Who Gives A Fish Forums

I've made some progress in understanding "water" since I restarted my aquariums. At first glance, it seems straightforward, but things get complicated when you start dealing with specialty fish and areas. I was looking at a particular fish the other day that apparently likes medium hard water with low pH. If I'm not mistaken, that got me thinking - could there be dissolved solids other than calcium that contribute to water hardness, but the presence of leaf litter somehow lowers the pH?

I'm also curious about how calcium affects pH - does it buffer it towards alkaline, acidic, or does it just try to maintain that 7.0 pH? I'm finding more unusual fish interesting, and I'm sure that as long as you get the hardness and pH close enough, the fish will survive. However, if you're trying to breed them, which I might be interested in doing after I retire, pH could make all the difference in whether something breeds successfully.

bettaMagenta wrote: ↑Sat Jan 20, 2024 1:06 pm I've made some progress in understanding "water" since I restarted my aquariums. At first glance, it seems straightforward, but things get complicated when you start dealing with specialty fish and areas. I was looking at a particular fish the other day that apparently likes medium hard water with low pH. If I'm not mistaken, that got me thinking - could there be dissolved solids other than calcium that contribute to water hardness, but the presence of leaf litter somehow lowers the pH?

I'm also curious about how calcium affects pH - does it buffer it towards alkaline, acidic, or does it just try to maintain that 7.0 pH? I'm finding more unusual fish interesting, and I'm sure that as long as you get the hardness and pH close enough, the fish will survive. However, if you're trying to breed them, which I might be interested in doing after I retire, pH could make all the difference in whether something breeds successfully.

I think I was reading about this the other day, and I'm pretty sure it's actually carbonates, or KH, that act as the buffer in water, right? Not just calcium, that's what I was getting at earlier... seems like that's what helps maintain the pH level, rather than just calcium on its own.

Carbonates, like those found in KH, are what I'd consider temporary hardness - it's the stuff that precipitates out of the water and has a significant impact on pH. On the other hand, you've got chlorides, which are a type of permanent hardness, comprised of calcium and magnesium. This type doesn't precipitate and has a relatively minor effect on pH.

Now, water can be made up of varying proportions of both calcium and magnesium, along with carbonates and chlorides, plus a whole host of other minerals. Carbonates are great at buffering and are bioavailable to certain organisms, while chlorides play a crucial role in maintaining osmotic balance and are essential for certain fish with specific requirements.

I've found that botanicals have a pretty negligible impact on water hardness. They might interact with carbonates to some extent, but it's a temporary and minor effect at best. That being said, they can have a more lasting impact in already soft water. For the critters in our tanks, botanicals serve as a food source and provide low molecular weight acids like formic, acetic, lactic, oxalic, and malic, which contribute to their overall well-being. Under aqueous conditions, these acids don't react much with chlorides and only lightly with carbonates.

kokomo wrote: ↑Sat Jan 20, 2024 7:23 pm Carbonates, like those found in KH, are what I'd consider temporary hardness - it's the stuff that precipitates out of the water and has a significant impact on pH. On the other hand, you've got chlorides, which are a type of permanent hardness, comprised of calcium and magnesium. This type doesn't precipitate and has a relatively minor effect on pH.

Now, water can be made up of varying proportions of both calcium and magnesium, along with carbonates and chlorides, plus a whole host of other minerals. Carbonates are great at buffering and are bioavailable to certain organisms, while chlorides play a crucial role in maintaining osmotic balance and are essential for certain fish with specific requirements.

I've found that botanicals have a pretty negligible impact on water hardness. They might interact with carbonates to some extent, but it's a temporary and minor effect at best. That being said, they can have a more lasting impact in already soft water. For the critters in our tanks, botanicals serve as a food source and provide low molecular weight acids like formic, acetic, lactic, oxalic, and malic, which contribute to their overall well-being. Under aqueous conditions, these acids don't react much with chlorides and only lightly with carbonates.

I'm completely lost after the first sentence, I think I need a refresher on some of these concepts.

By the way, I wasn't trying to sound like an expert, I'm still figuring things out myself

I'm stuck in this research loop with you guys, and I'm okay with that - as long as I have a good grasp of what I'm doing, I'm confident I'm not way off.

I've been thinking, what if we shift the focus from chemistry to the natural conditions that create these water parameters. We touched on stagnant water with lots of leaf litter earlier, but I'm curious about other scenarios.

For instance, in natural "soft" water, I assume it's just a matter of the water not being exposed to materials that make it alkaline. So, the mud or sand in these areas must be composed of harder minerals that don't leach into the water like limestone does.

I've also been wondering, if rainwater makes up a major portion of the water in creeks and streams, wouldn't that naturally result in softer water compared to lakes or stagnant water that collects minerals?

Water's hardness is largely determined by the materials it comes into contact with after falling as rain. For example, if it flows over granite, the resulting water will be soft, as granite barely dissolves at all. This is why areas like Cornwall in the UK, with its granite substrate, tend to have soft water.

On the other hand, rocks like chalk and limestone, which are rich in calcium carbonate, dissolve more easily, resulting in hard water. This is why people living in south east England often have tap water that's essentially "liquid rock".

In areas with high levels of decaying plant matter, like the Amazon basin, the water tends to be very soft and acidic. This is due to the way these organic materials interact with the water.

In general, tap water tends to be either soft and acidic or hard and basic. However, there are cases where the water is soft but has a high pH, or hard but has a low pH. The key factor here is the mineral composition of the water, which affects the pH, KH, and GH.

Hard water is characterized by a high level of divalent metal ions, mainly calcium and magnesium, with smaller amounts of other ions. Soft water, on the other hand, has few of these ions. The hardness of water is often expressed in terms of calcium carbonate or calcium, but this doesn't mean that's the only factor at play. It's more of a way to standardize the measurement.

KH, or alkalinity, is a measure of the amount of acid needed to lower the pH of a given volume of water to 4.5. It's essentially a measure of the buffering capacity of the water, which is mainly due to the presence of carbonates and bicarbonates. A high KH value indicates a stable pH, while a low value means the pH is more easily changed.

To illustrate this, consider a scenario where the water is high in calcium, making it hard. If it also contains a lot of carbonate, the KH will be high. However, if the water contains chloride instead of carbonate, the KH will be low. In this case, the pH may be low, even though the water is technically hard due to its high calcium content.

I think a bit of geology knowledge goes a long way in understanding this stuff. I recall exploring molly habitats and noticing the fine white dust everywhere - it was clear the land was uplifted sea bed with a lot of worn and dry limestone and coral. In contrast, the Amazon has rocks that have been landlocked for ages, so there aren't many minerals left to leach out of them. The intense rainfall and weathering over millennia have pretty much taken care of that.

When we talk about 100ppm water, it's not like we have 100ppm of the same minerals. For hobbyists like us without labs or fancy equipment, I think we just have to aim for being close. It's not a foolproof approach, but it usually works. We're essentially trying to read complex water with pretty basic tools.

I was wondering about this, sSjey - if the KH value is made up of minerals other than just calcium carbonate, does it still act as a buffer and resist pH change, or is it less effective than a high KH value that's mainly calcium carbonate?