# RO Water, Remineralizers and pH



## jaypeecee (21 Mar 2021)

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


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## Nick potts (22 Mar 2021)

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?


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## Conort2 (22 Mar 2021)

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

cheers


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## dw1305 (22 Mar 2021)

Hi all,


jaypeecee said:


> 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.





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 (22 Mar 2021)

Hi all, 


Conort2 said:


> 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


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## Alex Papp (22 Mar 2021)

jaypeecee said:


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


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: 








						HydRO 0/5 , Reverse osmosis (RO) water mineralizer  | eBay
					

Find many great new & used options and get the best deals for HydRO 0/5 , Reverse osmosis (RO) water mineralizer at the best online prices at eBay! Free delivery for many products.



					www.ebay.co.uk
				




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.


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## jaypeecee (22 Mar 2021)

dw1305 said:


> 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


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## dw1305 (22 Mar 2021)

Hi all,


jaypeecee said:


> 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?


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">.





cheers Darrel


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## jaypeecee (22 Mar 2021)

Alex Papp said:


> I'm studying pH at the moment at school and it is very confusing.


Hi @Alex Papp 

It's 50 years ago since I did 'A' level chemistry so that's my excuse for forgetting some of this stuff!

JPC


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## jaypeecee (22 Mar 2021)

dw1305 said:


> 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


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## Nick potts (22 Mar 2021)

jaypeecee said:


> 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?
> 
> ...



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.


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## jaypeecee (22 Mar 2021)

Nick potts said:


> 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:









						Is pH important in a planted aquarium ?
					

What is pH? Does it matter in a planted aquarium and what range is a good target if so ? This page explains what pH reading means to your planted tank setup.




					www.2hraquarist.com
				




JPC


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## jaypeecee (22 Mar 2021)

Nick potts said:


> 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


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## dw1305 (23 Mar 2021)

Hi all,


jaypeecee said:


> Does that mean that most people don't grow soft water plants?





jaypeecee said:


> 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


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## Wookii (23 Mar 2021)

jaypeecee said:


> 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:
> 
> ...



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:


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## jaypeecee (23 Mar 2021)

dw1305 said:


> ...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


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## jaypeecee (23 Mar 2021)

Wookii said:


> ...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:






						Using Peat To Lower Water pH
					

Spraying is definitely only done with very soft water, because otherwise the lime blocks the nozzles. 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. But exact...



					www.ukaps.org
				




So, I'm confused.

JPC


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## Wookii (23 Mar 2021)

jaypeecee said:


> 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:
> 
> ...



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


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## jaypeecee (23 Mar 2021)

Wookii said:


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


Would one of the admins - @Tim Harrison and/or @LondonDragon please confirm the above?

JPC


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## Wookii (23 Mar 2021)

jaypeecee said:


> 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:
> 
> ...



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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## jaypeecee (23 Mar 2021)

Wookii said:


> 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.


Hi Gareth (@Wookii)

You are absolutely correct and I chose my words badly. In my head, I was very clear what The 2HR Aquarist was saying. His message was as clear as a bell. Quite how my brain managed to mangle it, I don't know. Well, I do really - but I'm not going there! Anyway, thanks for correcting me.



Wookii said:


> 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 referencing.



You may well be right. I'm just seeking clarification. If @Christel finds time, I look forward to hearing what she has to say.

JPC


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## Nick potts (23 Mar 2021)

jaypeecee said:


> 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.


That is going to be a big list lol.


jaypeecee said:


> 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:
> 
> ...



I don't think that PH is all that important, and lots of sources are going to have different values depending on what they believe.

As Wooki has pointed out, soft water does not necessarily mean low PH, if you take my tap water as an example, it has a TDS of 70 and a KH and GH of 1, this would be classed as very soft, but high PH at >8

I have had no problems with any plants that I could put down to the high PH of my tap water.


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## dw1305 (23 Mar 2021)

Hi all,


Nick potts said:


> as an example, it has a TDS of 70 and a KH and GH of 1, this would be classed as very soft, but high PH.


A lot of people have soft, alkaline water now. This is because of the  addition of sodium hydroxide (NaOH). Sodium hydroxide is a <"strong base">.


jaypeecee said:


> 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"?


Probably those in the <"Tropica Easy"> category. 

cheers Darrel


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## LondonDragon (23 Mar 2021)

jaypeecee said:


> Would one of the admins - @Tim Harrison and/or @LondonDragon please confirm the above?
> 
> JPC


You can put links to anywhere you like as long its relevant and not nasty stuff 
There is always a Report button under each post if the content needs auditing!!


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## jaypeecee (23 Mar 2021)

LondonDragon said:


> You can put links to anywhere you like as long its relevant and not nasty stuff



Hi Paulo (@LondonDragon)

Thanks for confirming that.

JPC


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## jaypeecee (23 Mar 2021)

Wookii said:


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


Hi Gareth (@Wookii)

OK, I got this confirmed by @LondonDragon - thanks, Paulo.

I therefore suggest that you may want to take a look at the following:









						Nerdy chemistry question
					

Do you all know how measure the ph of the substrate? Would you do it like you would soil? Or long syringe and just pull water from the bottom (this seems wrong)?   Sent from my iPhone using Tapatalk  Why? You are measuring free protons not bound.. How is soil pH measured? pH is determined by...




					www.plantedtank.net
				




I wonder who the user, Anon is! Pretty obvious really. 😉

Anyway, please take a look at what is being said. I look forward to yours and anyone else's comments.

JPC


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## jaypeecee (23 Mar 2021)

dw1305 said:


> Probably those in the <"Tropica Easy"> category.


Hi @dw1305 

OK.

JPC


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## rebel (23 Mar 2021)

jaypeecee said:


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


Use gH/kH to measure the water rather than pH. gh 5 and kh 2 would do you nicely.


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## MichaelJ (23 Mar 2021)

dw1305 said:


> Probably those in the <"Tropica Easy"> category.


Being low-tech myself,  the plants in the "easy" category are exclusively the ones I am sticking to - with good success thus far and there are actually a lot of nice options.
I think Tropica mostly categorize plants in the "medium" and "advance" category as being medium to high on especially CO2 demand, but also specific demands on such as water softness - those are rare anyway at LFS in my area at least.

Cheers,
Michael


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## Roland (29 Mar 2021)

When i use HYDRO 0/5 mineralizer keep this one water parameters 
-GH/5
-KH/0-1
-MG/8 
-CA/28
-K/ WITCH IS VERY IMPORTANT! 12/15PPM
-N/VERY LOW
-PO4/VERY LOW
-MICRO FROM AQUA REBELL-FLOW ROW
-ALL ON ACTIVE SUBSTRATE LIKE TROPICA SOIL+TROPICA CAPSULES+SOME SEACHEM MATRIX ON BOTHOM+ CO2+ GOOD LIGHT


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## Wookii (29 Mar 2021)

Roland said:


> When i use HYDRO 0/5 mineralizer keep this one water parameters
> -GH/5
> -KH/0-1
> -MG/8
> ...



What is your water change schedule Roland?


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## Roland (29 Mar 2021)

A minimum of 30 percent every week Wookii


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## Zeus. (29 Mar 2021)

Roland said:


> When i use HYDRO 0/5 mineralizer


Just did a clone for product on IFC Calculator, can be tweaked to suit any tank size


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## Wookii (29 Mar 2021)

Roland said:


> When i use HYDRO 0/5 mineralizer keep this one water parameters
> -GH/5
> -KH/0-1
> -MG/8
> ...



Also when you say 'very low' for N and P, what ppm are you dosing approximately per week? (Sorry to keep asking you questions, but given the exceptional clean and vibrant growth you achieve in your tanks, you have clearly achieved some optimum dosing).


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## Roland (29 Mar 2021)

Ok, no problem, I doses fertilizers every day, except for the day I change the water, but after the water change I have 0ppm N and 0 ppm PO4  in the water, so I dose the fertilizers to get 5ppm / N  0.20ppm po4 and 15ppm k. The next days I dose the fertilizers low. 1/2 PPM N, 0.10ppm po4 and potassium gives 2 ppm in the middle of the week + micro producer dose the same every day. The rest of the fertilizer is given by the active substrate, so I can afford to fertilize low or even very low.A good way is to zero the water, replace 80 percent of the water with water + mineralizer and add NPK. It is then easier to calculate because I have almost 0 NPK in the water.In the event of algae occurrence, resetting the water also gives very good results


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## Christel (8 Apr 2021)

Hi, Sorry for my late response. 
The aim in nurseries is to offer the plants as many nutrients as possible in sufficient quantities - a nutrient solution, so to speak, in which the plants grow with their roots. Each species absorbs the nutrients it needs in a species-specific manner - for example, one species needs more iron than another. Provided that the nutrient solution contains sufficient iron. But a generally high nutrient supply also means a high conductivity, which can be measured. 
One of the most important plant nutrients, however, is carbon dioxide. At an acidic pH, free CO2 is predominantly present. At an alkaline pH, little or no carbon dioxide is present. Most plants stop growing at an alkaline pH. Only a few species can assimilate the hydrogen carbonate ions and get the C, the carbon as an important plant nutrient, from it. This is the main reason why CO2 fertilization is important. Of course, you can also get the carbon into the water by feeding the fish heavily. In nature, most of our aquarium plants live in soft, acidic water! This includes - even if Diana Walstad writes otherwise - almost all Echinodorus species. I have been at so many natural Echinodorus habitats, that I have a very good overview. And I measured always!  Only a very few Echinodorus-species I have found in weakly alkaline water, such as E. uruguayensis. In addition, many plants are adaptable to water chemistry within _certain limits_, but many species are not, e.g. Tonina fluviatilis, which is an indicator plant of very acidic waters at pH values below 6. This plant cannot grow in hard, alkaline water; it is the same with Syngonanthus, many Eriocaulon and other species. But the pH and the carbon as an important plant nutrient is only one aspect of plant nutrition. 
I hope it is clearer now.


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## jaypeecee (8 Apr 2021)

Christel said:


> Most plants stop growing at an alkaline pH. Only a few species can assimilate the hydrogen carbonate ions and get the C, the carbon as an important plant nutrient, from it. This is the main reason why CO2 fertilization is important.


Hi @Christel 

Many thanks for your valued reply.

So, the injection of CO2 has a dual role:

[1] Provide carbon

[2] Acidify the water

Whilst there is much talk about the first of these, there appears to be less emphasis placed on the latter of these two factors. For myself, I've long been aware that CO2 injection lowered pH but only very recently was I beginning to suspect that I may be overlooking something.

Thanks again.

JPC


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## jaypeecee (8 Apr 2021)

Christel said:


> In nature, most of our aquarium plants live in soft, acidic water! This includes - even if Diana Walstad writes otherwise - almost all Echinodorus species.


Hi @Christel 

Thank you for this clarification.

So, we ought to measure tank water pH every day at around midday, for example - regardless of whether or not we are injecting CO2. Would you agree with this and what range of pH values should we aim for?

JPC


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## Saman (9 Apr 2021)

Really pleased I’ve found this thread as I’m interested in this area too. I use 100% RO and remin with JBL aquadur to get a kh of 2 and gh of 4. My ph goes from 6.8 to 7.6 (morning to evening) but I really want to try and keep it in the 6-7 range for the type of fish I keep. I’m considering just using equilibrium for gh and/or putting botanicals in the tank.


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## dw1305 (9 Apr 2021)

Hi all,
Welcome to UKAPS.


Saman said:


> I use 100% RO and remin with JBL aquadur to get a kh of 2 and gh of 4.........and keep it in the 6-7 range for the type of fish I keep


If you want to keep the pH lower you can use a mix that doesn't add any dKH. As soon as you add carbonate buffering the pH will rise to ~pH8, due to the <"carbonate  ~ CO2 ~ pH equilibrium">. 

When you reduce that pH (by adding an acid) all that happens is that bicarbonate ion (HCO3-) buffer is converted to CO2.  The only time this isn't true is when you add CO2, in which case the pH drop is caused by the extra carbonic acid (H2CO3-) which disassociates into a proton ( H+ ion)  and a bicarbonate ion (HCO3-). Acids are defined as <"proton donors"> and the pH drops.

You can really easily DIY a mix (that just gives dGH) from "Epsom Salts" (MgSO4.7H20) and calcium chloride (CaCl2.2H2O).  The workings are at <"James' Planted Tank"> and both salts are widely available via ebay etc.


Saman said:


> I’m considering just using equilibrium for gh and/or putting botanicals in the tank.


Yes, that should work. I'm a great fan of adding some <"humic substances">. You've still got time to pyo your <"own leaves and Alder cones">.


Saman said:


> My ph goes from 6.8 to 7.6 (morning to evening)


Assuming that you don't add CO2? This is just because of changes in the oxygen : CO2 ratio. There is a more complete explanation in <"TDS and remineralising ro water">. You can't really have pH stability in very soft water, it is always going to be <"a movable feast">.

cheers Darrel


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## Saman (9 Apr 2021)

Thank you for explaining - no CO2 in this tank but I’m starting a new tank next week and I’ll be using it then. It will be interesting to see the difference!


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## dw1305 (9 Apr 2021)

Hi all,


Saman said:


> It will be interesting to see the difference!


I'm not personally a CO2 user, but what should happen is that the pH should remain at the level that gives you a one unit pH drop (~30 ppm CO2) throughout the photoperiod, even though the water will be saturated with dissolved oxygen at the end of the photo-period.

You might be interested in <"Canford Park">, not exactly an aquarium, but an example of the effect of dissolved gases on pH.

cheers Darrel


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## Saman (9 Apr 2021)

Thank you - I’ll have a read


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## Christel (9 Apr 2021)

jaypeecee said:


> Hi @Christel
> 
> Thank you for this clarification.
> 
> ...


Hi, I would aim for a pH between 6.4 and 7.2 in an aquarium with many fish. This fits with most fish and most aquarium plants. If you want to cultivate special plants, like some Eriocaulon species, you have to lower the pH even further - but that doesn't work with all fish. Such plants should be maintained in a special aquarium. We also have to consider the health of the fish in our aquarium. 

In the beginning it makes sense to measure the pH in the morning, at noon and in the evening. In the evening it is higher because the plants have used CO2. I don't have a night cut-off, because in the morning the pH is not in the dangerous range for the fish. As soon as a stable environment has settled down, you don't need to measure the pH value so often. By the way, good plant growth can be seen in the assimilation of the plants! It is important to observe the plants well - at some point measuring is no longer important, but you can see the plants and the fish whether everything is good or you have to intervene. Christel


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## dw1305 (10 Apr 2021)

Hi all,


Christel said:


> By the way, good plant growth can be seen in the assimilation of the plants! It is important to observe the plants well - at some point measuring is no longer important, but you can see the plants and the fish whether everything is good or you have to intervene.


That is the <"approach I recommend as well">. Put at its simplest level "_the plants (or fish) can't lie_".

It doesn't sounds as "scientific" as doing lots of water tests etc., but it is an entirely <"valid scientific method"> and really just <"a form of bioassay">.  I'd like to be able to <"quantify exactly the processes"> that were occurring in the tank, but there are a lot of variables and "_watch the plants_" works.

cheers Darrel


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## Saman (11 Apr 2021)

I’m just starting with equilibrium to lower the ph but I’m wondering once the kh is 0 how do I stop the ph dropping too far? Will my tank provide natural buffers? I have some rocks in there. I have soft water fish - threadfins and chilli rasboras - but I don’t want to drop lower than 6. Thank you


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## dw1305 (11 Apr 2021)

Hi all,


Saman said:


> once the kh is 0 how do I stop the ph dropping too far? Will my tank provide natural buffers? .......... but I don’t want to drop lower than 6.


The tank will buffer itself to some degree, but you don't need to <"worry about the pH dropping">.

The issue is <"with the pH scale">, rather than the water. Buffering and pH are conceptually difficult and most of what you read is based upon a premise that we know isn't true.  Nitrification is compromised in soft water, but to nothing like the level that was assumed before we knew <"which microbes were actually involved in nitrification">.

One reason that "blackwater" fish are difficult to keep is that they have evolved in soft, acidic, tannin stained water where all microbial activity is much reduced. When you keep them at higher pH levels they often succumb to bacterial infections.

You can't <"extrapolate from hard water to soft water">, in hard water it takes big changes in water chemistry (ionic constitution) to cause small changes in pH and in soft water large changes in pH are caused by <"small changes in water chemistry">. The way I get around this is to ignore pH and just look at changes in water chemistry, via measurement of conductivity.

Even though I'm not a CO2 user, it was hearing about CO2 injection that made me interested in <"pH stability as a concept">.  Once you know that aquascapers have healthy fish, but their tanks go through a cycle of a drop of one pH unit, and subsequently a rapid rise of one pH unit, every day you know that it isn't pH change, as such, that is the problem.

cheers Darrel


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## Saman (11 Apr 2021)

Thanks Darrel- this is really fascinating. I guess my main worry is once I remove kh the ph will swing all over the place. After everything you have shared I’m not worried about a unit of fluctuation anymore but I’d like to drop it down a level of fluctuation but no more than that. I will use equilibrium and observe what happens - I can always add the kh back in. Another plan could be to keep the kh at 1 and see what the botanicals do - maybe that’s a good mid way. Thanks again for your help. I’ll read your links.


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## jaypeecee (11 Apr 2021)

Christel said:


> Hi, I would aim for a pH between 6.4 and 7.2 in an aquarium with many fish. This fits with most fish and most aquarium plants. If you want to cultivate special plants, like some Eriocaulon species, you have to lower the pH even further - but that doesn't work with all fish.


Hi @Christel 

Thanks very much for your reply, which is _very_ helpful - particularly the pH figures immediately above. I tend to prefer the soft water, lower pH fish anyway - Cardinal Tetra, Rummy-Nose Tetra, German Blue Rams, Otocinclus, etc.

JPC


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## sparkyweasel (11 Apr 2021)

Saman said:


> starting with equilibrium to lower the ph


Seachem Equilibrium?
I don't think that affects pH.


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## MichaelJ (11 Apr 2021)

sparkyweasel said:


> Seachem Equilibrium?
> I don't think that affects pH.


Right. It won't. I have never seen it happen anyway.
Seachem - Equilibrium


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## Saman (12 Apr 2021)

The idea of using seachem equilibrium with RO is that it targets gh and not kh. So with 0 kh the ph can drop. At least that’s what I understand from reading this thread and others. I did a w/c yesterday with RO with just seachem equilibrium and the ph has indeed dropped from 6.8 to 6.6 (just tested before lights on) and I’ll see what happens as the day goes on.


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## MichaelJ (12 Apr 2021)

Saman said:


> The idea of using seachem equilibrium with RO is that it targets gh and not kh. So with 0 kh the ph can drop. At least that’s what I understand from reading this thread and others. I did a w/c yesterday with RO with just seachem equilibrium and the ph has indeed dropped from 6.8 to 6.6 (just tested before lights on) and I’ll see what happens as the day goes on.


Yes supposed to be GH only.... but Interesting observation.  Whats your tank KH ? With very low KH and specific tank conditions, I wonder if the pH would have dropped regardless of the equilibrium.


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## Saman (12 Apr 2021)

The kh has been at 2 for a while and the ph starts at 6.8 just before lights on then rises to 7.6 before lights out. With the 50% w/c yesterday with just equilibrium the kh is now 1ish and the ph dropped to 6.6 before lights on. At midday it was 6.8 so definitely lower. The gh has dropped to 3 which I didn’t mean to do - need to work out the right dose of equilibrium to keep it at 4. I think I’ll need to add botanicals to hit the 6.4 mark but we’ll see.


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## jaypeecee (19 Apr 2021)

dw1305 said:


> Once you know that aquascapers have healthy fish, but their tanks go through a cycle of a drop of one pH unit, and subsequently a rapid rise of one pH unit, every day you know that it isn't pH change, as such, that is the problem.


Hi Darrel (@dw1305) & Everyone

I think you will all find that the following study supports what is being said here in the preceding posts. And, note the date of the document below - almost exactly 17 years ago...



			https://www.waterboards.ca.gov/rwqcb5/water_issues/basin_plans/ph_turbidity/ph_turbidity_04phreq.pdf
		


Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting. Please shout if you think otherwise!

JPC


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## dw1305 (19 Apr 2021)

Hi all, 


jaypeecee said:


> I think you will all find that the following study supports what is being said here in the preceding posts.............Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting.


It does, pretty much, says the same thing and there isn't any reason why it shouldn't be equally applicable to both ponds and streams and aquariums.


> ..........The pH of lakes and streams often changes during the day in response to photosynthetic activity. In ponds having poorly buffered (low alkalinity) waters, the pH may fall to approximately 7 in the early morning and increase to 9 or more in the afternoon (Boyd 1990). Good fish production usually can be maintained in spite of these daily fluctuations. In most lakes and ponds, diurnal pH fluctuations during the summer, when photosynthetic activity peaks, are generally less than 2 pH units, while in streams are generally less (e.g., 0.5-1.0 units). Unless diurnal fluctuations result in ambient pH falling below 6 or being elevated above 9, they generally have no adverse impact on aquatic life. This is supported by the study findings discussed below...............


Reading through it I think it might not be entirely objective and they may have had an agenda, possibly to do with trying to deflect complaints about the acidification of certain water sheds?

cheers Darrel


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## jaypeecee (19 Apr 2021)

Hi Folks,

Please refer to the study that I mentioned above in post #55.



jaypeecee said:


> Although the above study was carried out on surface waters, I can see no reason why the findings of the study shouldn't apply to ornamental fish and other livestock in an aquarium setting.



On reading the study again, I see that the aquarium setting and freshwater tropical fish do in fact get a mention on page 6 in the second paragraph.

JPC


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