Why are there pH recommendations?

[BlueRaccoon]

When I research fish I spend a lot of time doing it, and I've always taken information about pH into account. But it is extremely common to see people who say they have had a fish in a completely different pH for years, and they have thrived. If most fish can handle such a large range, why is it even recommended? I have intentionally avoided fish I'd love to have because I don't have acidic water. But I'm often told that doesn't matter.

 

[TClare]

I am not sure pH is as important as hardness and TDS/conductivity, but normally these are related to a degree, soft water usually has a pH of 7 or below, whereas hard water tends to have higher pH. I strongly believe that fish should be be kept in conditions as close as possible to their natural habitat, and many cases of diseases can be explained when it turns out that soft water species are being kept in hard water and vice versa. How sensitive species are to the "wrong" parameters will depend to an extent on their natural distribution. Species that are widespread and found in a variety of water types will be much less sensitive than say strict blackwater species that only occur naturally in very soft, acidic water with negligible conductivity. These are very sensitive to bacterial infections that they do not encounter naturally in their habitats. Fish that occur in hard water have osmotic issues in soft water. Many people say that it really doesn't matter for fish that have been bred for many generations in captivity, and that they can adapt to virtually any parameters. While obviously these are much less sensitive than wild caught fish, and many will survive if well kept, still their overall health, colouration, resistance to disease, longevity etc. are going to be be far super in water that is close to natural conditions for the species. Many generations of captive breeding does not replace millions or at least hundreds of thousands of years of evolution and adaptation. In my opinion it is important to choose species best suited to your water parameters.

 

[ruud]

pH is just difficult to understand.

Average pH is between 7 and 8, determined by natural CO2 diffusion and the presence of (bi)carbonates/KH. Due to additional acids released naturally in an aquarium, it will have a tendency to go towards 7, but I would treat any pH between 7 and 8 similarly.

Like TClare I like to give fish an environment that resemble their origins.

Most fish in the hobby prefer soft water which is between 6 and 7. Reducing (bi)carbonates/KH will allow the same acids to bring the pH in this range. I don't really care if it is 6.2 or 6.9; I regard it as similar.

Going below 6 is difficult. Bicarbonates need to be 0 or almost 0 and dead terrestrial matter has to be added (cones, pods, leaves, wood).

I'm sure people can keep the average tetra in neutral pH water (between 7 and 8).

There are just many things we don't know. The strongest guideline I follow is to keep the fish's environment as close as possible to its origins. I've never seen a fish disease in my life. Perhaps this is attributable to the guideline.

+++++++++++

One more thing: I believe there is a major difference between adult fish and fry and juveniles. It is a bit similar to temperature. Most recommended temperatures are actually 'breeding temperatures'. Because the fish breed at certain temperatures, it has to be the right temperature for this species. This is wrong thinking. It is the right temperature for breeding, but not the right temperature to keep fish in all year.

This is a little how I treat other water parameters also. Parameters can be critical for breeding and raising, but for the adult's well-being I believe it matters less. Various studies I believe have shown this also to be the case for pH.

Again, because of all the gaps in knowledge, I stick to my one guideline.

 

[StarGirl]

Most people dont know if their fish are wild caught or farm raised. The lfs probably doesnt know either most times, especially the chains. I have heard many times around here that a lot of the lfs get fish from farms in Florida which hails the same great 8.0 water as many of us have.

I guess what I am saying is how do you even know if your fish were bred/raised in their "native" pH range?

 

[BlueRaccoon]

Thank you both. I'm probably going to need to reread both responses a couple of times, lol.

See, I have a pH of around 7.6-7.8, but my water is relatively soft. I don't know my gh or kh right now, but it's usually around 5ish or less. So I keep fish that are ok being at my pH, usually I'm at the top of their range, but my water is softer, so I wonder if this is acceptable? The only health problems I have seen are genetic organ failure with one specific group of a specific species. I don't see this problem in a different bloodline of the same species.

I'm trying to just get a grasp of this knowledge, because I want to provide the most healthy environment possible for my fish.

Most people dont know if their fish are wild caught or farm raised. The lfs probably doesnt know either most times, especially the chains. I have heard many times around here that a lot of the lfs get fish from farms in Florida which hails the same great 8.0 water as many of us have.

I guess what I am saying is how do you even know if your fish were bred/raised in their "native" pH range?

Sure, that's a good point. And I would assume that most of the common fish seen in the trade are farm raised, with a few exceptions like otos.

However, I guess what I have wondered if why are these ranges even recommended if so many people don't follow them, and does years of evolution in specific conditions still have some effect.

 

[NotSoAggressiveAquatics]

My best advice is unless you are keeping a fish that is a super well known “look at it wrong and it dies” type of fish then stability is much more important than perfect ph. There are exceptions to this though don’t go getting whatever fish you want that needs a ph of 8 and you have 6.5. I’d try and keep it within .5 to 1 max and they’ll be just fine

 

[BlueRaccoon]

My best advice is unless you are keeping a fish that is a super well known “look at it wrong and it dies” type of fish then stability is much more important than perfect ph. There are exceptions to this though don’t go getting whatever fish you want that needs a ph of 8 and you have 6.5. I’d try and keep it within .5 to 1 max and they’ll be just fine

Right....the only fish I have kept outside of the recommended range were like 0.2 off. But that wasn't intentional. My tap water changed.

 

[ruud]

See, I have a pH of around 7.6-7.8, but my water is relatively soft. I don't know my gh or kh right now, but it's usually around 5ish or less.

A pH of 7.8 matches the CO2 - carbonate - pH equilibrium. It is as average as average can get.

pH is technically neutral at 7. But this holds for pure water.

A tiny bit of pure water, H2O, falls apart in H+ and OH- ions in equal amounts. This is what pH refers to. In equal amounts it is 7.

Then atmospheric CO2 enters pure water, and relatively more H+ ions are released. The pH drops to 5.5.

That's a major drop based on only a very weak acid (carbonic acid) resulting from CO2 diffusion!

If your water contains only a little bicarbonates (KH 1+), this surplus of H+ ions is captured by bicarbonates. A chemistry scientist is laughing right now, but I'm just trying to paint a simple picture.

Why is pH oftentimes around 7.8? Because all the H+ ions are captured by bicarbonates. What do we have left?

OH- ions on the other side of the ratio!

Hence pH typically stabilises around 7.8 if your water contains some bicarbonates.

Unless..... more acids are released. Bacteria in your aquarium will take care of this. As a result, more H+ ions are released and the equilibrium shifts downwards on the pH scale.

So you are worrying too much. And you don't really have soft water so it seems.
If you want to get to the 6 - 7 pH zone, you need to dilute your water in order to lower the bicarbonates.

Worrying about a pH of 6.3 versus 6.9 is plain silly. Your tank is alive. It is constantly fluctuating a bit, like the sun that is sometimes strong, but sometimes clouds pass by and the sun is gone for a while. Nature isn't being slaughtered due to a few clouds passing by...

Edit: I assume you are aware that pH is expressed on a log scale. Hence, a pH of 6.3 versus 6.7 is much smaller than a pH of 6.7 versus 7.1. Hence, thinking in zones (6-7 = soft, 7-8 = neutral, 8-9 = hard) makes sense.

 

[SparkyJones]

I think it really matters when it comes to breeding and the species thriving in captivity vs. Never breeding and then eventually dying off. I'd say wherever there is water and fish there's going to be rain and that rain is going to come down pure and hit the water and dilute, and hit the ground nearby and run off nutrients into the water.

You may have fish that breed in the rainy season, or in the dry season, in which case the pH and TDS and all that changes and it induces the spawning.
I think as far as the fish go, they adapt for the rains and dry spells, and can make these swings and acclimate to survive, but if locked in they don't get the trigger to spawn of ideal conditions and they just don't "thrive" which is what most people keeping fish strive for, to recreate their environment so they can live a full life.

I also think a lot of people don't consider any of this, and look at it as some invisible or magical thing, even their "cycle". It works, and when it doesn't, then it doesn't work and question what went wrong... or don't question it and just go get more fish.

I wouldn't call "surviving", as "thriving" though. I think to thrive you have to be able to have full life cycles, ability to maintain a population.

 

[BlueRaccoon]

Thanks everyone. I guess I need to go read about this stuff and then read about the affects hardness.

I was a chem major for 3 years, and it's like my brain just dumped it all. But that seems to be how my brain works. If it doesn't need it, it's gone, haha.