Low or no KH and low PH without a "crash"??

[fresh_lynny]

ok ...well there was no reason for the pH to be so low. I even plugged in values and did some old fashioned chem equations, and it didn't add up. After the water change it didn't move...stayed at 5.8 hmmmmmm deductive reasoning....check the pH probe.....yep It was off by nearly a point. Well that stinks, so I was light on CO2 for the last day and a half. Parms now...6.7, CO2 5 per sec, KH 1-2....

[Raul-7]

I remember reading over an experiment where soft water Characins were kept in water with a pH of 5 all the way down to pH 2, and survived. Sure, some Blackwater species thrive in low kH/pH water, but others will suffer - namely those of you who keep Rainbowfish; they have shorter lifespans in acidic water.

[BlueRam]

pH crashes are real. Think of your favorite carbonated beverage with a pH ~3.
http://www.21stcenturydental.com/smith/pH_drinks.htm

You can also figure that a KH of 3 is safer via buffer chemistry:
http://en.wikipedia.org/wiki/Buffer_solution

Being contrarian is cool and all but at least get the chemistry right.

Originally Posted by fresh_newby

Whenever someone told me I had to adjust my kH or I would have a pH crash, I thought...that is utter BS. Makes no sense. In my belief, CO2 will only get your pH down so much, so how far down would it crash to? I believe 5.5 is about the limit, and with surface agitation and/or airstone, this shouldn't be a big deal, just remove your snails so their shells don't erode. I moved mine to my outdoor "pond"

[plantbrain]

The real question is not so much the crash, but does cause issues or is it a real problem?

When the KH==> 0 no buffer.
Adding a weak acid=> CO2 [aq] causes the pH to drop, but is the pH dropping due to this acid of any consequence to fish or plant health?

I'm not talking about ungodly high CO2 ppm's, just the issue of pH.

If you add 30ppm to a tank with 1 KH and then lower the KH to close to 0 with RO water etc and keep the same CO2 bubble rate etc, you should have the same ppm avail;able for the plants and the fish without the KH.

The CO2 never changed, but the KH did.

CO2 might be a tad less souble in the 0 KH, but that's about it. I doubt that's enough to cause any issues more than a couple of ppms.

I've been running several tanks for a few months at 0 KH, loads of fish/shrimsp(cherries and Amano's) etc.
No issues here.

So the KH was immeasurable via a Lamotte test kit which is good for 4ppm units. About 1/4 unit degrees.

pH does not apply since there is no buffer, you need a special probe for super soft water.

If you have no KH, then you cannot use the pH/KH chart and even a trace amount of other buffer systems and acids can really cause measurement havoc if you plan on using that relationship.

Something not often done when reports of fish from GH= 0, KH= 0 in the Amazon rainforest, they use the normal probes, not the specialized ones for purer water.

Regards,
Tom Barr

[jhoetzl]

Wow, I've often wondered how I have water with nearly immeasurable KH/GH most of the year (my water source changes at the end of the summer for a little while as far as I can tell),

One or two drops in a double solution on a KH and GH test is about as accurate as I have gotten...

My pH, according to a freshly calibrated phPep5, 5.6 or so...given the equipment cost < $100, lets say it is off by +-1...

Fish don't die, plants grow - I pump Co2 in with lights on, off with lights off. Airstone on overnight otherwise I get gasping fish in the morning. If I cut back the co2 to less to try and balance it, I get algae within a week.

I had been adding baking soda and seachem eq, but I just don't see the benefits and haven't been adding them for the past month's water changes with no ill effects.

Perhaps I should find some nice would to begin knocking on...

Oh yeah, and did I mention I have rainbows, and have spawed just about every livebearer (need hard water and higher pH - yeah right!) I've had my hands on.

[Hoppy]

Edward's original post on APC was intended to make us understand that it is very high CO2 levels that kill fish, not very low pH, which results from the high CO2. And, if you accept that, then avoiding a "pH crash" should not be a concern, but going too high on CO2 without careful monitoring to be able to quickly drop the CO2 back down when the fish don't look so well, should be our concern. He even added that he had dropped the pH of a low pH tank still further using peat, down to about pH3 as I recall, without the fish showing any problems. This led me and others to conclude that messing around with baking soda to "avoid a pH crash" was not a useful activity. But, we have all said that you just cannot jack up the CO2 level, go off to work and return in the evening, unless you have no problem with losing the fish.

[fresh_lynny]

Originally Posted by BlueRam

pH crashes are real. Think of your favorite carbonated beverage with a pH ~3.
http://www.21stcenturydental.com/smith/pH_drinks.htm

You can also figure that a KH of 3 is safer via buffer chemistry:
http://en.wikipedia.org/wiki/Buffer_solution

Being contrarian is cool and all but at least get the chemistry right.

Coke is not highly acidic just becuse of CO2...It has acid as an ingredient in addition to carbonation <CO2>. Release of CO2 makes it more basic. Our tanks are not under the same pressure as Coke is, nor anything that is carbonated and remains carbonated. This is not a good conparitor. Coke is not a result of a pH "crash" At steady state Coke is at 4 tops, I would surmise.
All the buffering does is slows the delta so it has less absorption capacity. It is less forgiving without said buffer, but it does not mean that it is unstable, just less stable.

[fresh_lynny]

Originally Posted by Hoppy

Edward's original post on APC was intended to make us understand that it is very high CO2 levels that kill fish, not very low pH, which results from the high CO2. And, if you accept that, then avoiding a "pH crash" should not be a concern, but going too high on CO2 without careful monitoring to be able to quickly drop the CO2 back down when the fish don't look so well, should be our concern. He even added that he had dropped the pH of a low pH tank still further using peat, down to about pH3 as I recall, without the fish showing any problems. This led me and others to conclude that messing around with baking soda to "avoid a pH crash" was not a useful activity. But, we have all said that you just cannot jack up the CO2 level, go off to work and return in the evening, unless you have no problem with losing the fish.

That is my point. This is true as low pH is not the problem, unless you have snails critters without exoskeleton, i.e. shrimp. More of the issue is the delta of pH at an accelerated rate. This is what will be detrimental to fish, not a low pH as a constant. The relationship of KH/pH and CO2 presence is harder to correlate at a low kH because of measurability with common instrumentation, those that we use in the hobby....i.e....crappy test kits with color indicators and regular pH probes.

[Betowess]

Originally Posted by plantbrain

Something not often done when reports of fish from GH= 0, KH= 0 in the Amazon rainforest, they use the normal probes, not the specialized ones for purer water.

Regards,
Tom Barr

Thanks for the input Tom. One question here. Are you saying that perhaps these "GH=0, KH=0 in the Amazon rainforest" are inaccurate, and that there is possibly higher carbonic and general hardness, or what? TIA

[Betowess]

Originally Posted by Raul-7

I remember reading over an experiment where soft water Characins were kept in water with a pH of 5 all the way down to pH 2, and survived. Sure, some Blackwater species thrive in low kH/pH water, but others will suffer - namely those of you who keep Rainbowfish; they have shorter lifespans in acidic water.

But many of these fish have been bred in captivity for so long that a lot of the general habitat qualities are suspect. And many of the desired parms are really related to breeding, rather than their ability to thrive or at least stay healthy in a planted tank. I for one don't plan on taking my tank below pH 6.0 and KH of 2 for my Rainbows.

[Wö£fëñxXx]

There are several factors involved with this so called pH crash which I actually attribute to C02
poisoning or oxygen depletion.

To try and help the general understanding of what I know of what is going on in the water of
these acidic tanks, streams and rivers I will copy and paste some information I have found viable
in growing weeds and fish in acidic condition's.

Biochemical Oxygen Demand, or BOD, is a measure of the quantity of oxygen consumed by
microorganisms during the decomposition of organic matter. BOD is the most commonly used
parameter for determining the oxygen demand on the receiving water of a municipal or industrial
discharge. BOD can also be used to evaluate the efficiency of treatment processes, and is an
indirect measure of biodegradable organic compounds in water.

Imagine a leaf falling into a stream. The leaf, which is composed of organic matter, is readily
degraded by a variety of microorganisms inhabiting the stream. Aerobic (oxygen requiring)
bacteria and fungi use oxygen as they break down the components of the leaf into simpler, more
stable end products such as carbon dioxide, water, phosphate and nitrate. As oxygen is
consumed by the organisms, the level of dissolved oxygen in the stream begins to decrease
Water can hold only a limited supply of dissolved oxygen and it comes from only two sourcesdiffusion
from the atmosphere at the air/water interface, and as a byproduct of photosynthesis.
Photosynthetic organisms, such as plants and algae, produce oxygen when there is a sufficient
light source. During times of insufficient light, these same organisms consume oxygen. These
organisms are responsible for the diurnal (daily) cycle of dissolved oxygen levels in lakes and
streams.

If elevated levels of BOD lower the concentration of dissolved oxygen in a water body, there is a
potential for profound effects on the water body itself, and the resident aquatic life. When the
dissolved oxygen concentration falls below 5 milligrams per liter (mg/l), species intolerant of low
oxygen levels become stressed. The lower the oxygen concentration, the greater the stress.
Eventually, species sensitive to low dissolved oxygen levels are replaced by species that are
more tolerant of adverse conditions, significantly reducing the diversity of aquatic life in a given
body of water. If dissolved oxygen levels fall below 2 mg/l for more than even a few hours, fish
kills can result. At levels below 1 mg/l, anaerobic bacteria (which live in habitats devoid of
oxygen) replace the aerobic bacteria. As the anaerobic bacteria break down organic matter,
foulsmelling hydrogen sulfide can be produced.

BOD is typically divided into two parts- carbonaceous oxygen demand and nitrogenous oxygen
demand. Carbonaceous biochemical oxygen demand (CBOD) is the result of the breakdown of
organic molecules such a cellulose and sugars into carbon dioxide and water. Nitrogenous
oxygen demand is the result of the breakdown of proteins. Proteins contain sugars linked to
nitrogen. After the nitrogen is "broken off" a sugar molecule, it is usually in the form of ammonia,
which is readily converted to nitrate in the environment. The conversion of ammonia to nitrate
requires more than four times the amount of oxygen as the conversion of an equal amount of
sugar to carbon dioxide and water.

When nutrients such as nitrate and phosphate are released into the water, growth of aquatic
plants is stimulated. Eventually, the increase in plant growth leads to an increase in plant decay
and a greater "swing" in the diurnal dissolved oxygen level. The result is an increase in microbial
populations, higher levels of BOD, and increased oxygen demand from the photosynthetic
organisms during the dark hours. This results in a reduction in dissolved oxygen concentrations,
especially during the early morning hours just before dawn.
In addition to natural sources of BOD, such as leaf fall from vegetation near the water's edge,
aquatic plants, and drainage from organically rich areas like swamps and bogs, there are also
anthropogenic (human) sources of organic matter. If these sources have identifiable points of
discharge, they are called point sources. The major point sources, which may contribute high
levels of BOD, include wastewater treatment facilities, pulp and paper mills, and meat and food
processing plants.

Organic matter also comes from sources that are not easily identifiable, known as nonpoint
sources. Typical nonpoint sources include agricultural runoff, urban runoff, and livestock
operations. Both point and nonpoint sources can contribute significantly to the oxygen demand in
a lake or stream if not properly regulated and controlled.

Performing the test for BOD requires significant time and commitment for preparation and
analysis. The entire process requires five days, with data collection and evaluation occurring on
the last day. Samples are initially seeded with microorganisms and saturated with oxygen (Some
samples, such as those from sanitary wastewater treatment plants, contain natural populations of
microorganisms and do not need to be seeded.). The sample is placed in an environment suitable
for bacterial growth (an incubator at 20o Celsius with no light source to eliminate the possibility of
photosynthesis). Conditions are designed so that oxygen will be consumed by the
microorganisms. Quality controls, standards and dilutions are also run to test for accuracy and
precision. The difference in initial DO readings (prior to incubation) and final DO readings (after 5
days of incubation) is used to determine the initial BOD concentration of the sample. This is
referred to as a BOD5 measurement. Similarly, carbonaceous biochemical oxygen test
performed using a 5-day incubation is referred to as a CBOD5 test.
http://www.deq.state.mi.us/documents...ygenDemand.pdf

Fish waste, excess food and even filter media play a vital role in the success or failure of this
environment. But ultimately it is the lack of oxygen that kills fauna, very high levels of C02 can do
this also obviously, but with high levels of C02 you also get lower levels of oxygen, so the proper
amount of surface agitation is vital.

High quality filter and media plays a vital role in this environment also because it helps control
nitrate, nitrite and ammonia..nitrate is also a form of acid, nitric acid.

BIOLOGICAL FILTRATION

It is no exaggeration to say that the condition of an aquarium depends very much on the performance
of its biological filter. When the filter's micro-organisms are thriving, the water will be crystal
clear and there is no algae growth.

The chemical reaction that expresses the oxidation process carried out by the nitrobacteria which
converts harmful ammonia into harmless nitrate is NH3; NO2; NO3. The bacteria that converts ammonia
(NH3) into nitrite (NO2) is called Nitrosomonas, and the bacteria that converts that into nitrate
(NO3) is called Nitrobactor. Research shown that the remaining nitrate is about 70 times less toxic
than nitrite, but if enough accumulates in the water it canstill be harmful. Therefore, it is always
necessary to frequently change the aquarium water even when using a top-of-the-line filter.

So we need good filters and media, lots of oxygen or surface agitation, but not to the degree that we
degrade our level of C02 content....which will be evident by algae growth, fish gasping and or poor
plant health based on the amount of light over the tank, and keeping the tank clean and free from excess
organic's, dead floating, rotting plant matter, and frequent water change's.

It is an environmental thing.

[mrbelvedere]

Originally Posted by fresh_newby

Coke is not highly acidic just becuse of CO2...It has acid as an ingredient in addition to carbonation <CO2>. Release of CO2 makes it more basic. Our tanks are not under the same pressure as Coke is, nor anything that is carbonated and remains carbonated. This is not a good conparitor. Coke is not a result of a pH "crash" At steady state Coke is at 4 tops, I would surmise.
All the buffering does is slows the delta so it has less absorption capacity. It is less forgiving without said buffer, but it does not mean that it is unstable, just less stable.

Active ingredient...phosphoric acid......very powerful...coke will dissolve a steak in 3 days......I did it for a school cience project.....

[Daniel*Swords]

I myself wouldn't be so worried about the low pH level than of the possible fluctuations of pH during the day. At least in Walstadt's book she describes how plants' photosynthesis and the consumed CO2 can up the pH a lot when there the alkalinity is low. Maybe this is not a problem with the high tech tanks and CO2 injection with pH controller but what about DIY systems and such? No problem?

Quoting from the book (p. 92):
"At an acidic pH of 5 and below, most of the water's [dissolved inorganic carbon] is CO2. At pH 6.5 the water contains about equal amounts of CO2 and bicarbonate, while at ph 8.5, almost allof the CO2 has converted to bicarbonates."

[fresh_lynny]

Originally Posted by mrbelvedere

Active ingredient...phosphoric acid......very powerful...coke will dissolve a steak in 3 days......I did it for a school cience project.....

Yes I clean my battery with it...That is my point. It is not the CO2 causing its highly acidic pH, it is added acid. So Coke is not a good representation of a "pH crash" which was the argument made. Just because it is carbonted doesn't mean it can be used as a comparitor.

[Brilliant]

Originally Posted by Wö£fëñxXx

I hope this helps all, at least some with their acidic endeavor's
I have enjoyed reading the response of all that have post so far, let it continue that we may grow in knowledge

Yah it helped. Thank you.
I looked to co2 to get my low pH habitat regardless of kh or gh, which are also on the low end of the scale. co2 is what led me to the planted tank.

So the debate here is that co2 will crash the pH in a 0-2KH environment?
Sorry for being a little slow.
Or is it that the lower the KH the lower the co2 you need to inject?

If pressurized co2 and 0-2 KH means pH crash exactly how long is this going to take? Ive been running for at least 3 months like this.

More questions...since my KH is nil and low GH does my Milwaukee pH51 handheld pH meter even work? accurate? I calibrate it often...does this even matter?