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Water Mystery

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
I am not very good in chemistry....I even misspelled the word...lucky me we have auto correct. I have been collecting rain water to use with my dwarf tanks for about 6-8 months now.

I use a liquid test kit by API. Rain water readings are: pH reads around 6.4, KH less then 50 ppm, but the gH reads over 250ppm.

Tap water readings are pH 7.0-7.2 KH around 80ppm and HG over 240ppm.

As a test I used Seachems acid buffer and lowered all the readings except the GH that keeps showing above 240ppm.

I have two API kits, they are 4-5 years old. I used both kits to test the same water and got the same readings from all the API kits for all tests. But still I wonder if the GH test bottles are bad.

Like I said I am not good in water chemistry and how things work. I grasp soft & hard water and acid and alkaline water. My understanding is soft goes with acid water and hard goes with alkaline water. Obviously it is not always the case...why?
If anyone has the time and patience to give me a simple brief lesson I would appreciate it and what I can do to lower gh. Right now I use peat moss, but it only affects pH and kH.

Thanks

george
 

regani

Active Member
5 Year Member
Messages
429
Location
Brisbane, Australia
I'll try to give a simplified explanation. Bear with me if this gets a bit long....

The GH is a value for the concentration of calcium (Ca2+)in the water - there also are some other ions that contribute to GH, mainly magnesium, but for sake of simplicity we'll leave that aside.

All salts are made up of cations (carrying the positive charge) and anions (carrying the negative charge). The cations are usually metals such as iron (Fe3+), sodium (Na+), calcium (Ca2+) and many others. The The metal cations such as Ca do not directly affect the pH (there are some exceptions, but they are not important here).

The one cation that is responsible for acidity is the hydrogen cation (H+) and you can look at acids as 'salts' of hydrogen.
The other part of a salt are the anions, such as chloride, sulfate, carbonate or bicarbonate. These can sometimes have a strong effect on pH. The most important of these here are carbonate and bicarbonate as they make the water alkaline.

Making a solution alkaline basically means 'destroying' the H+ ions that are responsible for the pH. The more H+ you can get rid off the more alkaline the water becomes.

Now, let's look at an example of a water sample and what happens when we add acid to make it acidic or a base to make it alkaline.
Let's say we have a water sample that contains 5 calcium ions that make a GH of 5 and 2 bicarbonate ions (HCO3-) that push the pH to 8.

If we add a little bit of acid of a sample that contains bicarbonate, the following chemical reaction happens:

HCO3- + H+ ----> CO2 + H2O

The bicarbonate and the acid react with each other and they form carbon dioxide and water. Like many reactions in chemistry this one is reversible and if it goes the other way it describes how carbon dioxide dissolves in water. Note how the number of each type of atoms stays the same on each side of the equation (even if we wish we could, we can't create or destroy matter) they just change allegiance, so to speak.
But because the carbon dioxide is a gas and can can escape from the water sample in our experiment, suddenly the reaction can't go back anymore (no CO2 around).

Let's go back now to our original water sample with all the ions in it:
5 Ca2+ + 2 HCO3-
We have the calcium that makes up the hardness and the bicarbonate that makes it slightly alkaline. If we add some acid, say 3 H+, the following happens: The acid will react will all the bicarbonate until either one is completely consumed, so Keeping the number of each type of atoms the same on rack side of the equation, we end up with the following equation:

5Ca2+ + 2 HCO3- + 3H+ -----> 5 Ca2+ 2 CO2 + 2 H2O + H+

We don't have any bicarbonate left to make the water alkaline, instead we now have some H+ left over and the pH of our solution has dropped to 6. What we can also see is that the number of calcium ions has not been affected at all. If we test the GH of our solution it still is 5.
While we can change molecules made up of different atoms, such as the bicarbonate molecule, we cannot change the individual atoms - unless we throw them into a nuclear reactor or into the sun. As we cannot change the calcium atoms into something else, the only way to change the GH is to remove (or add) calcium ions. This can be done using ion exchange resins or natural ion exchangers such as peat (not all peats are crated equal though and some work much better than others).

I hope this makes the hardness/pH issue a bit clearer?
 

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
Thank you for the class Regani. Really helped!!!!!!!!!!
If I understand you....since my reading for pH and KH are good and the only reading I wish to lower is the GH, peat moss is the answer. (what type of peat do you use....what should I look for in a peat?).
Obviously, once I use the peat, the other readings will change too.
Out of curiosity what could be causing the GH to be so off with respect to the pH and KH readings, especially for the rain water.

george
 

regani

Active Member
5 Year Member
Messages
429
Location
Brisbane, Australia
The GH may come from running down concrete roof tiles or if the rain water is captured/stored in a concrete rain water tank.

The question which peat is best and the difference between peat and sphagnum moss has been discussed here before. I am not that familiar with the trade names in the US, so maybe someone else can jump in.
 

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
Thanks regani, I think i'll test both and see which gives me the best results. I have some D Filamentosus and I want to breed them.

g
 

slimbolen99

Active Member
5 Year Member
Messages
550
Location
Shawnee, KS
If your test kit is 4-5 years old, you should seriously consider replacing it; I'm no chemist either, but after about a year I start getting results on my liquid test kits that don't match reality.
 

gerald

Well-Known Member
5 Year Member
Messages
1,491
Location
Wake Forest NC, USA
Where does your tap water come from? If it's a city or county public water system they will usually have some basic chemical parameters posted online (annual water testing report), including hardness and alkalinity (in mg/L). Divide mg/L by 18 to get degrees KH or GH. Is the source from groundwater wells or lake/river water? Most natural waters in the Carolinas have GH and KH values fairly close to each other. Raleigh water (from Neuse River) has GH and KH both around 25 to 40 mg/L. So I'd be surprised if your GH is really that much higher than KH.
 

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
The report I found was dated 2012, so its not that old. Here are the readings
units MCL sys avg
pH SU n/a 7.2
Alkalinity Mg/l n/a 13
Posphates Mg/l n/a 0.7
Hardness Mg/l n/a 4
Our water comes from a lake.
The more I learn the more I am convinced my test kit is not good. thanks for the info gerald.

g
 

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
That WOW was unexpected...but kinda makes a little sense if that kit is bad. Until a few years ago I always had soft water with a pH 6.8-6.9, using the same kit I am using now. Last year the readings started changing I thought the water co. was doing something different to the water. I think its time to get big boys test meter. Any suggestions on one that will cover most basic water tests (pH, GH, KH and any other "H" known to man), that will not require a second mortgage?

Again thanks for all the help gerald, slimbolen99 and regani.

g
 

gerald

Well-Known Member
5 Year Member
Messages
1,491
Location
Wake Forest NC, USA
Cheap test kits are fine for fish keeping, but get kits with liquid reagents or dry tablets (like Hach) -- not the dip-sticks. There is no meter for hardness (GH) or alkalinity (KH) - these must be measured by chemical titration (add reagent until color change occurs). I have some 5+ yr old Aquarium Pharmaceuticals kits for GH and KH that still seem to work OK, although I rarely have need to use them anymore.
 

Mike Wise

Moderator
Staff member
5 Year Member
Messages
11,202
Location
Denver, Colorado, U.S.A.
I use a Hanna HI-98129 pH/e.c./tds/temp meter - $150. You'll also need to have calibration/electrode storage solutions, so expect the price for several years of testing to be around $200. Compared to chemical tests on multiple tanks it is less expensive in the long run.
 

georgedv

Member
5 Year Member
Messages
335
Location
South Carolina
My API kit is about 3 or 4 years old and I have some serious doubts in its GH measurements (actually I have two kits the other is over 5 years old). Measurements from both kits are roughly the same....but since the water from the tap should be soft????
I find something new to be safe.

Thanks Mike just checked it out on Amazon.

g
 

MickeM

Active Member
5 Year Member
Messages
441
Location
STOCKHOLM , SWEDEN
I'll try to give a simplified explanation. Bear with me if this gets a bit long....

The GH is a value for the concentration of calcium (Ca2+)in the water - there also are some other ions that contribute to GH, mainly magnesium, but for sake of simplicity we'll leave that aside.

All salts are made up of cations (carrying the positive charge) and anions (carrying the negative charge). The cations are usually metals such as iron (Fe3+), sodium (Na+), calcium (Ca2+) and many others. The The metal cations such as Ca do not directly affect the pH (there are some exceptions, but they are not important here).

The one cation that is responsible for acidity is the hydrogen cation (H+) and you can look at acids as 'salts' of hydrogen.
The other part of a salt are the anions, such as chloride, sulfate, carbonate or bicarbonate. These can sometimes have a strong effect on pH. The most important of these here are carbonate and bicarbonate as they make the water alkaline.

Making a solution alkaline basically means 'destroying' the H+ ions that are responsible for the pH. The more H+ you can get rid off the more alkaline the water becomes.

Now, let's look at an example of a water sample and what happens when we add acid to make it acidic or a base to make it alkaline.
Let's say we have a water sample that contains 5 calcium ions that make a GH of 5 and 2 bicarbonate ions (HCO3-) that push the pH to 8.

If we add a little bit of acid of a sample that contains bicarbonate, the following chemical reaction happens:

HCO3- + H+ ----> CO2 + H2O

The bicarbonate and the acid react with each other and they form carbon dioxide and water. Like many reactions in chemistry this one is reversible and if it goes the other way it describes how carbon dioxide dissolves in water. Note how the number of each type of atoms stays the same on each side of the equation (even if we wish we could, we can't create or destroy matter) they just change allegiance, so to speak.
But because the carbon dioxide is a gas and can can escape from the water sample in our experiment, suddenly the reaction can't go back anymore (no CO2 around).

Let's go back now to our original water sample with all the ions in it:
5 Ca2+ + 2 HCO3-
We have the calcium that makes up the hardness and the bicarbonate that makes it slightly alkaline. If we add some acid, say 3 H+, the following happens: The acid will react will all the bicarbonate until either one is completely consumed, so Keeping the number of each type of atoms the same on rack side of the equation, we end up with the following equation:

5Ca2+ + 2 HCO3- + 3H+ -----> 5 Ca2+ 2 CO2 + 2 H2O + H+

We don't have any bicarbonate left to make the water alkaline, instead we now have some H+ left over and the pH of our solution has dropped to 6. What we can also see is that the number of calcium ions has not been affected at all. If we test the GH of our solution it still is 5.
While we can change molecules made up of different atoms, such as the bicarbonate molecule, we cannot change the individual atoms - unless we throw them into a nuclear reactor or into the sun. As we cannot change the calcium atoms into something else, the only way to change the GH is to remove (or add) calcium ions. This can be done using ion exchange resins or natural ion exchangers such as peat (not all peats are crated equal though and some work much better than others).

I hope this makes the hardness/pH issue a bit clearer?


Hi regani + all,

Through the years of breeding many Apistos I have managed to get some really good results by cleaning a few (1-3) liters of the sand + change 5-20% of the water whenever I want to start the fishes(Apistos) to mate.
My conclusion is that the GH (KH)/TDS/Electric Conductivity drops a bit more when I remove some of the "rest products" in the sand compared to only changing some water..
I have never ever measured this, but it almost never fails.. I imagine that the total amount of GH/KH in the tank then must drop/get lower..!!??


What I really wonder is .. Does anybody know if new colonies of the growing cells of bacteria in the sand can absorb these chemicals in the volumes and rate, and maybe a few days later show changes of the water parameters??

I`ve been thinking of this "theory" for quite some time.. What made me think of it was this:

- Start of a major rain (water change) is said to start mating(many fishes) + the low GH/KH/EC in natural Apisto rivers.
- Low GH/KH "almost" always is recommended to guarantee success in breeding of Apistos. (Rainwater/Reversed osmosis)
- The repeated results of my method.. (if the females are ready/full of eggs)
- Reading in Dr. Yuri I. Sorokins book "Ecological Studies - Coral Reef Ecology" , Springer Verlag (Purchased in London 1994-95??!!:))

Would be really happy if someone have any info or research facts about this bacteria issue !!

cheers MickeM
 
Last edited:

regani

Active Member
5 Year Member
Messages
429
Location
Brisbane, Australia
If you have never measured when doing your changes, how do you know that the HH, KH, or TDS are dropping?
I am not saying your method isn't working, just wondering what makes you thing it has something to do with water values as opposed to e.g. disturbing territories or similar
 

MickeM

Active Member
5 Year Member
Messages
441
Location
STOCKHOLM , SWEDEN
If you have never measured when doing your changes, how do you know that the HH, KH, or TDS are dropping?
I am not saying your method isn't working, just wondering what makes you thing it has something to do with water values as opposed to e.g. disturbing territories or similar

Hi,

I do this (at earliest) after 2-3weeks or more.. never after only one week..(in new setups), so I can see that "restproducts" are following the water out of the tank.. as it usually do.

And I never change anything except removing water + some sand and put it back in the same free area, without moving anything in the tank. (never refurnishing anything)
Since I have not tested the water, I can not "prove" any changes as you say. But when one take out some concentrated substances/solutions out of closed system, I`m quite sure one changes the conditions of eventually further chemical bonds/reactions...
Some chemicals are obviously being removed when one looks in the bucket of water....!

The TDS or EC might not change (depends on the possibility of chem. bonding at this moment..the hours/days after changing) , but maybe the GH/KH will?? I really think so!! Would be interesting to know...
Have anyone been testing this ??

Or it might the small difference in temp, but I don`t think 1/10 new water can accomplish that effect!!??

/MickeM
 
Last edited:

MickeM

Active Member
5 Year Member
Messages
441
Location
STOCKHOLM , SWEDEN
BTW...There also must be some reasons why Water Managing(?) Companies often use/used sand filters in their cleaning/filter systems!!??
 
Last edited:

regani

Active Member
5 Year Member
Messages
429
Location
Brisbane, Australia
Well, the next time you do those changes you can measure before and after and let us know if anything changes.
To get as complete a picture as possible, you should test the water in the tank before and after the change as well as the water you are adding. As the drop tests tend to be a little variable at times, it is probably best to take at lest 3 water samples and test.
As you suggest that your changes affect GH and KH, you should test for those, probably also pH.
Any TDS/conductivity meter should be freshly calibrated for measurements. If you have you could also use a redox meter, which will give you additional information about further changes in the water. It'd be good to check temperature fluctuations as well, just to be sure.
 

dw1305

Well-Known Member
5 Year Member
Messages
2,755
Location
Wiltshire UK
Hi all,
BTW...There also must be some reasons why Water Managing(?) Companies often use/used sand filters in their cleaning/filter systems!!??
They are pretty effective as both mechanical and microbial filters. If you are space limited, or you need to process a lot of water, you can use a fluidised filter bed, but if you have more room you can just let the water flow through the sand bed under gravity. These BioSand or "slow sand bed" filters are pretty effective, don't have any moving parts and are a KISS solution to water purification <http://en.wikipedia.org/wiki/Slow_sand_filter>.

cheers Darrel
 

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