still interested in why my cycle isn't going anywhere though it has good parameters.

Alkalinity is a measure of a systems ability to neutralise acid, i.e. 'soak up' hydrogen ions which would otherwise cause the pH to fall. Pure water has 0dKH, 0dGH but a pH of 7 rather than 1 as there are neither H- or OH-. The higher the alkalinity the higher the buffering capacity which means that to lower the pH we (usually) need to lower the alkalinity. Setups with a low KH but high pH value tend to be unstable and subject to pH crashes. The nett result of the nitrogen cycle is the production of H- ions which would decrease the pH but is counteracted by the buffering effect of the alkalinity.

Regarding your cycle I would say (from your figures) you just need to give it time. It is possible that some factor is affecting it but it also has not been running that long. You give the starting pH etc values but not the current ones, have you checked these lately?

 

[rpadgett37]

Ok. I didn't say that very clearly. The PH is the measurement of the alkalinity, while the alkalinity of the water can impair both growth and function of the nitrifying bacteria. The lower the alkalinty, the more pronounced the effect.

For my clarification, I was under the impression that the alkalinity itself had no buffering capacity, and that it is what needs buffering. I had thought carbonated hardness is what buffers the alkalinity, absorbing H- ions introduced into the water before it can interact with the alkalinity of the water. The higher the Kh measurement of the carbonates in the water, the more buffered alkalinity becomes at a given PH measurement, the less prone it is to fluctuations. Again, for my clarification.

And yes I have. I measure the water daily for PH, KH, ammonia and nitrites. The daily results match the starting measurements.

 

[RSVBiffer]

pH isn't a measurement of the alkalinity. You have a KH of about 20ppm and a pH of 7.9, in my Amazon tank I have a of KH 60-70ppm but a pH of 6.8. There is a direct relationship between the two but other factors come into effect. A specific alkalinity value will give different pH readings in different tanks.

Carbonate hardness is another term for alkalinity.

I think you may be confusing the alkalinity, in terms of an aqueous solution's buffering capacity, with how the pH may be acidic or alkaline and has a' higher alkalinity'. I hope that makes sense. Of course, it shouldn't be alkali but base...at least it would simplify things ;-).

 

[tanked]

Not addressing the kh/cycle relation but possibly your ammonia is too high? Five ppm might be high for any cycle start and my understanding is twoish ppm when using bacteria starters is best? Also eighty degrees F is on the high end for those starters?
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[RSVBiffer]

I would say 5ppm is well within limits, Waterlife advise 5-10ppm before using Bacterlife. The pH is ideal for the Nitrosomonas and slightly high for optimum Nitrobacter growth but certainly nothing to worry about. The temp is ideal for optimum growth of both types of bacteria (77-86'F).

 

[rpadgett37]

pH isn't a measurement of the alkalinity. You have a KH of about 20ppm and a pH of 7.9, in my Amazon tank I have a of KH 60-70ppm but a pH of 6.8. There is a direct relationship between the two but other factors come into effect. A specific alkalinity value will give different pH readings in different tanks.

Carbonate hardness is another term for alkalinity.

I think you may be confusing the alkalinity, in terms of an aqueous solution's buffering capacity, with how the pH may be acidic or alkaline and has a' higher alkalinity'. I hope that makes sense. Of course, it shouldn't be alkali but base...at least it would simplify things ;-).

Yes. I was confusing the two. Again for clarity, PH is a measurement of the total acidic and base compounds in the water? Also, then to say Carbonated Hardness and Alkalinity is saying the same thing, meaning the terms are interchangeable?

If that is the case, then KH does have an impact on the growth and function of nitrifying bacteria (specifically Nitrosomanus). The lower the alkalinity of the water, the more impaired the Nitrosomanus becomes. Is that right? I am guessing that another way to say that is that the more acidic compounds in the water, the more this bacteria is impaired which is why people associate PH with this impairment rather than KH. Really beginning to zero in here.

So if that is correct, then a tank can have the measurements you mentioned (60ppm Carbonated Hardness, PH 6.8) and these bacteria may not be as impaired as say 20ppm and PH 6.8. Hope that's clear.

Already started the restart and the starting value are PH 7.4 (came down from adding sodium bi-carbonate to the water), KH 3dk. Temp same. Ammonia concentration same.

 

[beaslbob]

Yes. I was confusing the two. Again for clarity, PH is a measurement of the total acidic and base compounds in the water? Also, then to say Carbonated Hardness and Alkalinity is saying the same thing, meaning the terms are interchangeable?

If that is the case, then KH does have an impact on the growth and function of nitrifying bacteria (specifically Nitrosomanus). The lower the alkalinity of the water, the more impaired the Nitrosomanus becomes. Is that right? I am guessing that another way to say that is that the more acidic compounds in the water, the more this bacteria is impaired which is why people associate PH with this impairment rather than KH. Really beginning to zero in here.

So if that is correct, then a tank can have the measurements you mentioned (60ppm Carbonated Hardness, PH 6.8) and these bacteria may not be as impaired as say 20ppm and PH 6.8. Hope that's clear.

Already started the restart and the starting value are PH 7.4 (came down from adding sodium bi-carbonate to the water), KH 3dk. Temp same. Ammonia concentration same.

from what i understand carbonate hardness is the carbonate in the system. alk is the resistance to ph changes. So technically they are not precisely the same. But practically, allmost all the resistance to ph change does in fact come from the carbonate ion. So alk is used as a substitute for carbonate because it is much easier to measure.

pH is a function of carbonate, and carbon dioxide (plus the obvious h+ ions and the like).

What I do with my systems is heavily plant them right from the start. This reduces carbon dioxide and consumes ammonia directly. Which prevents the forward aerobic bacteria spikes. Which in turn reduces the h+ ions released which consume alk also.

Plus the reduced carbon dioxide increases the pH.

So after a few weeks the bacteria consume more and more ammonia then nitrItes resulting in nitrates. Which does reduce carbonate but at a much slower rate.

At that point the plants start consuming nitrates which returns the carbonate used up by the aerobic bacteria cycle.

So I wind up with low carbon dioxide and carbonate being returned to the system.

As a result I have a high pH (8.4+), KH of 4 degrees. and all fish including those requiring soft water thrive.

But that's just my .02