my alkaline water is acidic x.x

[JohnPaul]

Hrmmmm....

My tap water is alkaline, usually around 7.4 out of the tap. It is also soft, with dKh readings typically coming in between 1.5 and 2.5.

Within this last week I set up a 10g RCS tank and have about a dozen or so RCS (from adults to juvies) in it. They all seem happy, swimming around, constantly moving, scouring every surface for food, etc. While the tank itself is new, the filter is a cycled sponge filter and the plants are all from other tanks as well, so it seems the shrimp are finding enough to eat and in all ways are pretty happy.

So imagine my shock when I measure the pH of the tank and it comes up around 6.0! The only thing I can think of is that the two chunks of driftwood are leaching acids (tannins) into the tank. The thing is, the water is not the *slightest* bit yellow. Not even a tad. It's as clear as clear can be. Yet, the pH is off-the-charts low. All other water specs are idea (zero ammonia & N02, NO3 <= 5 pm).

So question #1 is, are there such thing as "invisible" tannins? If not, what else could be causing this? The only other "new" thing in the tank is the substrate, Tahitian Moon Sand, which is supposed to be chemically inert, and a couple of small "rocks" (look more like chunks of colored glass).

Question #2 is, whatever the cause might be, what do I do about it? Should I attempt to do more frequent water changes (to bounce the pH up) or is that simply going to send the poor guys into pH shock more often?

Long term, I'm really hoping these guys breed, so I realize I need to figure out what's going on. Short term, though, my real question is whether I should do frequent water changes to try to keep upping the pH, or just leave things be.

TIA...

[zapisto]

add some crush coral in it .

[Mustafa]

Not all organic acids have color. Many organic acids that driftwood can leach are cololess. Also, since your water has barely any alkaline buffering it's easy for the nitrification process to drive down your ph by producing nitric acid. Your approximate 5 ppm nitrate reading tells me that you probably have quite a bit of nitric acid in your water.

Anyway, using crushed coral will resolve the issue "on the surface" but you need to find the source of the acids and eliminate them as your water out of the tap is in the alkaline range already.

[ToddnBecka]

Try aerating some tap water in a separate conatiner for 24 hours, then check the pH. It may be naturally acidic to begin with, treated by the water dept. to raise the pH, but unstable in the long run.
Crushed coral in the tank, or in a filter, will raise pH to around 7.6, and buffer it as well.

[pturley]

edit.

[badflash]

My experience with granite is that it is neutral when it comes to aquariums. While it is true that feldspars weather to clay, this process is very slow and nothing like the breakdown of carbonate rocks.

Have you tested this, or are you basing it on water that comes from granite bedroock that is soft and therefore tends to be acidic. The acidic nature of this water is not due to anything the granite adds, but for it it doesn't add. namley much of anything.

[JohnPaul]

Try aerating some tap water in a separate conatiner for 24 hours, then check the pH. It may be naturally acidic to begin with, treated by the water dept. to raise the pH, but unstable in the long run.
Crushed coral in the tank, or in a filter, will raise pH to around 7.6, and buffer it as well.

That possibility occurred to me, but my main tank (29g community) which has been set up now for 2+ years is very stable at around pH 7.2, and that is with no "treatment" or buffering of any sort. This tank has several very large chunks of driftwood as well. And when I leave tap water sitting out in a bucket overnight, it still measures in the 7.2-7.4 range, so I think that is the inherent pH of the water. Just seems that, since it is so soft, it can very easily be thrown off by anything acidic.

[ToddnBecka]

I'd toss in a handful or two of crushed coral, to raise the KH and counter the acidity. It will raise the pH and hardness gradually, partial wc's in the meantime to help the current situation.

[badflash]

Large tanks with substrate can control the pH to a large degree in my experience. The bacteria "lock in" to a pH that is best for them and they actively control it. It ends up sort of like a radio channel and you have to work actively to "change channels" if you need a higher or lower pH. Adding acid or base daily for a week or two is needed to establish a new baseline of bacteria.

[Mustafa]

Large tanks with substrate can control the pH to a large degree in my experience. The bacteria "lock in" to a pH that is best for them and they actively control it. It ends up sort of like a radio channel and you have to work actively to "change channels" if you need a higher or lower pH. Adding acid or base daily for a week or two is needed to establish a new baseline of bacteria.

Did you make this up as you go ( ) or is there any kind of scientific evidence out there that bacteria can control their own ph? For that to happen the bacteria must somehow be able to release BOTH acids and carbonates/bicarbonates/other alkalinity builders to drive the ph up and down to their preferred value. They can't just produce these out of nowhere. I think i've written it elsewhere (another thread) as a reply to your bacteria theory before, but here it is again: If you add acids to decrease the ph you must overcome the buffering ability of alkalinity builders such as bicarbonates. That's why you will seet he ph rebound for a while until the buffering ability is overcome. You might want to look up "buffering" and "ph" and "water chemistry" in a major search engine to read up a little bit more about how ph can be controlled and why it works the way it works. It's really not the bacteria locking into anything. It's chemistry.

[badflash]

No more scientific than using oak leaves, but yes there is plenty of evidence in science that a biosphere controls its own environment. Rain forests make their own weather where such weather doesn't belong, Our bodies control temperature, salinitity, pH etc. Ever studied coral reefs? They build up on top of themselves, yet can only survive in a vary narrow depth. As one layer build on the next the crust actually sinks into the sea and maintains a constant depth. Life is not totaly at the whim of the environment. Pine trees produce acidic needles to control the pH they need, lots of example like that out there.

I have many tanks with all the same substrate, same make-up water, different pH. Most established their own pH, some I forced. Once the pH "locks in" there it stays. Maybe you can explain it. All I know is it happens and after that I just make educated guesses. Bacteria can produce both acid and base to control their environment. Kill of the bacteria in your gut and see what happens.

I have a large gravel substrate with my undergravel filters as opposed to your bare bottom tanks with sponge filters. I think these are very different situations.

I do understand buffering, pH and how to change them. I did a lot of reaserch last year and have a working knowledge of it now between my aquariums and my swimming pool. The bio load is the wild card. The critters will set things up to make life easy for themselves.

[Mustafa]

No more scientific than using oak leaves

Actually, using oak leaves (and other leaf litter) is very scientific. For one, there are plenty of reports both from scientific papers and from hobbyists, who caught shrimp in their natural habitats, that shrimp live in and feed off of leaf litter in most habitats. Also, there is *tons* of evidence that bacteria and other microorganisms grow on and decompose leaf litter. Also, there is TONS of evidence (i.e. scientific papers) that invertebrates, such as shrimp, eat the bacteria and also the leaf litter directly.

Here is a direct quote from one of literally hundreds (maybe thousands?) of papers dealing with this issue:

"Leaf litter decomposition in streams is an important ecosystem-level process, which depends on the activity of invertebrates and microorganisms. Both fungi and bacteria convert leaf carbon into microbial biomass, enhancing leaf palatability for shredding invertebrates."

Source:

http://www.pubmedcentral.nih.gov/articl ... tid=520852

Dwarf shrimp are "shredding invertebrates" by the way, in case anyone has not made the connection yet. See? It's all very scientific.

but yes there is plenty of evidence in science that a biosphere controls its own environment. Rain forests make their own weather where such weather doesn't belong, Our bodies control temperature, salinitity, pH etc. Ever studied coral reefs? They build up on top of themselves, yet can only survive in a vary narrow depth.

All these things can be explained and have been researched and we all have an idea on what the mechanisms are. I'm just saying that there is absolutey *nothing* (at least nothing I am aware of) about bacteria locking in some ph value in any aquatic environment.

I have many tanks with all the same substrate, same make-up water, different pH. Most established their own pH, some I forced. Once the pH "locks in" there it stays. Maybe you can explain it.

Yes, I can...as I have explained it before! Even different nitrate levels (nitric acid, which is very strong!) can contribute to different ph values in otherwise acidic tanks. Different levels of accumulated organics (which can produce various organic acids) in your filter can contribute to different ph levels...etc...etc....etc...there are tons of reasons why two tanks with the same tap water and substrate don't have to have the same ph. In the end all can be explained with water chemistry.

All I know is it happens and after that I just make educated guesses.

Guesses are not a good idea most of the time. You can hypothesize, but your hypothesis should have some grounding in reality. I don't like promoting total speculation here, as the danger of someone reading it here and going around spreading it elsewhere is pretty large. And then...a few years from now you'll still read people saying "I think my bacteria finally locked in my ph".....just like you still read people talking about adding iodine in their tanks because they "heard" it's good for shrimp.

Bacteria can produce both acid and base to control their environment. Kill of the bacteria in your gut and see what happens.

Ummm....the bactaria don't produce the acid (which is hydrochloric acid by the way). Cells called "parietal cells" on the "mucosa", which is the inner layer of the stomach produce the acid. See again? You speculated above by implying my stomach bacteria produce acid (which they don't) but many things can be explained pretty simply once one does the reasearch.

I have a large gravel substrate with my undergravel filters as opposed to your bare bottom tanks with sponge filters.

I only have one real bare bottom tank right now...the rest have a thin layer of substrate. But that does not make a different in the above discussion....even if you have *more* bacteria in your substrate they still don't "make" the ph.

The bio load is the wild card. The critters will set things up to make life easy for themselves.

Unfortunately the critters are not the bacteria. The critters are critters that produce nitrigen compounds, such as shrimp, which then turns up as nitric acid after bacteria turn ammonia and nitrite into nitrate. Yes, bacteria make the nitrate, and so in a sense "produce" acids (as a byproduct), but they don't regulate anything as you implied. If you never make water changes and keep feeding your shrimp, your bacteria will keep making more nitrate...and if nothing eats up the nitrate or neutralizes it (i.e. alkalinity), your ph will keep dropping....I've seen it happen...no regulation happening there.

Again....I am so adament about these things because I just want to make sure that even if we are making "educated" guesses we should base such speculation on real things to avoid creating even more myths in the hobby....we all know that there are already enough myths out there. If you are hypothesizing or speculating you really want to indicate that and list the reasoning for your hypothesis/speculation so that others have a chance to confirm it or disprove it. Remember the peer review process....

[badflash]

I only have one real bare bottom tank right now...the rest have a thin layer of substrate. But that does not make a different in the above discussion....even if you have *more* bacteria in your substrate they still don't "make" the ph.

I'm not sure a thin layer just sitting on the bottom is anything like a 2" layer on top of an under gravel filter with active flow going through it and the waste being digested in the substrate.

You are saying that the shrimp are adding nitric acid directly via their excretion? I'm not getting that part. I had a pond filter in my 300 gallon pool that was overloaded with goop. Flow was still good. I tested my pH and hardness. Water was hard as a rock and loaded with calcium. The bottom is covered with coral and coral rocks. pH was 6.5. I pulled out the filter and cleaned it and did my normal weekly water change. The pH bounced back to 7.4 after a couple of days and has stayed there. Other than the bacteria in the filter, where would the acid be comming from?

[ToddnBecka]

The decaying "goop" that the bacteria were feeding on, producing the acidic conditions. The same thing can happen to an aquarium that's been running for some time w/out sufficient cleaning (old tank syndrome).

[badflash]

The decaying "goop" that the bacteria were feeding on, producing the acidic conditions. The same thing can happen to an aquarium that's been running for some time w/out sufficient cleaning (old tank syndrome).

But isn't decay caused by the bacteria? That is why I'm thinking it is the bacteria that is adding the acid.