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Using Peat To Lower Water pH

Hi Folks,

Well, I thought things were getting a bit clearer. Until I read the following, which is a word-for-word extract from Diana Walstad's book Ecology of the Planted Aquarium:

"I would caution hobbyists to use water hardness whenever possible to classify their tapwater. It is the water hardness, not the pH or the alkalinity that counts". This is stated in the context of water as a source of plant nutrients. To me, this appears to directly contradict what is being said on the 2HR Aquarist site linked above". Yes/No? What am I missing?

JPC
 
The 2hr Aquarist page linked states that hardness is more important than pH, which is essentially what D. Walstad is saying - is this correct or am I barking up the wrong tree?

KH fluctuations affect livestock as changes in carbonate salt concentrations impact osmotic functions in livestock. This flux will be shown as changes in the pH as well. So pH changes due to KH changes will affect livestock, but pH changes with no change in KH will not.


To this end, it is KH stability that matters much more in aquariums rather than pH stability. With the stability of the later (pH) being important only as an indication of stability of the former (KH).


Why all the emphasis on pH then?


It is more an effect of historical precedence than anything else; pH is easy to test for and understand, while testing for KH requires titration. With the improved understanding of today's science, we should shift our emphasis more onto paying attention to KH rather than pH because that is what ultimately affects livestock/plants.
Common plant species that are not picky can be grown in much more alkaline water pH8+. To narrow it down and be more specific where picky species are concerned, read the article on KH (carbonate hardness) as that takes precedence over pH.
 
Also, regarding the original question see this article about how the author uses a peat moss filtering technique to treat tap water to significantly reduce pH and hardness before introducing it to the aquarium. I know this is slightly different to the original question but well worth a look:

Marksfish - How to Peat Filter Tap Water

Water comes out of the tap at a pH of 8.3 and with a carbonate hardness of 13, enough to stand a spoon in!! After filtering, the results are pH 5 and KH 3, quite a difference huh? As with reverse osmosis and other purification devices, it is necessary to rebuild your water to the required consistency using plain tap water. You will find that the filtered water is a "teas stained" colour. This is the tanins from the peat and is quite natural. Some people like me like the look (it is an acquired taste I grant you) as it makes the fish enhance their colouration. For those that don't like the look, a little bit of carbon run in the filter will soon clear it up.

I'm not going there on whether it is environmentally friendly or not.
 
Hi all,
that hardness is more important than pH, which is essentially what D. Walstad is saying - is this correct or am I barking up the wrong tree?
I think you are right, they are both interested in carbonate hardness (dKH). My guess is that they have slightly different reasons for homing in on carbonate hardness as the important factor.

In Diana Walstad's case she didn't originally change any water, so she was reliant <"on the carbonate buffer"> in the tank to avoid <"old tank syndrome">, with "old tank syndrome" mainly caused by the carbonate requirement of nitrification.

In the <"2hr Aquarists"> case they have noticed that when the pH falls due to changes in the CO2 ~ HCO3 equilibrium (when you add CO2) that this doesn't effect the livestock. In the "added CO2" scenario you have the <"same amount of dKH">, what has changed is the amount of <"Total Inorganic Carbon (TIC)">, due to the "spare" injected CO2.

If you keep soft water fish they are used to pH changes, because <"pH is inherently unstable in soft water">. As carbonate hardness increases those pH changes are damped down, as the pH stabilises near the pH8 carbonate equilibrium value. In really hard water the pH will always be alkaline <"and shell beds can develop">.

cheers Darrel
 
Hi @Maf 2500

I think the confusion arises here partly because of terminology:

From the 2HR Aquarist, "pH is tied closely to carbonate hardness (KH) which measures the amount of Carbonate (CO3) and bicarbonate (HCO3) ions in the water".

The key point here is the term 'carbonate hardness' - more correctly known as 'alkalinity'. So, the 2HR Aquarist is saying that KH (and therefore pH) are what's important in the water - if you happen to be a plant. But, Diana Walstad is saying that it's the (general) hardness (i.e. GH) that is the more important:

"It is the water hardness, not the pH or the alkalinity that counts."

JPC
 
Hi all,
is the term 'carbonate hardness' - more correctly known as 'alkalinity'.
It is back to all the confusing terms again, <"alkalinity"> and <"basicity"> are often used interchangeably, by they are actually slightly different. My guess is that what Diana Walstad actually used alkalinity when she meant basicity.
............Alkalinity roughly refers to the molar amount of bases in a solution that can be converted to uncharged species by a strong acid. For example, 1 mole of HCO31− in solution represents 1 molar equivalent, while 1 mole of CO3-− is 2 molar equivalents because twice as many H+ ions would be necessary to balance the charge. The total charge of a solution always equal zero. This leads to a parallel definition of alkalinity that is based upon the charge balance of ions in a solution.........
In most natural situation dGH, dKH, alkalinity and basicity are all interchangeable, because they are all measures of the amount of dissolved limestone (CaCO3) in solution. Limestone supplies 1 : 1 dKH and dGH. The <"derivations of all the units"> are in Larry Frank's article at <"the Krib">.

cheers Darrel
 
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Hi Folks,

I don't think I have a problem with what the 2HR Aquarist is saying. He is simply looking at pH and alkalinity. GH is not relevant to the topic that he is presenting. So, my difficulty lies with what Diana Walstad is saying. She seems to be dismissing pH and alkalinity as unimportant. Am I reading her wrongly? For anyone that doesn't have a copy of Diana Walstad's book, this will be difficult to follow. :eek:

JPC
 
In most natural situation dGH, dKH, alkalinity and basicity are all interchangeable, because they are all measures of the amount of dissolved limestone (CaCO3) in solution. Limestone supplies 1 : 1 dKH and dGH. The <"derivations of all the units"> are in Larry Franks article at <"the Krib">.
Thanks @dw1305 , to be honest I struggle a little with understanding (and memorising) all the differences between the various measures of hardness and alkalinity. It is good to know that in most cases they are interchangeable.

The one key difference that I understand between pH and any of the above is that pH varies with CO2 concentration while hardness/alkalinity will remain relatively unaffected. Therefore the absolute value of the pH is less important than water hardness for both livestock and plants.
 
Hi Folks,

Perhaps if I quote Diana Walstad's sentence immediately following on from that which I have referenced above:

"Although all three parameters are often correlated in nature, under artificial tapwater conditions they may not be".

JPC
 
So, my difficulty lies with what Diana Walstad is saying. She seems to be dismissing pH and alkalinity as unimportant. Am I reading her wrongly?

In terms of growing aquatics plants, which I assume is what she is referencing, then pH and alkalinity are largely unimportant aren’t they? KH only affects some plants, with some growing optimally in softer water, and some growing optimally in harder water.
 
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I was under the impression that some plants can use carbonate from the water if there's a lack of co2?
I'm sure I've read vallisneria is one of them but could have dreamt that.
 
In terms of growing aquatics plants, which I assume is what she is referencing, then pH and alkalinity are largely unimportant aren’t they?
Hi @Wookii

That is not my understanding. For example, on A N Other forum on which I am a member, a lot of importance is placed on water pH when growing aquatic plants. So, I will pursue this topic on there as well.

JPC
 
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Hi @Wookii

That is not my understanding. For example, on A N Other forum on which I am a member, a lot of importance is placed on water pH when growing aquatic plants. So, I will pursue this topic on there as well.

JPC

I’m not aware of anyone targeting a specific pH for aquarium plants John. Certainly for live stock, yes, and avoiding the extreme ends of the pH range possibly, but the 6.0-8.0 pH that most tanks sit at should be fine for the vast majority of plants. A pH above 7 can be an issue for nutrient delivery and breaking chelation but that not a plant issue, it’s a ferts issue.
 
I was under the impression that some plants can use carbonate from the water if there's a lack of co2?
I'm sure I've read vallisneria is one of them but could have dreamt that.

It is true I believe John, though I’m unsure to what extent the KH level is an actual ‘requirement’ for the plant to grow if it otherwise has sufficient CO2 I don’t know.
 
A pH above 7 can be an issue for nutrient delivery and breaking chelation but that not a plant issue, it’s a ferts issue.
Hi Gareth,

Ah, I think we're now getting to the crux of the matter. You are correct, of course. And iron (in)solubility is a good example of why water pH is important. In the case of iron, the answer is to add a chelator. This is all about our plants being able to take up the nutrients they need. So, water column and substrate pH are important considerations. The natural habitats of many aquatic plants have low/very low pH. In her book, Aquarium Plants, @Christel lists many locations in Thailand, India and Brazil where the water pH is less than 6.5, for example.

It would be interesting to know the water pH in which aquarium plants are cultivated by the likes of Tropica, AquaFleur, etc. My understanding is that they are grown hydroponically. That being the case, the optimum pH range of the hydroponic nutrient solution is 5.8-6.3, according to a few sources.

I want to reiterate that I am no expert in this field. I'm just a beginner who is keen to get some hard facts - I feel more comfortable with that.

JPC
 
I was under the impression that some plants can use carbonate from the water if there's a lack of co2?
I'm sure I've read vallisneria is one of them but could have dreamt that.
Hi @John q

It's not so much carbonates as bicarbonates. In alkaline water (pH>7.0), there isn't much CO2 in the water column as it takes the form of bicarbonates. And, you are correct - Vallisneria spiralis is one example of a bicarbonate user.

JPC
 
It would be interesting to know the water pH in which aquarium plants are cultivated by the likes of Tropica, AquaFleur, etc. My understanding is that they are grown hydroponically. That being the case, the optimum pH range of the hydroponic nutrient solution is 5.8-6.3, according to a few sources.
Hi Folks,

Is anyone able to shed any light (!) on the above?

JPC
 
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