# Killies Import > Planted Tanks >  PH problem

## cminghan

how to decrease PH but wont affect KH.

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## whuntley

Hi Ming Han,

Adding weak acids will reduce pH. I'm not sure why anyone would ever want to do this, for plants and fish don't much care what the pH is in normal ranges.

If you have an ammonium/ammonia problem, you can reduce the toxicity by lowering pH, but that is no solution. Solve the ammonium problem by other means.

I guess we need more information to know what you wish to do. 

The way a buffer system like carbonate/bicarbonate works is to take up the extra hydrogens from a weak acid to slow the rate at which pH is lowered.

CaCO3 <-> CaHCO2

Wright

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## imported_bpt

> how to decrease PH but wont affect KH.


Ming Han, if its planted tank, use of CO2 will decrease PH and be beneficial for the plant.

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## cminghan

for me, i will use peat to decrease the water ph, just put in for 2 days then i will take it out, because this peat from fluval and go until 4 ph, why i need to decrease the ph because my area the tap water was about 7.8-8ph. so when my ph go down, same apply to my kh....so for me to increase kh again, i will use KH+ powder, but this will affect my ph.with this powder i can get the kh that i want, but the ph was run off from the parameter that i need.
today i just try this....i put in the KH+ to increase the KH, but i get high ph,to reduce ph without affecting the KH, i used some RO water with viniger.seem like it work...my ph now goto 6.5 and 5kh, no sign of sickness over the fishes and plant at the moment....
any one have any more ideas.

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## stormhawk

Minghan, if you're using apple cider vinegar then its no problem. However, you shouldn't use the standard clear vinegar. 

You can use peat like you said to lower the pH but since your kH powder somehow reduces that low pH effect, all you need to do is to find a replacement for the kH powder. Try a small pack of coral chips and some peat alongside. That is just a suggestion so good luck if it works.  :Wink:

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## cminghan

i tried coral chip before, same like KH+ powder. when ever i dip them in the water the KH will go up..same happen to the PH too. 
i am using those LEE KAM KEE white vineger, as i read from the ingredient, it said acid water with caremel.so far, i haven't see any sick fishes yet.
i seldom do this kind of KH increase. its because ii have introduce the tonina to my tank. i have 2 types of tonina, one is the very fine leaf anotehr one is abit bigger the leaf, the fine leaf one was turning yellowish. so after i do some reseach it said they need strong lighting, high co2, lower ph and abit of KH.
because of the sudden adjustment. i just introduce one downoi and one bulloso into the tank..i am not so sure can they survive in this or not.
anyway thank for all your help.

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## stormhawk

Well for starters you should try to keep plants that have similar requirements, rather than to keep one that requires some sort of special care. It makes life a whole lot easier.

Some people I know, use baking soda to increase KH. For such cases one should always err on the side of caution. With your KH powder, have you tried reducing the dosage that you use? A reduced dosage may help in preventing the pH from rising too high too quickly.

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## stormhawk

Another thing, I don't think you understood what I meant. What I was saying is, to use both peat and the coral chips at the SAME time. It works for me on certain occasions. Try that and see how it goes. Use a test tank to see if it works for you.

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## PohSan

Hi Ming Han,

May I know if both of your "Cap lock" and "Shift" keys of the keyboard missing or what??

Regards,
Ong Poh San

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## cminghan

i dont think that is nessesary, if every single thing is so taking care of...its very limiting the forumer to do what they want. i dont know why we are not allow to use short form and etc. i felt very unconfortable with that.
beside, as long as i can send my message, people get to know what i want and give me feedback, and others read this and they can understand.i think this is good enought. i am sorry if this make you unhappy.

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## RonWill

Ming Han,
A home has house rules and so does this forum. While it is not an absolute comliance to using the shift keys, it is a common courtesy that you are extending to fellow forumers here.

You may not be aware of this but some of us are dyslexic; which means we have a hard time reading a post that is filled with SMS lingo, sentences lumped together (no paragraph breaks), all capatilized or in your postings, all in lower case.

It would make me, plus a few others very happy, if you can make reading much more enjoyable.

[Poh San was just pointing out something you might have overlooked and believe me, it's nothing personal. Let's just all work towards a better forum. Thank you]

To get back on-topic about lowering the pH, I use filter peat granules or if aesthetics was a concern, I'd use ADA soil. Both will stabilize between pH5.5~6.2 over time. [Peat from Sera and Aquarium Munster are easier to handle while the ADA soil crumbles after extended use]

I tried cider vinegar (for vinegar eel cultures) but the parameters were not stable over a week. Being less versed with Chemistry, I'm hesitant to add more chemicals than I need to.

Keeping things simple, I use Merck's broad-range pH test strips for all my readings.

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## FC

Ming Han,

Welcome to the forum!

Poh San really meant to keep up the forum quality here. There are many things made the forums here special (not for unique seek). One of the distintive one being: We wish to keep certain level of quality here because many regional forums had just detriorated/reduced to sms writing, personal conversations, throwing topic of out line as they wish, etc. You will realise right from the door way that we are different and for good reasons - maintaining respect to readers, cultivating the right netiquette, go back to where things (normal writings) had started.

In the beginning, we have many concerns on how new forums feel about such "tight" rule. We are aware some will feel offended, some may feel being too former here, some may be discouraged to write/participate in the forum, etc. However, over time, we concluded that this is the way a forum should be run and maintained. We are not into money making here (purely non-commercial here), we are here to serve the hobbyists as we are hobbyists ourselve. We want fun too, we loved fun and like to relax, be casual but equally important to us is the long term relationship among the forumers.

Be patient with us, I hope you will like our style and appreciate our objectives. It's our job to keep everyone happy here and hopefully for a long long time.

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## PohSan

Hi Ming Han,

I apologise to you if my words sound to harsh to you. But I guess you will not like it also when someone is asking you question in a very rude manner. In fact, your first post of this thread was rude in my own opinion but Wright was kind enough to answer you. What Ronnie and Freddy said is actually what is in my mind. 

Let not be too off the topic. I hope that you are not offended and enjoy this forum as much as I do. Thanks.

Regards,
Ong Poh San

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## cminghan

Ok, let's forget about it. By the way, i checked my PH level again last night. The vineger was useless, the ph level go back to the same level, so i have to force to use peat, and the PH go down, the KH too, now PH is about 7 and 2 KH.
I took the peat out this morning and increased the Co2, how i will get lower PH to night. by the way. Thank you so much for those who give me a hand.

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## whuntley

Hi Ming Han,

Pardon me for being so confused, but I fail to understand what you want or why.

Why are you trying to change the pH?

A KH of 2 is a bit low, but only if you are facing a potential pH crash. If not, so what?

Something significant is being assumed in this thread, and I cannot figure out what it is. I hope you can enlighten me, and if you do, I hope I can help.

Wright

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## cminghan

Due to i have some tonina inside. From my reseach they need low ph and abit high kh.
Some how i have give up to keep this tonina anyway.just let it be.
Concentrate on the bulloso and downoi.All the plants in the tank was doing very well but only the tonina give me so much problem.

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## fabry

Hi Ming Han.

First of all let me say that the problem you have (think to have) is inexistent.

The relations between kH, CO2 and pH in water are given by chemical laws that are consistent in every environment on our planet (streams, lakes, sea, your and every aquarium).
In natural habitats soft water has a natural  chemical tendency to be acidic and harder water has a tendency to be more alkaline.
Unless exceptional (and extremely rare and localized) situations are present you will never find in nature a low pH associated with a high kH and vice-versa.
These exceptions can be totally disregarded by water-gardeners and their tanks can be set up consequently.
Tonina too lives in environments that obey these chemical laws so, if your main goal is cultivating aquatic plants (including Tonina), you just have to know the needs of your plants in their natural habitat (e.g. where they come from) and behave consequently with the water in your tank.
All the plants you can be willing to keep in your tank can be handily divided into two categories regarding water parameters:
1) Plants coming from soft (and therefore acidic) water.
2) All the others.

In my experience the problems that plants coming from soft water have in harder water are mainly a problem of inefficient assimilation of iron that can usually be overcome by using the correct fertilizers.
Tonina is one of the plants coming from soft AND acidic water and if you want to cultivate it easily you need to give it what it finds in its biotope: soft AND acidic water. 

Said that I must point out that if you want (and believe me you do not need) to achieve water parameters that are in contrast to natural water chemistry (for example low pH and high kH) the ONLY way is to manipulate the laws that regulate the relations between pH, CO2 and kH.
These relations correlate carbonates, Carbonic acid-CO2 and H+ ions (and OH- ions consequently).
I do not want to write a paper on water chemistry here, so I just tell you that the only way you have to interfere with these relations is to provide, from an external source, a chemical that is part of the reaction or take away from the water one chemical that is part of it.
In your case the only practical thing you can do if supply Carbon Dioxide (CO2).

If you pour in your tank an acid which is not Carbonic acid (and stronger than it) you will displace the carbonic acid present from its salts, thus producing CO2, lowering pH but ALSO lowering kH. 
This is what happens when you introduce acetic acid (vinegar) or humic  fulvic acids (peat).
For example starting from calcium bicarbonate (kH) if you add vinegar (acetic acid) you will finish having CO2 and Calcium acetate at the expenses of Calcium bicarbonate. 

If you later want to try to increase kH by adding salts (bicarbonates) the pH will increase again consequently.
There is nothing you can do about it unless you add continuously Carbonic Acid (CO2).
Thats the way nature and its chemical laws work. 
Once again plants that like a low pH like also a low kH because that is what they find in their natural habitats.

Nature and water-gardening are not as complicate as we usually imagine.

Let me know if the above is O.K. to you or something sounds strange, but please consider that this matter should require a short treatise and its very difficult to explain it in few words and without some chemical equations.

Best regards.

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## RonWill

> In natural habitats soft water has a natural  chemical tendency to be acidic and harder water has a tendency to be more alkaline


 Hi Fabrizio, could you elaborate further (in layman's term, please) why this is so. Is there no natural occurence where water is both acidic and hard?

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## FC

Dear Ming Han,

Thank you for using the "Shift" key.

Contrary to what you found, Tonina needs acidic and soft water (like what Fabrizio mentioned). For that, the water source is also typically low in KH too. And that is consistent with my experience with Tonina.

Try not to add anything but instead remove them; use RO water. First check your water parameters and at least for GH, KH, PH. I guess you have hard water with GH in the region of 8 degree and KH of above 4. Then, use CO2 (only) to bring down the PH, level depending on CO2 concentration you need and KH you have.

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## cminghan

My PH level was 6-6.5 now but the KH now drop to 0, I never test my GH. 
Is GH important in planted tank, how can i increase them and decrease them?

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## FC

You should check the tap water, not the tank's water. Your tank's water require "reset" or large water change.

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## fabry

> Hi Fabrizio, could you elaborate further (in layman's term, please) why this is so. Is there no natural occurence where water is both acidic and hard?





> My PH level was 6-6.5 now but the KH now drop to 0,


Hi Ronnie and Ming Han.
Just a little preface that could help someone before answering your question.

Carbonate hardness (would be better to call it Alkalinity or water buffer capacity) is a part of a buffer system including Carbonic Acid (from CO2) and some of its salts (like Calcium/Potassium/Sodium/Magnesium Bicarbonate).

This buffer has the capability to contrast ph fluctuations.

To explain how this happens, let us consider the following example in which we add some Hydrochloric acid to a solution of Sodium Bicarbonate.
Putting it in a simplistic way we could say that:

NaHCO3 + HCl = > NaCl + H2CO3 => NaCl + H2O + CO2.

Which means that the Hydrochloric acid, stronger than the Carbonic one, displaces the latter from its salt.
Carbonic acid has then the tendency to break up into water and CO2.
CO2 is taken up by plants thus remaining NaCl + H2O.

As you can see no trace has remained of the H+ ions we added (the acid) AND of the bicarbonates originally present into the water. 

Therefore we can add acids (ions H+) until we have bicarbonates (NaHCO3 in this example) without affecting the pH and producing the only effect to decrease alkalinity (KH).

If we continue to add acids sooner or later the bicarbonates/carbonates will disappear and the H+ ions of the acid will remain free into the water thus causing the pH to collapse (possibly killing plants an fishes).

Thus soft water (low Alkalinity/buffer capacity) is easier than hard water to have fluctuations of pH if some sources of H+ (or OH+) are available.
Generally in nature we have sources of H+ ions (acids coming from decomposition of organic matter  carbonic or fulvic for example).
The most present in the waters we need to consider is by far Carbonic Acid (CO2).

CO2 content in a stream/lake is mainly dependent on the amount of organic matter that decomposes in it, so we can consider first that it is a given value (pretty stable and dependent on exogenous variables) and take a look at the table in the link below (sorry for the poor quality): 



As you can see, given the concentration of CO2, the pH depends on water alkalinity.
For example if we have 30 mg/l of CO2 the pH can be 6.6 at a KH of 4, 6.4 at a KH of 2.5 or even 6.0 at a KH of 1.

Hence softer waters have also a lower pH in comparison to harder waters that have also a higher pH.

Of course if someone dumps in the water some amounts of organic matter this will be decomposed by bacteria producing CO2 and lowering the pH (again considering the same KH) even further.
So, one of the very few possibility to see a water with high Alkalinity (KH) and low pH is to have a source of CO2-Carbonic acid into the water (thermal, decomposition or whatever).
Acids other then carbonic, like the humic-fulvic acids coming from peat and humus will lower the pH too, but will also lower KH accordingly. 

All this means two things for aquarium-keepers:

1) There is no need nor utility to go against nature trying to have a low 
pH with a high KH in our tanks.
2) Trying to decrease pH with acids different from Carbonic acid (CO2) 
without affecting (decreasing) consequently also KH is totally hopeless.

Hope this helped Ming Han and someone else.

Regards

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