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RO Water, Remineralizers and pH

jaypeecee

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Hi Folks,

For those people who use RO water + remineralizers, what resulting water pH do you get?

I just hope that I'm not the only one who uses RO water!

Any and all feedback very welcome!

JPC
 

Nick potts

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I use RO and remin but I have never checked the PH. I am sure there are a few on here who use RO

WC today so will check.

Is there a reason for wanting to know?
 

Conort2

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Either add some tap or a bit of equilibrium. Never measure the ph though just the tds.

cheers
 

dw1305

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Hi all,
For those people who use RO water + remineralizers, what resulting water pH do you get?
I don't use RO, but, if you add any dKH, the answer is always going to be ~pH8. This is because it is the pH value is set by the carbonate ~ CO2 ~ pH equilibrium, when CO2 levels are at ~415ppm.

ocean_acidif.jpg

From : <Ocean Acidification>. Sea water is carbonate rich and alkaline. Sodium chloride (NaCl) is a neutral salt, so it doesn't effect pH.

If you only add dGH, then it is a bit more complicated, because you have to take into account both cation and anion, with salts being either <"weak acids or weak bases">. Magnesium sulphate (MgSO4.87H2O) is a weak acid and calcium chloride (CaCl.2H2O) is a neutral salt ("the product of a reaction between a strong acid HCl and strong base Ca(OH)2)").

cheers Darrel
 
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dw1305

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Hi all,
Never measure the ph though just the tds.
That would be my suggestion, pH is a bit of a movable feast, but conductivity (or TDS) are much more straightforward.

If you use a proprietary mix (like "Seachem equilibrium"), or a <"DIY one">, just find the smallest addition that gives you healthy plants (with your usual nutrient addition) and then measure the TDS/Conductivity.

I use 80 - 120 microS <"as my datum figure">. There isn't anything magical about this, but that is about the conductivity value of our rainwater in summer and I can use our hard tap water (1 : 1 dGH : dKH) to raise the conductivity in the winter, when the rainwater is nearer to RO (down to about 30 microS).

cheers Darrel
 

Alex Papp

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Hi Folks,

For those people who use RO water + remineralizers, what resulting water pH do you get?

I just hope that I'm not the only one who uses RO water!

Any and all feedback very welcome!

JPC
I use Ca:Mg 3:1.
GH= 5
KH= 0
pH= let's not get confused lol (it changes a lot)
I use Brightwell aquatics Calcion and Magnesion and add them so the Ca:Mg is in a 3:1 ratio. As others have pointed out, it isn't the cheapest way of doing it.
I like a solution as I can measure it precisely unlike a powder. This is what I'll use when it runs out:

I saw the other thread with all the confusion. I'm studying pH at the moment at school and it is very confusing. Even H2O can combine with an H from another H2O into H3O+, and pure water becomes acidic by itself at high temperatures...help! Just stick to a remineralising method somone else is doing and getting good results.
 

jaypeecee

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I don't use RO, but, if you add any dKH, the answer is always going to be ~pH8. This is because it is the pH value is set by the carbonate ~ CO2 ~ pH equilibrium, when CO2 levels are at ~415ppm.
Hi Darrel (@dw1305)

Of course, what a dummy I am! So, if I want to achieve a water pH that would be more suited to my plants (say, pH=6), what's the best way to do it? I can't rely on CO2 bridging the gap (a 2.0pH reduction), so do you have any suggestions? Or am I simply overlooking something here?

JPC
 

dw1305

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jaypeecee

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Probably start with RO and don't add any carbonate hardness (dKH)? I'd guess @Roland is <"the person you need to talk to">, as he seems to have mastered the art of growing "difficult" (not for him) <"soft water plants">.
Hi Darrel,

Does that mean that most people don't grow soft water plants? Reading Ecology of the Planted Aquarium*, I was under the impression that most people grow soft water plants. No?

* Diana Walstad

JPC
 

Nick potts

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Hi Darrel,

Does that mean that most people don't grow soft water plants? Reading Ecology of the Planted Aquarium*, I was under the impression that most people grow soft water plants. No?

* Diana Walstad

JPC

Most soft water plants will do fine in harder water, there are some species that do better in soft water such as Tonina species (which Roland is very good at growing), but it doesn't mean you can't grow them in harder water.
 

jaypeecee

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Is there a reason for wanting to know?
Hi @Nick potts

Yes, rightly or wrongly, I am led to believe that most aquarium plants grow best at a pH of 6 - 7. Please take a look at:


JPC
 

jaypeecee

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Most soft water plants will do fine in harder water, there are some species that do better in soft water such as Tonina species (which Roland is very good at growing), but it doesn't mean you can't grow them in harder water.
Hi @Nick potts

Many thanks for your valuable feedback. Since I started growing plants in my tanks, I have found it difficult to find out which plants are categorized as soft water plants and which are considered to be hard water plants. And it's not uncommon for aquarium plant suppliers to disagree on which category they fall into.

JPC
 

dw1305

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Hi all,
Does that mean that most people don't grow soft water plants?
I was under the impression that most people grow soft water plants
I think it is probably the same as for fish, most popular plants will grow in hard or soft water. That is why they are popular they tend to grow, rather than die, when you put them in the tank.

You are less likely to have issues with nutrient availability in softer water, and it would allow you to grow a wider range of plants.

cheers Darrel
 

Wookii

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Hi @Nick potts

Yes, rightly or wrongly, I am led to believe that most aquarium plants grow best at a pH of 6 - 7. Please take a look at:


JPC

As mentioned in the other thread John, pH is largely irrelevant in the context of growing plants in an aquarium. There are many many tanks on this forum with lush extensive plant growth in non-CO2 injected tanks that likely always run a pH above 7. There are some plants that require soft water such as with those in Rolands tank as Darrel has pointed out, but that requirement relates specifically to the KH, not the pH - as evidenced by the fact that I have tried growing some of Rolands Tonia from that very tank, in my own tank. Despite my tank pH almost always being below 7, it wouldn't grow and slowly wilted away because I'm unable to maintain a KH low enough (CaCO3 in the Sieryu stone in the tank pushes my KH constantly above 6 as it is dissolved by the acidic water).

The importance of KH over pH is actually detailed in the article you linked to:

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.

If you also look in the table of measurements in that article from a natural soft water lake, the pH spends a decent proportion of its time above 7 as the plants soak up the CO2, and it is only the CO2 accumulation that brings it back down again:

phco2flux.jpg
 

jaypeecee

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...most popular plants will grow in hard or soft water.

Thanks, Darrel (@dw1305)

I realize that this will no doubt appear to be a silly question but would you mind - off the top of your head - listing what you consider to be the "most popular plants"? This is not a trick question - I'm openly declaring that I do not know the answer to this question. Let me give you an example - like many other people, I have attempted to successfully grow Amazon Swords. All the blurb led me to believe that even a child could grow these. I grew them in soft water because I associated the Amazon with soft water. But, according to Diana Walstad, Swords don't grow well in soft water because there's not enough calcium in the water*.

* Ecology of the Planted Aquarium, Third Edition, pp 86 - 87

JPC
 

jaypeecee

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...pH is largely irrelevant in the context of growing plants in an aquarium.

Hi Gareth (@Wookii)

And, yet, the loud-and-clear message on A N Other reputable forum places a lot of importance specifically on water pH. I realize that it would be easy to say - well, they've got it wrong. And, the 2HR Aquarist recommends a pH range from 6 to 7. Furthermore, @Christel recently said "The emersed plants are in a heavily fertilized nutrient solution (I once measured over 1000 µS/cm a few years ago). The pH will be acid so that the nutrients can be absorbed". Please see:


So, I'm confused.

JPC
 

Wookii

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Hi Gareth (@Wookii)

And, yet, the loud-and-clear message on A N Other reputable forum places a lot of importance specifically on water pH. I realize that it would be easy to say - well, they've got it wrong. And, the 2HR Aquarist recommends a pH range from 6 to 7. Furthermore, @Christel recently said "The emersed plants are in a heavily fertilized nutrient solution (I once measured over 1000 µS/cm a few years ago). The pH will be acid so that the nutrients can be absorbed". Please see:


So, I'm confused.

JPC

You can link to and name other forum sources John, there's no rule against it on UKAPS.
 

Wookii

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Hi Gareth (@Wookii)

And, yet, the loud-and-clear message on A N Other reputable forum places a lot of importance specifically on water pH. I realize that it would be easy to say - well, they've got it wrong. And, the 2HR Aquarist recommends a pH range from 6 to 7. Furthermore, @Christel recently said "The emersed plants are in a heavily fertilized nutrient solution (I once measured over 1000 µS/cm a few years ago). The pH will be acid so that the nutrients can be absorbed". Please see:


So, I'm confused.

JPC

As mentioned before, the acidification of the growing medium for a commercial outfit will be to prevent some micro elements, such as iron, from becoming unavailable not because the plants specifically need an acid pH in order to grow - that is what Christel is likely referencing. A commercial outfit will be concerned only with bottom line, and that is maximised by keeping costs down and maximising plant growth. So collecting free rainwater, and maintaining a lower pH so they don't have to use fertilisers with more expensive chelates, or risk reduced plant growth from certain elements becoming unavailable, will be important to minimising costs. It's one of the reasons (along with durability of the final plant) why the majority of the plants are grown emersed rather than submerged - free unlimited CO2!

The 2hr aquarist doesn't 'recommend' a pH of 6 to 7 as a target for plants, that is just the result from a low (2-6) KH and CO2 injection that he does recommend. Far and away the overriding message from that article is that pH doesn't matter, but KH matters in some cases.
 
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