Clearing up a couple misconceptions

  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
First, there's the misconception that ammonia is only above a pH of 7 and only ammonium is present below a pH of 7. I have no clue where this came from. Due to the acid dissociation constant of ammonia/ammonium, the ammonium and ammonia concentrations are equal at a pH of about 9.23. Then for every ph drop of 1, the ammonium concentration becomes 10 times that of ammonia. For example, with a total ammonia concentration of 1 PPM at a pH of 9.23, the ammonia and ammonium concentrations are each 0.5. But at a pH of 8.23, the ammonium would be 0.91 and the ammonia would only be 0.09. And at a pH of 7.23 (closer to typical aquarium pH), the ammonium would be 0.991 and the ammonia would only be 0.009. It's not a magical switch from ammonium to ammonia as many have been saying in various threads.
**For the most part, this is a moo point as your ammonia should always be 0 anyway. But to say that only ammonium is present below a pH of 7 is false and I need to correct that. Ammonia may be extremely low at those levels but values as low as .005ppm of free ammonia has shown to have detrimental effects on fish.


Another misconception is that doing two separate 50% water changes is identical to a single 100% water change. Each time you do a water change you're diluting the dirty water with clean water. So if you do a 50% water change, you're putting back in the same amount of clean water. When you do your next 50% water change, you're only removing 25% of the original dirty water because it was diluted so it's only identical to a 75%WC. Instead of 4 separate 25% water changes to get to 100%, you would actually need to do 11 just to get to 95%. Understanding your partial water changes is vital for proper waste export.


I realize some people who have given this false information in the past may take offense, but I'm hoping they understand that I'm just trying to help. The most important thing about fishkeeping is maintaining proper water conditions and you can't do that with false information.
 

izzyfishfarmer

Well Known Member
Messages
511
Reaction score
3
Points
113
Experience
Just started
good advice the truth hurts everyone but the fish
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
Thanks izzy
 

izzyfishfarmer

Well Known Member
Messages
511
Reaction score
3
Points
113
Experience
Just started
being a bigginer its much harder for me to weed out the good and the bad info and even harder to help people when I'm passing on the bad so i find myself constantly researching any advice I'm given
 

jetajockey

Fishlore VIP
Messages
6,744
Reaction score
97
Points
293
Experience
More than 10 years
The first part, I'm not sure where it came from either, but likely because at a low enough PH the amount of ammonia is negligible, so someone just gave a basic cutoff number rather than going to the effort to explain the process.

For the second part, that's just common sense, but I would still advocate 2 50% water changes over the course of 2 days rather than 1 100% water change. I would go into detail but I'm pretty sure that you understand the reasoning behind that.

Thanks for posting this, you've made some good points. Take care!
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
jetajockey said:
The first part, I'm not sure where it came from either, but likely because at a low enough PH the amount of ammonia is negligible, so someone just gave a basic cutoff number rather than going to the effort to explain the process.
My point was that you should never really ignore your ammonia reading at a lower pH. I couldn't find any study showing that at a certain pH, fish are completely safe from ammonia poisoning. I have, however, found multiple studies showing that levels that we may find miniscule and negligible like 0.005 mg/L is still harmful to fish. I'd rather nobody even explained how ammonia turns into ammonium as the pH lowers (I only did to correct the false information) because it's better to just keep ammonia at zero and not consider that some of it might be the less harmful ammonium.

jetajockey said:
For the second part, that's just common sense, but I would still advocate 2 50% water changes over the course of 2 days rather than 1 100% water change. I would go into detail but I'm pretty sure that you understand the reasoning behind that.
Of course I'm not recommending doing 100% water changes. That was just an example to show that the smaller the water change, the more you need to do in order to remove a certain mass of waste.

jetajockey said:
Thanks for posting this, you've made some good points. Take care!
Thanks jetajockey ;D
 

bolivianbaby

Fishlore Legend
Messages
12,169
Reaction score
69
Points
293
Experience
5 years
funkman262 said:
First, there's the misconception that ammonia is only above a pH of 7 and only ammonium is present below a pH of 7. I have no clue where this came from. Due to the acid dissociation constant of ammonia/ammonium, the ammonium and ammonia concentrations are equal at a pH of about 9.23. Then for every ph drop of 1, the ammonium concentration becomes 10 times that of ammonia. For example, with a total ammonia concentration of 1 PPM at a pH of 9.23, the ammonia and ammonium concentrations are each 0.5. But at a pH of 8.23, the ammonium would be 0.91 and the ammonia would only be 0.09. And at a pH of 7.23 (closer to typical aquarium pH), the ammonium would be 0.991 and the ammonia would only be 0.009. It's not a magical switch from ammonium to ammonia as many have been saying in various threads.
**For the most part, this is a moo point as your ammonia should always be 0 anyway. But to say that only ammonium is present below a pH of 7 is false and I need to correct that. Ammonia may be extremely low at those levels but values as low as .005ppm of free ammonia has shown to have detrimental effects on fish.


Another misconception is that doing two separate 50% water changes is identical to a single 100% water change. Each time you do a water change you're diluting the dirty water with clean water. So if you do a 50% water change, you're putting back in the same amount of clean water. When you do your next 50% water change, you're only removing 25% of the original dirty water because it was diluted so it's only identical to a 75%WC. Instead of 4 separate 25% water changes to get to 100%, you would actually need to do 11 just to get to 95%. Understanding your partial water changes is vital for proper waste export.


I realize some people who have given this false information in the past may take offense, but I'm hoping they understand that I'm just trying to help. The most important thing about fishkeeping is maintaining proper water conditions and you can't do that with false information.

The ammonium information partially came from me. There are two types of ammonia that are tested. The free ammonia is the toxic part of the TAN (Total Ammonia Nitrogen).

The above information came from:

This information is used to help cycle tanks faster, not telling people to "ignore" ammonium and put their fish at risk.

Below 6.0, the nitrifying bacteria dies, which can cause a cycle to crash. Nitrifying bacteria optimum growth PH is between 6 and 9. Above 9, the nitrifying bacteria dies. Below 6, the nitrifying bacteria dies.

I agree, all ammonia is toxic to fish. However, ammonium is less toxic than ammonia since it doesn't contain as much free ammonia.

Let's face it: the nitrogen cycle is the most aggravating part of fishkeeping and starting a new tank.

I'm looking for the article regarding the ammonium in regards to TAN. When I find it, I'll post it. That'll explain things further.
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
bolivianbaby said:
This information is used to help cycle tanks faster, not telling people to "ignore" ammonium and put their fish at risk.
I'm sorry but I don't understand how telling people that ammonia doesn't exist below a pH of 7 helps to cycle a tank. Please ellaborate...
 

jetajockey

Fishlore VIP
Messages
6,744
Reaction score
97
Points
293
Experience
More than 10 years
To go with this topic, Seachem makes a tester that differentiates between free ammonia and ammonium, in case anyone was looking.


....thus is the only kit on the market that can read levels of free ammonia while using ammonia removal products such as Prime®, Safe™, AmGuard™ and any similar competing products. The other kits (salicylate or Nessler based) determine the total ammonia by raising the pH of the test solution to 12 or greater. At this high pH all ammonia removal products will breakdown and rerelease the ammonia, thus giving you a false ammonia reading.
just some extra food for thought
 

bolivianbaby

Fishlore Legend
Messages
12,169
Reaction score
69
Points
293
Experience
5 years
funkman262 said:
I'm sorry but I don't understand how telling people that ammonia doesn't exist below a pH of 7 helps to cycle a tank. Please ellaborate...
I've never stated that ammonia doesn't exist below a PH of 7. The free ammonia is greatly reduced below a PH of 7 and pretty much ceases to exist below 6.0.

The free ammonia contains the necessary bacteria for the nitrites to "feed on". As you well know, that's an important aspect of the nitrogen cycle.

As the PH rises, the free ammonia level rises. To cycle a tank faster (fishless only preferably the free ammonia rises the higher the PH), the higher PH (and also higher temps-but that's another story) will provide the necessary bacteria for the nitrites to feed on, which will provide the nitrates with the nitrites to feed on.

When cycling with fish, of course daily water changes are necessary to keep the ammonia levels as low as possible, but the free ammonia must exist in the tank in order for the nitrifying bacteria to develop to complete the nitrogen cycle.

Once the nitrogen cycle is complete, the stress to the fish is greatly reduced (provided stocking is compatible, etc.)
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
bolivianbaby said:
I've never stated that ammonia doesn't exist below a PH of 7.
If you go back to the original post, that's the issue that I was bringing up...
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
jetajockey said:
To go with this topic, Seachem makes a tester that differentiates between free ammonia and ammonium, in case anyone was looking.




just some extra food for thought
Thanks for this information. Although that sounds like a useful product, I don't see the need to differentiate between free and ionized ammonia. Both are detrimental to the fish. If your total ammonia is 0.5 ppm, the way I see it is that instead of trying to figure out how much of it is free ammonia, you should just worry about how to get it to zero.

As far as cycling the tank, you have ammonia that gets converted to nitrite and eventually to nitrate and then your tank has completed cycling after the ammonia and nitrite are zero while the nitrates continue to steadily increase. Again, who cares how much of the total ammonia is free ammonia or ammonium?

I've only brought this up because I major in environmental engineering which is pretty much nothing but water chemistry and biology. The bacteria that we refer to as BB or benificial bacteria are the same microorganisms that wastewater treatment plants use in their aerobic reactors for nitrification. I'm not trying to argue with anyone here, simply straighten out a couple things that I continue to see in various threads that aren't true.
 

jetajockey

Fishlore VIP
Messages
6,744
Reaction score
97
Points
293
Experience
More than 10 years
I think the only real application it would have is for reference to better optimize someone's detoxifier dosing amounts.
 

bolivianbaby

Fishlore Legend
Messages
12,169
Reaction score
69
Points
293
Experience
5 years
funkman262 said:
If you go back to the original post, that's the issue that I was bringing up...
I've never seen anyone saying that ammonium isn't toxic on the forum, just that it's not as toxic. I felt it was a possible misunderstanding or misinterpretation, so I thought I'd clarify.
 

sirdarksol

Fishlore Legend
Messages
13,062
Reaction score
253
Points
383
Experience
3 years
bolivianbaby said:
I've never seen anyone saying that ammonium isn't toxic on the forum, just that it's not as toxic.
I have seen it (extremely rarely, as few people bother to bring up the idea of using pH to play with ammonia... it's more hassle than it's worth, unless your ph is so low as to inhibit the nitrogen cycle, an issue very few people have), but there are also always a number of people (myself included) who will correct the misconception.

I also haven't really noticed anybody saying "two 50% water changes are equal to 1 100% water change." I was "corrected" on it a month or so ago, but I was just giving a vague example of numerous water changes over a week, and hadn't bothered to do the math (because the math wasn't important, it was the concept of numerous water changes in a week that was important). Other than that, I haven't noticed anyone around here saying much about it.
 
  • Thread starter

funkman262

Well Known Member
Messages
890
Reaction score
20
Points
113
Experience
1 year
sirdarksol said:
I also haven't really noticed anybody saying "two 50% water changes are equal to 1 100% water change." I was "corrected" on it a month or so ago, but I was just giving a vague example of numerous water changes over a week, and hadn't bothered to do the math (because the math wasn't important, it was the concept of numerous water changes in a week that was important). Other than that, I haven't noticed anyone around here saying much about it.
I'm not saying that it is said everyday. Just trying to point out that when you're doing multiple water changes in a short amount of time, you need to consider that you may not be removing as much of the old water as you think. The 50% was more of a generalization (even though I have seen it said more than once). Sorry if I made it sound like I'm constantly seeing that said. I'm not necessarily trying to just correct everyone, I'm just trying to get everyone to understand these two simple concepts a little better (especially those that are new to fishkeeping and not familiar with water chemistry).
 
Toggle Sidebar

New Threads

Similar Threads

Aquarium Calculator

Aquarium Photo Contests

Follow FishLore!

FishLore on Social Media





Top Bottom