Alkalinity vs. ph. vs hardness???

luluvontepes

can someone please explain the relationship between total alkalinity and ph? my ph is high (7.3 in 10 gal tank and 8.2 in 3.5 gal tank; ph down ordered and arriving tomorrow).
my total alkalinity is at 40ppm in both tanks. why? according the the test strip this is low. also my hardness in a little high at 120ppm. i failed chemistry in high school, so i dont understand any of this. i have the nitrogen cycle down (how to monitor and help it) but still dont actually understand it. everything ive read says ph, alkalinity, and hardness are related. please help.
 

luluvontepes

Hi,
40ppm KH (2-3 degrees), and pH of 7.3 sounds about right

Here's a couple of threads that might help explain the relationships

GH, KH, and pH | pH Forum | 75315

https://www.fishlore.com/aquariumfishforum/threads/understanding-ph-kh-gh-in-home-aqauriums.113548/
the 7.3ppm in the 10 gal isnt too bad because ive added driftwood. before the wood, the ph was 8.2ppm. the 3.5 gal tank isnt big enough, and i cant get to store to buy it anyways, for a piece of driftwood. 3.5 gal tank has betta and horned nerite snail.

could the ph be high because of the black mountain seiryu stone? the lfs said it wouldnt raise the ph...
 
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Spudsssy

If you really need to adjust parameters I'd use natural methods... Peat, almond leaves, types of rocks etc... Better stability long term when done right.

I honestly would not worry about ph/kh unless your tap water is causing issues or you have fish that require highly soft or hard water. Most will adjust to ph around 6-8 once it's stable.
 
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Aprilbeingbasic

OK, I didnt fail chemistry so I will try explain this haha

Gh (general hardness) = amount of dissolved magnesium and calcium
KH (carbonate hardness) = amount of dissolved carbonates
TDS = total dissolved solutes, so amount of any type of mineral or chemical that conducts charge in the water
Generally the relationship between GH and KH is just that if you have a high GH you probably have a high KH, as often dissolved calcium start as calcium carbonate, so once dissolved you have a bunch of calcium and carbonates floating around.

Now first- what is pH? pH is the measurement of Hydrogen (H+) and hydroxide (OH-) ions in the water. when there are alot of H+ ions, the pH is below 7.0 and the water is acidic, when ph is above 7.0 the water has more OH- ions and is alkaline.

Now second- what is a buffer? a buffer is any chemical in water that resists change in pH. so you can have acidic buffers- chemicals that resist change in pH to keep it below 7.0. And alkaline buffers- chemicals that resist change in pH above 7.0. how do they do this? By reacting with H+ and OH+ ions. carbonate is an ALKALINE buffer.

So now lets look at carbonate- carbonate has the chemical sign CO3(-2), it is able to react with H+ (the thing that makes water acidic) and turn into HCO3- and H2CO3. When it does this (kind of eats up H+ ions) it stop the H+ ions staying in the water to make it acidic, so as a result it stops the water going below pH 7.0.

When you have lots of CO3(-2) ions in your water (so you have a high KH) those CO3(-2) will actually reacted with water (H2O) to turn into HCO3- and OH- (remember OH makes water alkaline) this kind of happens, then unhappens, but because its happening all the time, if you have heaps of CO3(-2) doing this then at any time you are going to have lots of OH- ions floating around, making your water alkaline.

this concept is also why ammonia is less toxic at acidic pH. NH3 is toxic to fish, but if your water has spare H+ (acidic) ions floating around NH3 turns into NH4+, which is not as toxic, but in alkaline water there is no H+ ions floating around so less NH3 turns to NH4+.

dunno if this helps haha I just felt like giving a science lesson
 
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GlennO

could the ph be high because of the black mountain seiryu stone? the lfs said it wouldnt raise the ph...

Yes it can raise pH. Those white steaks in the rock are calcite veins.
 
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luluvontepes

OK, I didnt fail chemistry so I will try explain this haha

Gh (general hardness) = amount of dissolved magnesium and calcium
KH (carbonate hardness) = amount of dissolved carbonates
TDS = total dissolved solutes, so amount of any type of mineral or chemical that conducts charge in the water
Generally the relationship between GH and KH is just that if you have a high GH you probably have a high KH, as often dissolved calcium start as calcium carbonate, so once dissolved you have a bunch of calcium and carbonates floating around.

Now first- what is pH? pH is the measurement of Hydrogen (H+) and hydroxide (OH-) ions in the water. when there are alot of H+ ions, the pH is below 7.0 and the water is acidic, when ph is above 7.0 the water has more OH- ions and is alkaline.

Now second- what is a buffer? a buffer is any chemical in water that resists change in pH. so you can have acidic buffers- chemicals that resist change in pH to keep it below 7.0. And alkaline buffers- chemicals that resist change in pH above 7.0. how do they do this? By reacting with H+ and OH+ ions. carbonate is an ALKALINE buffer.

So now lets look at carbonate- carbonate has the chemical sign CO3(-2), it is able to react with H+ (the thing that makes water acidic) and turn into HCO3- and H2CO3. When it does this (kind of eats up H+ ions) it stop the H+ ions staying in the water to make it acidic, so as a result it stops the water going below pH 7.0.

When you have lots of CO3(-2) ions in your water (so you have a high KH) those CO3(-2) will actually reacted with water (H2O) to turn into HCO3- and OH- (remember OH makes water alkaline) this kind of happens, then unhappens, but because its happening all the time, if you have heaps of CO3(-2) doing this then at any time you are going to have lots of OH- ions floating around, making your water alkaline.

this concept is also why ammonia is less toxic at acidic pH. NH3 is toxic to fish, but if your water has spare H+ (acidic) ions floating around NH3 turns into NH4+, which is not as toxic, but in alkaline water there is no H+ ions floating around so less NH3 turns to NH4+.

dunno if this helps haha I just felt like giving a science lesson
id love to say i understood any of that but after reading it 3 times it still makes no sense.... ugh. but what i think you are saying is because the alkalinity is low the ph wont stay as stable? and the lower the ph the quicker nitrite changes to nitrate? im thinking thats what i read...
how do i soften water?
 
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Aprilbeingbasic

id love to say i understood any of that but after reading it 3 times it still makes no sense.... ugh. but what i think you are saying is because the alkalinity is low the ph wont stay as stable? and the lower the ph the quicker nitrite changes to nitrate? im thinking thats what i read...
how do i soften water?
Aaah no. Sorry. Not at all what I meant.
 
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