# Getting from straight R/O to healthy aquarium water



## bk. (Sep 27, 2014)

I use equilibrium and the alkaline buffer. I add the buffer until my ph tests at 7.0. Then I use co2 to get a 1.0 drop, down to a pH of 6.0. 

How low are you looking to go with pH? The pH of straight RO for me is well below the neutral, 7.0. I believe I'm in the 4-6 dKh rating after adding enough of the alkaline buffer to get the water up to 7.0.


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## plantbrain (Dec 15, 2003)

Most folks just blend tap with the RO to get a specific KH. 

Say the tap is 10 and the RO is close to 0, then you blend say 25% tap with 75% RO for the water change.
KH is now 2.5.

Saves a lot of RO water that way.


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## end3r.P (Aug 31, 2015)

plantbrain said:


> Most folks just blend tap with the RO to get a specific KH.
> 
> 
> 
> ...



Thanks Tom. I can't use tap unfortunately, because it all goes through a water softener (even outside spigots) I've consistently read that's not good for plants or fish, and the water post-softener reads as 0 degrees KH anyway. So I'm stuck with adding back minerals and buffers to straight RO, and trying to find a way to do it that will result in a stable pH that is acidic or at least not much over 7. Seachem Equilibrium and Acid/Neutral Regulators seem like the best options for that so far... Unless I'm just wrong about the dangers of 0 degree KH.


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## Argus (May 22, 2013)

I was using half RO and half tap water, but became a little concerned about what dissolved metals might be in the tap water. So, I've been experimenting with re-mineralizing RO water with 



 for GH and 



 for KH. It has been working well.


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## end3r.P (Aug 31, 2015)

Argus said:


> I was using half RO and half tap water, but became a little concerned about what dissolved metals might be in the tap water. So, I've been experimenting with re-mineralizing RO water with Seachem Equilibrium for GH and potassium bicarbonate for KH. It has been working well.



How much potassium bicarbonate, and what pH range does it give you?


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## Audionut (Apr 24, 2015)

1.4 grams per 10 gallons will yield an increase of 1 dKH. This will also add 14ppm of potassium.

All carbonate sources will want to buffer at a pH above 7.0. You need to have carbonate sources to maintain balance, so to offset the carbonate effect on pH, and lower pH, the solution is to add acid sources to compensate, were the balance of acid and alkaline give you the desired pH.


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## Argus (May 22, 2013)

end3r.P said:


> How much potassium bicarbonate, and what pH range does it give you?


About 5 min. almost empties my RO reservoir. That is somewhere around 1.25-1.5 gal. I think. To that I add 1/2 tsp. of potassium bicarbonate and 1 tsp. of Equilibrium. Then I test GH and KH to make sure they are both about 5 dkh and TDS is close to the tank value. I don't bother with pH. 

I made the mistake of trying to control pH with chemicals (pH Down) and just stressed the fish. Lost some corys and otos that way.


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## Linwood (Jun 19, 2014)

In general, you will find it is easier to maintain stability if you don't try to add acid to "fix" the PH from adding alkalinity. Yes, there are "acid buffers" you can add, but the natural (as in what you see in nature generally) approach is that the dKH determines the PH. The aquarium will reach equilibrium with air's CO2 (usually around 3ppm), and this be controlled by the dKH. Near zero dKH in RODI water and you get very acidic water (like 5.5 +/-, and no pure water in an open top tank is not at ph=7). As you get near dKH=1 or so you get near ph=7, and as it increases you get higher and higher PH.

If you are going for near neutral, just experiment a bit starting at about dKH=1 and see where you land (it will vary based on your situation, aeration, take contents). Add a bit more baking soda to get a bit higher, withhold (but don't withhold it all) to get lower PH. I've also found Equlibrium adds dKH as well, even though it is not supposed to, so getting high dGH and low dKH is not easy.

Yes, you can add acids to lower the ph, but all tend to have some side effect, from being temporary to changing the chemistry otherwise. 

Incidentally, good old baking soda which you can buy by the 5 pounds for a few bucks is just fine for alkalinity. There's a ton of potassium already in Equilibrium.


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## Diana (Jan 14, 2010)

Here is how I do this:

1) Set the GH to suit the fish. (Seachem Equilibrium), most soft water fish, about 3 degrees. 
2) Make the KH match the GH. (Baking soda: 1 teaspoon per 30 gallons = 2 German degrees of hardness) or potassium bicarbonate as above. 
3) For black water fish circulate the water with peat moss (Knee-hi stocking per garbage can of water. 'Garbage can' could be 20-40 gallons- I have several)


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## Linwood (Jun 19, 2014)

PS. A typical mix for me for 10 gallons is 0.18 tsp Baking Soda (i.e. a quarter tsp measure a bit over half full, very little), and 1.5tsp of Equilibrium. This should be dKH=1 but seems to land about 2+, and a dGH of about 3, and PH in the 7.2-7.4 range. This is in RODI water. You're saying RO water, which may already have stuff in it if you mean it literally.


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## Diana (Jan 14, 2010)

The pH is less important to the fish than the mineral levels. 
Get the GH and KH right, and don't worry about the pH. When GH and KH are in the right range, the pH will likely be in the right range, too.


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## Audionut (Apr 24, 2015)

Linwood said:


> Yes, you can add acids to lower the ph, but all tend to have some side effect, from being temporary to changing the chemistry otherwise. .


Carbonates can (and) do the exact same thing. 

The only difference between carbonate buffers and acid buffers (apart from the obvious effects on pH) is the level of knowledge parroted through the industry.


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## end3r.P (Aug 31, 2015)

The main thing I don't understand is that many if not all solutions to stabilizing pH at neutral or acidic levels with low/no-KH source water include adding both an alkaline buffer (baking soda, Seachem Alkaline Buffer, etc.) AND what amounts to an acid buffer (peat, Indian almond leaves, Seachem Acid Buffer/Regulator, etc.). To my not-chemist brain, it seems like these would just cancel each other out, leaving you with still-unbuffered water subject to big pH swings. But I'm thinking that's not true, i.e., that you can add both, and each will buffer against pH swings in the opposite direction (alkaline buffers protect against pH drops, acid buffers protect against pH increases), and that the resulting pH is (at least in part) a function of the proportions of the two buffers used. Put another way, when you add an acid buffer (as opposed to, say, straight acid?) it drops pH some, but doesn't "eat away" the alkaline buffer, at least not entirely. So you can have an acidic or neutral pH with a low but non-zero alkalinity/KH. Maybe.

The science behind any of this, of course, is mud to me right now.


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## Audionut (Apr 24, 2015)

There is an equilibrium point between acid and alkaline buffers. This equilibrium point determines the pH.

What pH doesn't describe is the amount of buffers in the water. We can reach the same equilibrium point (the same pH), with a little acid buffer and a little alkaline buffer. We can also reach the same equilibrium point with lots of acid buffer, and lots of alkaline buffer.

The equilibrium point (pH) is like a ratio. You can have the same ratio with vastly different amounts of total content. One banana, and one orange have a ratio of one banana to one orange, or 50/50. Three trillion bananas and three trillion oranges have the same 50/50 ratio.

Acid buffers will deplete alkaline buffers, but you need to understand the above first.


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## Linwood (Jun 19, 2014)

Audionut said:


> Carbonates can (and) do the exact same thing.
> 
> The only difference between carbonate buffers and acid buffers (apart from the obvious effects on pH) is the level of knowledge parroted through the industry.


Well, "exact" is a bit of a push, though I take your meaning. The problem is that the "natural" sources of alkalinity are very well behaved and readily available (e.g. baking soda). The natural sources of additional acidity often tend to be organic (e.g. rotting leaves), and what you get in a bottle in the store are often poor mimics. In some cases downright bad ideas, like mineral acids.

In a _loose_ sense you can think of the balancing act similar to a scale, you add alkaline to offset the acid coming from CO2. On a scale, you could also add more weight to each side (more acid and more alkalinity) and achieve a similar balance. 

But every thing you add to your aquarium tends to have side effects, and what comes in bottles as a "quick fix" rarely is the best solution, and often is a downright scheme to get you to keep using more and more of it.

I'm a big fan of minimal intervention. The less "stuff" you try to add, the less side effects from whatever you were trying to fix. PH, as has been pointed out, is rarely even the problem. Managing GH and KH to an comfortable point for your will yield a PH your fish will be quite happy with, almost by definition, as that is what happens in nature.

I do not suggest that such mild and continual treatments such as peat are bad. I do suggest that a lot of the fixes-in-a-bottle to lower PH are more harm than good.

And as one data point, when I stopped using Seachem's Acid Buffer (one of the more reputable companies IMO) and instead just used Alkalinity Buffer, I found my water was much more stable over time and water changes.

Incidentally, lots of good info at this site, and links to others: 

Acidity/alkalinity: what is the pH of your water? | The Skeptical Aquarist


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## Oso Polar (Apr 22, 2015)

Audionut said:


> The equilibrium point (pH) is like a ratio. You can have the same ratio with vastly different amounts of total content. One banana, and one orange have a ratio of one banana to one orange, or 50/50. Three trillion bananas and three trillion oranges have the same 50/50 ratio.


Well, this is clear. This example also very clearly demonstrates the concept of buffering - if you have big buffering capacity then it is much more difficult to change pH: add one banana to your first example, and ratio suddenly becomes 2:1, add one banana in the second case, and it is still 1:1. :smile2:

However, what is not clear, is how to achieve a *stable low pH*. Everybody says that to achieve pH stability one must use carbonate buffers, usually potassium or sodium bicarbonate. This produces a stable pH, but, unfortunately, a *stable high pH*. So, the question is, what can be used instead to achieve a stable but low pH? Say, 6.0? Or 5.5? If nothing is used for buffering in RO water then pH will be low indeed but it'll probably not be stable at all?


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## Linwood (Jun 19, 2014)

Oso Polar said:


> Well, this is clear. This example also very clearly demonstrates the concept of buffering - if you have big buffering capacity then it is much more difficult to change pH: add one banana to your first example, and ratio suddenly becomes 2:1, add one banana in the second case, and it is still 1:1. :smile2:


But don't take the analogy at face value. Bear in mind that it doesn't quite work that simply as there's another side to each component. Water chemistry is about ions, and chemicals in water separate into two "halves" when forming ions. This balance being discussed focuses primarily on one half of each ion, and often omits discussion of the effect of the other half.

To make the analogy a bit more clear, consider that for each banana you bring, you must bring along one big banana leaf. And for each Orange you bring, you must bring along a branch on which it grew. As you reach equilibrium, these leafs and branches are largely ignored, and discarded along the wayside.

If you are offsetting one or two oranges with one or two bananas, this makes for negligible trash. If you have millions, you may still get a balance, but you get a lot of other trash piling up that you might not want.

PH management discussions always focus on just the one side, adding or offsetting the H+ ion (which is natural since PH is by definition the H+ excess). And indeed, you can achieve any balance you want by adding as much as you like (within reason) to each side of the equation. You just need to be aware you are bringing other "stuff" into the mix -- what stuff exactly depends on what bottle you buy.



Oso Polar said:


> However, what is not clear, is how to achieve a *stable low pH*. .... So, the question is, what can be used instead to achieve a stable but low pH? Say, 6.0? Or 5.5? If nothing is used for buffering in RO water then pH will be low indeed but it'll probably not be stable at all?


I do not aim so low so I cannot tell you first hand, but most people i talk to who are not high tech use a continually fed organic, something like peat or leaves.

But bear in mind you can get easily close to neutral with a bit of alkaline buffer. RODI is naturally 7.0 ONLY IF NOT IN CONTACT WITH AIR. As soon as you reach equilibrium by exposure to air it is in the 5.5 range +/-, and you can add some alkalinity back for stability to get back near 7.0.

Now if you have fish that need 5.5.... I have no idea. PH controller I assume, but I don't live in that realm.


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## end3r.P (Aug 31, 2015)

Linwood said:


> But bear in mind you can get easily close to neutral with a bit of alkaline buffer. RODI is naturally 7.0 ONLY IF NOT IN CONTACT WITH AIR. As soon as you reach equilibrium by exposure to air it is in the 5.5 range +/-, and you can add some alkalinity back for stability to get back near 7.0.


This is true, and I generally am in full agreement that the less stuff added to water, the better. I wonder, though, whether RO water with just a little bit of alkaline buffer only, i.e., just enough to get to around 7, will be buffered enough against significant pH swings from decaying organics, plant transpiration/respiration, etc. I'm pretty sure the KH of such water would be around 1 degree.


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## Linwood (Jun 19, 2014)

end3r.P said:


> This is true, and I generally am in full agreement that the less stuff added to water, the better. I wonder, though, whether RO water with just a little bit of alkaline buffer only, i.e., just enough to get to around 7, will be buffered enough against significant pH swings from decaying organics, plant transpiration/respiration, etc. I'm pretty sure the KH of such water would be around 1 degree.


It's a fair question, though of course most of what you mention will lower the ph and you could buffer a bit more and hold PH.

But I do not work at the low PH range, so someone else will be better to answer.

My sole purpose was to caution against some of the commercial goals - remember they are in the business of getting you to use as much of their product as practical.


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## Audionut (Apr 24, 2015)

All good points @Linwood.

You describe some points about cation/anion balance, which is well advised, however most of the issues with cation/anion balance in the manner as you have presented them (excess stuff), is really only an issue when using unnatural sources.

In the carbonate buffer system, the _natural sources_ of buffering are Calcium(Magnesium) Carbonate, and H+ (people neglect the role the H+ ion performs in buffering, but I'll get to that in a minute). Neither of these things could be considered as waste, or excess, in all but specific extreme cases. CaCO3 actually has an excellent ability to bind some of these excess things you describe. When the cation (Ca (Calcium)) and anion (CO3 (carbonate)) bond of CaCO3 is broken, Calcium will then bond with any free anions, forming things like CaSO4, CaCl2. Carbonate will bond with free H+ ions, forming HCO3 (bicarbonate) and H2CO3 (carbonic acid). Of course, these are not one way streets, CO3 can shed these H+ ions to convert H2CO3 to HCO3, and HCO3 to Ca/MgCO3. Cations and anions are constantly bonding and breaking in the cycle of life, and can even precipitate (form an undissolved solid), although with calcium and carbonate, my understanding is that this doesn't happen at the pH of freshwater aquariums.

So yes, when adding unnatural sources, there are bound to be an excess of things that aren't being used at the rate of addition. But with natural sources probably not so much, or at the very least, the excess amounts won't be an issue unless there is some amount of neglect. With neglect being an issue in all cases, regardless of what's being added.


*Buffering at low pH: Aka, the H+ ion.

*Probably the biggest issue with H+ in our closed loop aquariums, is simply that H+ is a weak buffer, _and_ that it buffers at a pH that is not optimal in most circumstances. H+ will readily bond and break with many things, meaning that it is not stable. H+ will very easily bond with CO3 to form the different states, H2CO3 and HCO3, with each of these states resulting in a different balance of the ions, a different equilibrium, and hence a different pH.

But make no mistake, H+ is a buffer. Add enough H+ ions to convert all of the CO3 to H2CO3, and the water will effectively be buffered at a low pH. 

The other issue with H+ as a buffer, is that when it forms H2CO3 (carbonic acid), only a small percentage of this carbonic acid remains, with the majority reacting with the water itself to form CO2. Since Henry's law states that gases in a solution (water) will always try to reach equilibrium with the atmosphere, as H2CO3 concentration increases, a portion of this carbonic acid is thus converted back into HCO3 as CO2 is released into the atmosphere. This means that it is somewhat hard to build up an excess amount of H2CO3.

Allow me to sidetrack for a moment.

Bicarbonate (HCO3) is also a weak buffer. It can readily and easily gain a H+ ion to form carbonic acid (H*2*CO3), or lose it's H+ ion to form carbonate (CO3). Bicarbonates usefulness in aquariums is simply thanks to the pH that it buffers at. Since it buffers around pH 7.1, we can simply add excess bicarbonate to strengthen the buffering capacity of the water, at a pH that is optimal in all but extreme cases. We haven't really strengthened the ability of bicarbonate to buffer, _per se_ (it's still just bicarbonate), but we have the advantage of excess. We can continue to add more and more bicarbonate while still being buffered at pH 7.1, but as we add more bicarbonate, we then need more H+ ions to push the water into an acidic state. Effectively, we've increased the buffering capacity of the water.

Carbonate (CO3) is a strong buffer. It has the ability to bond with two H+ ions which means that for carbonate to form an acid, it must bond with two H+ ions. Bicarbonate only has to bond with one H+ ion to form an acid, since bicarbonate already has a H+ ion attached.

So back to the H+ ion. It should be clear that we can also simply add excess H+ ions to strengthen it's buffering capacity. Again, we don't strengthen the ability of H+ to buffer (it's still just H+), we just rely on an excess amount of the ion to buffer against a larger amount of carbonate. Of course this will buffer the water at a pH that is not optimal in our aquariums. But what might not be so obvious, is that H+ and CO3 have a similar property. Since CO3 will buffer the water at a very high pH, we must have an acid source to bring things into balance at the pH we desire. This acid source will react with CO3 to form HCO3, and hence, balance pH at a lower pH (then what CO3 would otherwise want to buffer at). This happens all day everyday in our aquariums with the acid forming reactions of life, and we offset the reduction in carbonates with water changes, and/or the addition of (bi)carbonate.

What should be becoming clear is that we can also reverse this process, by having excess H+ ions, and offsetting the pH that this H+ ion wants to buffer at with some amount of carbonate, we can end up at a higher pH then what H+ wants to buffer at, since some portion of this H+ will be converted to bicarbonate. 

In nature, these things work well and somewhat easily, thanks in no small part to excess. Nature has an excess of everything. Excess water, excess carbonate, excess H+, with the various sources of water across the planet simply having an even larger excess of one or more of the ions, then the others, and hence, having different equilibrium's, and hence, different pH. What is also important to understand, is that while some water sources in nature may have a low concentration of CO3, they have a constant supply of this CO3.

So back to our dinky little few liters of storage capacity, otherwise known as aquariums. What should hopefully becoming clear if you want to buffer the water at a low pH is two important factors. 

Don't strip out all of the carbonate sources.
You need excess H+ ions.

We can then lump these two factors into one final factor, balance. It's all about the balance of the various forms. Remember at pH around 7.0 and up, it's very easy to maintain balance, since an extreme excess of bicarbonate only causes an increase in TDS. In essence you don't have to pay much attention to balance, since the balance is easily maintained through excess of bicarbonate, and bicarbonate alone.

At low pH, I cannot emphasize enough the importance of balance. We have to manage the balance between H+ and HCO3, but also the balance between H2CO3 and CO2 + H2O. Not only this, but as per my banana and orange analogy above, as we reduce one (or both) side(s) of the scale, it becomes easier to tip the scale to the extreme in one direction. ie: It's easier to lose balance.

My advice to anyone wanting to reduce pH.

Don't strip carbonates. You must maintain some amount of carbonate to balance the equation. Excess carbonate has the advantage of stability, with the disadvantage (in terms of reducing pH) being the buffering of water at a higher pH. Don't take a shortcut and simply reduce carbonate sources, since this simply brings you closer to losing balance. Instead, increase acid sources. Force the supply of H+ ions in the water higher to offset available carbonates. This increases the available supply of each, and hence helps to maintain balance. Once you can no longer increase the supply of acid sources, then consider reducing carbonate levels.

Notice that I don't describe H+ and CO3 as concentrations, but rather, sources. As I described above, while some water sources in nature may have a low concentration of CO3, that concentration is consistently maintained through the available supply of CO3. In nature, this is easily maintained since nature provides an excess amount of water changes, and thus, flushing out excess build up.

In our closed loop aquariums where no flushing occurs, mineral levels _*will*_ gradually increase or decrease, and thus, maintaining balance becomes harder. In other words, maintaining low pH is significantly easier to accomplish with a constant water change system, since excess mineral levels are also constantly flushed out of the system, and it becomes significantly easier to maintain supply of the minerals that nets the desired equilibrium at any one point in time, _and over time_.

Don't panic. If pH continues to decline, it is simply because carbonate levels are dropping. If you panic and add bicarbonate (heaven forbid), you will raise pH, but two things occur. You bounce the mineral levels by large amounts, an we now know that it is these large shifts in mineral levels that cause aquatic life problems, not the pH _per se_, either the pH level, or the pH changes. In this situation where acid supply is high, bicarbonate effectively becomes a pH down problem where carbonate supply is high. That is, the bicarbonate will raise pH, the acid will quickly convert the bicarbonate to acid (since bicarbonate is a weak buffer), and you're back to square one. So you keep adding bicarbonate which only feeds the acid sources for a short time, and hence the only thing you effectively do is bounce the mineral levels up and down.

edit: Bicarbonate can be used, but it must be added in slow doses and consistently over time to mimic a constant supply, and prevent large fluctuations of mineral levels. 

Instead, add a carbonate source such as CaCO3. The poor solubility of CaCO3 means that it will provide a steady and constant supply of carbonate. It won't bounce mineral levels around, since it takes significantly longer for CO3 to convert to acid then HCO3 (bicarbonate).

Really, the only difference between acid buffering and alkaline buffering, is simply that everything is in reverse.

Now, a little disclaimer over and above the one in my sig. This is the theory as I understand it. I feel comfortable enough with my understanding of the theory to share this understanding, without worry that I will lead people down the garden path, or otherwise, that those who follow any advise I have listed above, will run into catastrophe. However, it should be noted that I don't currently have the desire to put this theory into practice myself, and regardless, people shouldn't believe everything they read. My intention is to increase the knowledge level of the community as a whole, but if you follow my recommendations and things turn to s***, you accept that full responsibility lies on your own shoulders, and your shoulders alone, for not sufficiently researching the issue yourself, and simply trusting my understanding of the theory.

Having said that, I do maintain the system I describe above. That is, I target a _supply_ level of things I want in my aquarium, and flush out excess with a constant water change system. The differences are that I want to maintain a large amount of CO2 in the water, which allows me to have excess carbonate for the same pH, and thus, provides a larger safety margin.

Hope this helps.


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## Linwood (Jun 19, 2014)

Thanks for all the background, I'll digest later have to run out for most of the day.


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## end3r.P (Aug 31, 2015)

Lots of good stuff here, thank you. Two takeaways for me as a practical matter:



Audionut said:


> Instead, increase acid sources. Force the supply of H+ ions in the water higher to offset available carbonates. This increases the available supply of each, and hence helps to maintain balance. Once you can no longer increase the supply of acid sources, then consider reducing carbonate levels.




So, keep some carbonates in the system, and add an acid buffer source to get to a lower pH and buffer against swings. What can I use for these two steps? Is calcium carbonate in any Seachem products? I need to add these when I do my water change so the RO water doesn't greatly change the water chemistry, so throwing natural things like crushed coral and Indian almond leaves into the tank won't work. I mean, I could do that, but I also need something to add to the RO water to match tank water. 



Audionut said:


> Having said that, I do maintain the system I describe above. That is, I target a _supply_ level of things I want in my aquarium, and flush out excess with a constant water change system. The differences are that I want to maintain a large amount of CO2 in the water, which allows me to have excess carbonate for the same pH, and thus, provides a larger safety margin..


CO2 is looking like a better and better option.... I avoided it since it adds another complication to the process, but it might be an easier way to keep a stable acidic pH....


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## end3r.P (Aug 31, 2015)

Also, how do products like Seachem's phosphate-based Neutral Regulator and Acid Regulator fit into this framework? They say they're very stable buffers that work by "precipitating" calcium and magnesium...


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## Audionut (Apr 24, 2015)

end3r.P said:


> So, keep some carbonates in the system, and add an acid buffer source to get to a lower pH and buffer against swings.


Correct. You will need to reduce carbonates to a low level, but the point I want to enforce for people looking to get their feet wet, is to make the reduction of carbonates the final process in achieving a low pH, after all of the other pieces of the puzzle have been laid.

Tank life creates acid and we add carbonates to buffer against this acid production. By increasing acid production (with acid sources) we effectively negate this acid production by life, since our acid source is far in excess of the acid source produced by life.




end3r.P said:


> Is calcium carbonate in any Seachem products?


No. Calcium carbonate is only available in solid form. It's solubility is very poor.




end3r.P said:


> I need to add these when I do my water change so the RO water doesn't greatly change the water chemistry,


If you setup a constant water change system, you don't need to add anything to the RO water. Here, we can use the power of dissolution to negate the differences in water chemistry.

The water then becomes another source in the balance equation. Acid production + carbonate production + water injection

This is by far the easiest method, since you don't have to consider the long term effects of build-up by your acid and carbonate sources. These sources effectively cannot build-up, since they are constantly being flushed with fresh water, and of course, you don't have to try and match source water with tank water for water change.

Apart from the other obvious benefits in not having to perform water changes and prep source water, this method will also allow you to have low pH with natural sources, without the tannic acid look to the tank. I'm currently doing around 12% per day water change with a drip system based on the results of this calculator, with nice clean water, despite the tank having a decent amount of somewhat fresh wood in it, and both my sumps also having decent amounts of fresh wood.




end3r.P said:


> so throwing natural things like crushed coral and Indian almond leaves into the tank won't work. I mean, I could do that,


You will need to do that. You need to control the conversion process between H2CO3, HCO3 and CO3, which means you need to balance the sources of each.

Remember, at pH 7.0+ we rely on excess bicarbonate to buffer pH, and we don't have to worry so much, because this excess itself isn't an issue. Bicarbonate buffers at a desirable pH.

H+ doesn't buffer at a desirable pH, instead it buffers the pH very low. We can't just throw in tons of acid and call it a day, as we somewhat can with bicarbonate.




end3r.P said:


> but I also need something to add to the RO water to match tank water.


Yes. You will need to prep the source water. This will mean adding acid sources to increase the H+ concentration. Since KH test kits will be unreliable in this situation as they're likely to measure the organic acids, you will need to experiment to find the correct amount of bicarbonate to add.

For reference, 1.2 grams of NaHCO3 (sodium bicarbonate) or 1.4 grams of KHCO3 (potassium bicarbonate) per 10 gallons will raise dKH by one. This will also add 9ppm of sodium if using NaHCO3, or 14ppm of potassium if using KHCO3.

If you have time, you can also use things like shell grit to prep your course water. By making the prep water acidic, this will increase the rate at which shell grit dissolves. However, I know of no reliable way to determine carbonate levels in this situation. Your KH test kit is likely to lie about it's results. You would have to trial and error.

To determine if you have your source water correct, monitor the tank pH. If the pH rises with water change you have to much bicarbonate, and if the pH drops you do not have enough bicarbonate.

You can also use pH to monitor the tank on a day to day basis. If pH rises, your carbonate sources are greater then your acid sources. If pH drops, your acid sources are greater then your carbonate sources.




end3r.P said:


> CO2 is looking like a better and better option.... I avoided it since it adds another complication to the process, but it might be an easier way to keep a stable acidic pH....


It is by far the easiest solution. pH to high, adjust the needle value a little. pH to low, adjust the needle value a little. To easy.

However, consider this post by Zorfox. 

In a nut shell, if you want low pH for some specific fish, the fish probably doesn't care so much about the pH, instead, it's the low mineral levels typical in low pH water that the fish probably really cares about.

What CO2 does do in this situation though, is allow you to maintain a slightly higher level of _just one_ specific mineral, bicarbonate, for safety, while being able to keep pH low.

I say "probably" alot here, because as far as I know, there is no hard (scientific) evidence to say it's _only_ the low mineral levels that matter for these fish. Ions react differently at different pH, and until I see evidence to suggest the manner in which ions react at different pH doesn't concern fish, then I'm not willing to right off pH as inconsequential.

It's a little like the temperature debate. Fish who are accustomed to low temperatures will be fine in higher temperature water. Yeah probably. You might be able to survive at a constant 110 degrees, doesn't mean you will like it or thrive at that temperature though.



end3r.P said:


> Also, how do products like Seachem's phosphate-based Neutral Regulator and Acid Regulator fit into this framework? They say they're very stable buffers that work by "precipitating" calcium and magnesium...


No idea. I have no interest in using these, or using phosphate as a buffer.


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## Audionut (Apr 24, 2015)

Correction: Calling H+ a buffer, or describing it as a form of alkalinity is just plain wrong. H+ does not have the ability to neutralize an acid, funnily enough, probably because it is an acid. 

I'll find some time to rewrite the above, since it is misleading in it's current wording.


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## Hardstuff (Oct 13, 2012)

Surprised there is no mention of trace in this thread? Fluorine, selenium, zinc,iodine to name a few. When people usually mention remineralizing R/O with Gh booster and KH buffer they almost always forget the trace! I am confused why people do not add trace back in especially when using 100% R/O? Seachem fish trace is what I have been using for years with good results.


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## Bainreese (Oct 2, 2015)

Since I have relatively hard municipal water I filter with RO/DI. I've had varying results using Seachem's Acid & Alkaline buffers in trying to reach a desired pH. I've found the above conversation very enlightening. From this I believe I will begin using Equilibrium to reach a desired GH and baking soda to reach a desired kH and then use CO2 to reach a desired pH.

It sounds like dialing in the GH and kH with those two additives and not worrying about the pH as much is more desirable for the health of the plants and fish than stressing over setting the pH right with my storage water.


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## end3r.P (Aug 31, 2015)

Hardstuff said:


> Surprised there is no mention of trace in this thread? Fluorine, selenium, zinc,iodine to name a few. When people usually mention remineralizing R/O with Gh booster and KH buffer they almost always forget the trace! I am confused why people do not add trace back in especially when using 100% R/O? Seachem fish trace is what I have been using for years with good results.


I use Plantex CSM+B, which supplies some trace elements. Everything in Seachem Fresh Trace except fluorine, selenium, and iodine. Anyone know whether I need to add Fresh Trace or something like it just for these three, for fish health?


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