Need to get the pH down - The Planted Tank Forum
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post #1 of 45 (permalink) Old 09-08-2014, 09:12 PM Thread Starter
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Need to get the pH down

So I have boiled leaves, inserted driftwood, used peat moss, my pH is still at 6.5.

I need to get my pH down to at least 6. Any suggestions that don't involve pouring in chemicals?

Thanks!

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post #2 of 45 (permalink) Old 09-08-2014, 09:14 PM
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Need a lot more info here...

What size tank? Is it cycled? How long has it been set up? How long have you had the driftwood and peat moss in the tank/filter? What "boiled leaves" are you using — Indian almond leaves? Any fauna in the tank right now?
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post #3 of 45 (permalink) Old 09-08-2014, 09:32 PM
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Why do you need your ph so low??
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post #4 of 45 (permalink) Old 09-08-2014, 10:29 PM
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It is rarely necessary to achieve a specific pH in an aquarium. Much more important is getting the right range for hardness, GH and KH. As brooksie321 asked, why do you want such a low pH?

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post #5 of 45 (permalink) Old 09-08-2014, 10:39 PM Thread Starter
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Size: 29 gallons
Almost Completely Cycled - a smidge of ammonia is present
1 Month Set Up
Peat Moss = 3 Weeks
Driftwood = 3 Weeks
Boiled Leaves = Oak and Maple
kH = 80 ppm
gH = 120 ppm
(Test Strips)

Reason: I am running a Rio Negro tank and my darn rare plants want a low pH.

Fauna: 5 Cardinal Fish (so far) and 4 Pencilfish (so far)

If I add RO water, will that take down pH?

Thanks.
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post #6 of 45 (permalink) Old 09-08-2014, 10:57 PM
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Smile Data! Data! Data! We Must Have Data!

By definition RO water should be right around pH 7, so no it will not bring down the pH, but it will not add alkalinity that buffer the water.

'It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.'
Sherlock Holmes Quote,-A Scandal in Bohemia


It is the alkalinity (KH) to focus on. RO may help by replacing higher KH water.

If you do not already own an RO filter, it may pay to look at the other options.

What is the KH out of the tap (your source water)?

Time may take care of this problem.

What are using for substrate?

What is the driftwood? This can sometimes be a problem.

Rock? Be careful of rocks they often add buffering (alkalinity).

I you could kindly share with us the type of plants, some may be able to help.

Joe
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post #7 of 45 (permalink) Old 09-08-2014, 11:09 PM
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Surely your tank can function around 6.5?? Below 6 will affect your bio filter. .
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post #8 of 45 (permalink) Old 09-09-2014, 12:48 AM
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Make a blend of RO + Tap water. (perhaps make a couple of test batches at different ratios. Test GH, KH, TDS and pH. Work with the one that results in the softest water that is the closest to what you want. With GH = 80 ppm and KH = 120 ppm you will probably be mixing no more than 25% tap water + 75% or more RO. This will probably drop the GH too low, but will lower the KH into a reasonable range so it is not trying to raise the pH back up.

1) Set the GH right for the fish. Couple of degrees max in this case. (there are 17.9 ppm in 1 German degree of hardness, so a dip stick reading not over 40 is about max for what you want to do.)
2) Make the KH match the GH. (Hopefully the blend of Tap + RO has dropped the KH low enough. If not, add more RO.)
3) pH will be a lot lower, and a lot easier to change. You can further drop it by filtering through peat, adding oak or other leaves and twigs, adding driftwood (some works better than others).

But the first thing to understand is that it is the mineral levels that you need to correct. pH is secondary. The obligatory soft water plants do not want much calcium in their water, and Cardinal Tetras are the same way. The first target therefore is the GH.

Get the plants really well established. The nitrifying bacteria will be almost worthless if you drop the pH below 6.5.
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post #9 of 45 (permalink) Old 09-09-2014, 03:22 AM
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One thing I've learned over the years is not to mess too much with water ph. It is a battle you rarely win if using tap water.

Have you tested the ph of your peat? Put a bit into a small amount of water. Give it abit of time to steep. Check the ph. Whatever that ph is is the lowest it can bring your water's ph to. And generally won't get it to that point.

As an example. ph of Baking powder is 8.5. No matter how much powder you add to water it will not go above 8.5. Same thing in the opposite direction. So if the ph of your peat is 6.5 you can't get it lower than that.

Dilution is the solution for the pollution.
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post #10 of 45 (permalink) Old 09-09-2014, 04:41 AM
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Smile What Diana Said

Apologies for commenting obviously Kh could have nothing to do with pH in tanks

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post #11 of 45 (permalink) Old 09-09-2014, 07:19 PM
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Smile AmazingWhatYouCanDoWhenYouDon'tKnowYouCan't

I apologize for my last post, frustration I guess.

Let me begin by saying I do not pretend to be nearly as smart as the folks telling you, you cannot successfully keep plants and fish in water below pH 6.8 or 6.5.


All I can do is relate my experience and that of others, apparently not smart enough to know it cannot be done.

Now just to cover some technical stuff so as not have it attacked the description I am offering is for water at 25°C (77°F) the major factor in the ionized, un-ionized ammonia is primarily dictated by the pH, but temperature is a factor. Remember that the definition of pure water being pH 7 is true at 25°C.

Keeping tanks at pH 5.8 – 6.0 is a little more work, but in a well planted tank with soft water loving plants and fish that are happy in this environment.

  • Keeping the plants happy is your main concern since they are going to deal with the ammonium directly.
  • Consider that unlike ammonia, ammonium (ammonias’ ionized form) is pretty much non-toxic.
  • Without getting too technical, understand that ammonium and ammonia constitute a conjugate acid-base pair.
  • Unless you are interested in chemistry the only thing to remember is that over a pH 8 almost all of the ammonium/ammonia (total ammonia) is in the form of ammonia (the un-ionized form)
    • and is incredibly toxic.

When the water (in textbooks the term aqueous solution is used) is



  • at pH 7 or less the total ammonia is mostly in the ionized form, ammonium.
  • While it is true that under pH 6.5-6.8 our biological filtration ceases (actually it changes, but I don’t want to argue about it),
  • once your pH is under 6.5 the total ammonia is nearly all the ionized form, ammonium.
  • Plants tend to be able to use ammonium directly.
  • No need for the Nitrification process (the process takes a bit different form)
  • thiobacteria live well into low pH so the sulfur cycle continues.

I do not understand Diana’s advice regarding keeping the KH the same as the GH, I love her books and she is obviously much smarter than I can ever hope to be, but my experience (and education) suggests that KH, carbonate hardness, alkalinity, is the buffer (thing that resists lowering pH) and principal factor in determining pH, therefore the ammonium/ammonia relationship.


Time may prove the pH will lower on its own. You are using chemicals, to lower the pH, but I understand what you mean in not using chemicals.


The use of reverse osmosis/deionized (RO/DI) or distilled water, mixed with tap water if possible, well aerated, with electrolytes added, temperature matched.



Since you will require regular water changes especially in the beginning, making up batches of water in advance and storing with an air stone to keep it well aerated.

Joe
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post #12 of 45 (permalink) Old 09-10-2014, 03:22 AM
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I am not Diana Walstad.

Here is the reasoning behind keeping the GH and KH sort of close to each other:

There is not really a direct connection between GH and pH, but the indirect connection is this: The minerals that we read as GH are Ca and Mg. In nature they are most common as calcium carbonates and magnesium carbonates. Where you find lots of Ca or Mg in the water, you also find lots of carbonates or bicarbonates.

In areas of the world with lots of limestone and related materials, low rainfall, high evaporation rates (usually a combination of all 3) the rain dissolves the minerals and the water is high in both GH and KH.

In areas of the world with LOTS AND LOTS of rain, the minerals have:
a) Been washed away a long time ago, leaving only minerals that do not dissolve very much. The GH and KH in the water is very low because not a lot of limestone or related materials are still there to be dissolved.
b) Are still dissolving, but are so highly diluted by the copious rain that the GH and KH in the water is very low.
In either case the GH and KH are both very low.

There are other spots, where GH and KH are nowhere near similar to each other, but these are so few, and so small, that most people do not keep fish from those areas.

Lets return to the case where there is little rainfall, high levels of limestone or related minerals, and high evaporation. This sort of environment is not friendly to plants, so the land surrounding the lakes and rivers does not drop a lot of organic matter into the water. Not much runs off the land because there is not much growth, there is not much rain, what rain there is soaks into the soil instead of running off.

Fish from that sort of water are acclimated by evolution to hard, alkaline water with high TDS.

Now lets return to the high rainfall area.
This area is lush with plant growth. Plants drop leaves and branches, and whole trees onto the forest floor, and into the rivers. The rivers may flood out onto the forest floor. Remember these waters have very low levels of minerals and are now being exposed to high levels of organic matter. Organic matter tends to add acids to the water. Several organic acids, and the acid reaction of decomposition. When the water is so low in KH, the end result is very acidic water.

-----------------------------------------------------------------------------------------

So, take your pick:

Fish that have evolved in soft (low GH) water are also acclimated to acidic water (low pH). That is the way the water is in their habitats.

Fish that have evolved in hard (high GH) water are also acclimated to alkaline water (high pH). That is the way the water is in their habitats.

Sure there is a middle ground. GH and KH in moderate levels, and pH not too far off neutral.

However, this post is specifically about the plants and animals that are from very soft water that is acidic.
The way I have made this sort of water is to start with RO and blend some tap water to get just a few minerals, setting the GH and KH about 2 German degrees of hardness. Then filter that through peat, or add oak leaves and twigs, or driftwood. Something organic to add the organic acids.

In other words, set the GH to the optimum level for the fish. Other people have figured out that the GH is the most important factor for keeping fish healthy. There are a few plants that are also very picky about their water, and these plants do not thrive with high calcium in the water.

Then set the KH about the same, because that is what you find in nature.

By setting the KH similar to the GH the pH will usually follow: Acidic in the soft water tanks, alkaline in the hard water tanks.

----------------------------------------------------------------------------------------------------------------------
Here is one report about certain lakes in temperate zones. Scroll to page 303 (about the 5th page down) and see the chart graphing Ca and Mg vertically and alkalinity horizontally. See how the values tend to cluster in the middle line?
http://aslo.info/lo/toc/vol_3/issue_3/0299.pdf

Last edited by Diana; 09-10-2014 at 03:34 AM. Reason: Added link
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post #13 of 45 (permalink) Old 09-10-2014, 03:34 AM
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Smile Complete Misquote

Quote:
Originally Posted by GraphicGr8s View Post
One thing I've learned over the years is not to mess too much with water ph. It is a battle you rarely win if using tap water.

Have you tested the ph of your peat? Put a bit into a small amount of water. Give it abit of time to steep. Check the ph. Whatever that ph is is the lowest it can bring your water's ph to. And generally won't get it to that point.

As an example. ph of Baking powder is 8.5. No matter how much powder you add to water it will not go above 8.5. Same thing in the opposite direction. So if the ph of your peat is 6.5 you can't get it lower than that.
Of course I am speaking in aquarium temperatures ranges and specific examples are at 25C°, 77°F. In all cases temperature plays a minor role, higher temperatures slightly increase pH, lower temperatures slightly decrease pH. In all cases we are considering aqueous, that is water solution, freshwater as that given the nature of our aquariums. The examples assume pure water, pure whatever else.

Since baking soda, Sodium Bicarbonate (NaHCO3) will only add enough buffering to get you to pH 8.4 maybe pH 8.5.

  • We know it only has enough of the diatomic anion, Hydroxide (OH-) to except enough of the cation, hydron (H+) to maintain a pH of maybe 8.5.
  • We consider baking soda a weak base.

To go further we can add washing soda, Sodium Carbonate (Na2CO3), if interested Baking soda can be transformed to washing soda with a couple of hours in the oven at 200°C (call it 400°F) for an hour or so.

  • Actually this can be accomplished in a longer time in a much cooler oven, as in 94°C (call it 200°F), I have heard of hobbyists drying (reviving) baking soda, never exceed 65°C (~150°F) when drying to dry baking soda.

Sodium Carbonate is a strong base and can take the water to a pH 11.6 (using baking soda in the oven I end up with pH 11, maybe a bit higher, Arm & Hammer® from the store gets me about pH 11.6) this of course means that it is a strong base. Essentially washing soda remove takes up twice as much (equivalent) acid.

I went through all of this to ask what GraphicGr8s, Supreme ruler & master point was, fully misquoting him above. The answer is that if we want a different pH, we add or remove something else.

  • In the case of your baking soda example we simply drove off a little water and a little carbon dioxide to go from a weak caustic that limited us to pH 8.5 to a strong caustic that would allow us to manipulate the pH up to pH 11 or so.

Joe
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post #14 of 45 (permalink) Old 09-10-2014, 03:43 AM
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Joe, I've read your post 5 times. What on God's green Earth are you talking about? How does this help any one other than you for self edification?

Also in this sentence
Quote:
We know it only has enough of the diatomic anion, Hydroxide (OH-) to except enough of the cation, hydron (H+) to maintain a pH of maybe 8.5.
the correct word may be accept, to receive. Except would be let everything else in BUT that. They are homophones that mean exactly the opposite of each other.

The point was that when you add something to change your ph you can never get the ph below (or above) the ph of what you are adding. If you add vinegar to water it will never get below the ph of said vinegar. In fact it will never even get to that point since you are diluting it.
IOWs if his peat is at a ph of 6.5 then no matter how long he leaves it there it will never get below 6.5.

Have you ever had pure water any place? Unless you're in a lab you haven't. In real life close is good enough.

Dilution is the solution for the pollution.
Quote me as saying I was misquoted.
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Last edited by GraphicGr8s; 09-10-2014 at 03:57 AM. Reason: jk
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post #15 of 45 (permalink) Old 09-10-2014, 03:53 AM Thread Starter
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I think I am actually lost now.

However, I plan to test the pH of the peat. :-) I plan to get back to you with the results. I am ordering Indian Almond Leaves which probably have a lower pH.

My weird plants are: Echinodorus Horizontalis, Echinodorus Angustifolius, Cabomba Furcata (not weird)

I also have normal stuff like salvinia oblongata, salvinia minima, and water hyacinth.

Looking for a pH of 6 and softer water. Although I guess I can settle for softer water.

Thanks.

dbw
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