PH low

[Fiori]

Steelhealr - I'm impressed You remember much more chemistry than my decaying old brain. Well I least I understood what you were writing

 

[steelhealr]

LOl....thanks Fiori...don't give me too much credit. I was a biochem major in college and an MD. Now if you asked me how to drill holes in an aquarium or setup a marine tank....FORGET IT....lolol That's why I'm posting here too...to get help. Good luck. SH

 

[Fiori]

err - now I'm feeling totally incompetent - cos I can't do those things either

Thanks to everybody who replied - my pH is now at 6.6 and sitting steady - fingers crossed

 

[slimecoat]

Alkalinity is is the ability of a solution to resist a pH change with the addition of an acid.

The text I quoted quite clearly is using dH per General Hardness as a measure of buffering capacity.

It doesn't help when people (not you, but the web page you quoted) use terms differently. I was taught that alkalinity was the opposite of acidity, i.e. the other end of the pH scale. As such, I don't see how it can be a measure of buffering capacity

Thanks for the input

 

[slimecoat]

Hi...from basic chemistry, acids are usually proton (hydrogen ion) donors, bases are 'acceptors. BiCarbonate, HC03 -, accepts hydrogen ions and therefore is a base. A buffer helps resist changes in pH by either absorbing or donating a hydrogen ion. CaCarbonate, when dissolved, provides the carbonate anion which can accept 2 hydrogen ions. So....if you have a high kH, ie, buffering capacity, and your tank tends towards acidity, the carbonate ion will pick up the acid (hydrogen ion) and convert to C02 and H20. pH will be stable until all buffering capacitiy is used up.Hence, stabilizing your tank from rapid pH swings.gH measurements reflect the amount of cation in the water, or Calcium and magnesium. Hope this helps (sheesh...my chem prof would be proud). SH

Great explanation, and as CaCO3 is the buffer that would make GH the better measurement, as the text I quoted said.

 

[reg2k2]

Alkalinity is the measure of buffering.
Alkaline is the opposite of acidic.
Easy to confuse, but most articles I've read make a point of noting this.

My KH from tap = 0, and I use crushed coral to remedy it. Not heard of it losing its ability to buffer (nor experienced this). Fiori, if your only complaint w/ the coral is the looks of it, don't add it to the gravel----add it to the filter. IME it doesn't require a lot, maybe a handful. Brings my KH to 3deg.--below the recommended minimum (4-5deg), but keeps my tank stable. The first time I replaced the coral (or added to it) was after a year. Although, I'm guessing it would bring your pH above 6.6...mine's been at 7.0 for the most part.

So, wouldn't it be GH not kH that indicates the water had buffering capacity to avoid unstable pH ?

No. "..Because softer water [usually] has less buffering capacity [KH!]...is subject to pH crashes."
GH, as far as I know, may become a concern if you're breeding fish or keep shrimp, but in relation to pH crash, it's definitely the KH you want to look at.

I can't answer any relation betw. GH and CaCO3 (no head for chemistry here), but I did read that alkalinity can be measured either in dH or ppm (of CaCO3).

And, dH = degrees hardness, specifically German degrees of hardness. So, you could say 4dKH, or 8dGH.

 

[steelhealr]

Alkalinity is is the ability of a solution to resist a pH change with the addition of an acid.

The text I quoted quite clearly is using dH per General Hardness as a measure of buffering capacity.

It doesn't help when people (not you, but the web page you quoted) use terms differently. I was taught that alkalinity was the opposite of acidity, i.e. the other end of the pH scale. As such, I don't see how it can be a measure of buffering capacity

Buffering works both ways. Back to chem....if you have a solution that is well buffered....with NaBicarb or CaCarbonate..it will resist changes when either acid or a base is added. Eg, if you overfeed and build up acids...or....excess hydrogen ions, H+, the bicarbonate will pick up and convert to C02 and H20, ie, 'resists a change to acidity, hence, stable pH (at least for awhile). That same liquid, if base is added , will resist becoming alkaline. Hydroxy ions or organic bases (remember above that bases are generally hydrogen ion acceptors) will either combine with dissoved calcium, or, a hydrogen ion can come off the bicarbonate leaving carbonate:

Eg....buffered aquarium with Na+ and HCO3-
fish poop and too much TetraMin and crisps, etc......acids....H+

H+ combines with HCO3-...forms H2CO3 which forms H2O and CO2....buffering

Remember the bad effect or opposite 'buffering' if you are slow to do water changes and overfeed? Ammonia builds up ...NH3. If the tank becomes acidic, ammonia is a base, remember? So ammonia picks up a hydrogen ion, H+ and becomes NH4+, ammonium ion. The latter is not as toxic to fish as ammonia is. Then, you realize that you are over due for a water change. Like my tap water, you do a large water change with a pH of 7.2 (alkaline as slimecoat says above). This alkalinity, whether it be bicarbonate in your water or carbonate ion, drags that hydrogen ion off the ammonium ion and suddenly your fish are exposed to large amounts of deadly ammonia...er...unbuffering in a sense. Floaters if you are not careful. SH

 

[slimecoat]

Alkalinity is the measure of buffering.
Alkaline is the opposite of acidic.
Easy to confuse, but most articles I've read make a point of noting this.

My KH from tap = 0, and I use crushed coral to remedy it. Not heard of it losing its ability to buffer (nor experienced this). Fiori, if your only complaint w/ the coral is the looks of it, don't add it to the gravel----add it to the filter. IME it doesn't require a lot, maybe a handful. Brings my KH to 3deg.--below the recommended minimum (4-5deg), but keeps my tank stable. The first time I replaced the coral (or added to it) was after a year. Although, I'm guessing it would bring your pH above 6.6...mine's been at 7.0 for the most part.

So, wouldn't it be GH not kH that indicates the water had buffering capacity to avoid unstable pH ?

No. "..Because softer water [usually] has less buffering capacity [KH!]...is subject to pH crashes."
GH, as far as I know, may become a concern if you're breeding fish or keep shrimp, but in relation to pH crash, it's definitely the KH you want to look at.

I can't answer any relation betw. GH and CaCO3 (no head for chemistry here), but I did read that alkalinity can be measured either in dH or ppm (of CaCO3).

And, dH = degrees hardness, specifically German degrees of hardness. So, you could say 4dKH, or 8dGH.

I disagree on basic English useage of suffixes

Alkaline is the opposite of acidic (adjectives)
Alkalinity is the opposite of acidity, it's just a different form of the above (state of being alkaline or acidic))

Here's a quote from this web site
http/fish.mongabay.com/chemistry.htm

"PH

The pH scale is a scale which is used to measure the acidity or alkalinity of a substance."

So pH measures alkalinity according to this

However here... http/bcn.boulder.co.us/basin/data/NUTRIENTS/info/Alk.html

it says.
"Alkalinity does not refer to pH, but instead refers to the ability of water to resist change in pH."

a contradiction. No wonder I am having trouble.

Yet another site refers to 'Total Alkalinity'. Is this the correct name for what you call Alkalinity, but what my test kit, and that first web site, calls one extreme of the pH scale?

You mention alkalinity can be measure in dH, but that is unit for general hardness GH.. So we are back to GH being a measure of buffering capacity, where I started.

 

[slimecoat]

Folks this is a minefield, and I think I will have to give up.

The experts disagree (from http/www.advancedaquarist.com/issues/feb.../chemistry.htm)
"
Finally there is the German term dKH (degrees of carbonate hardness), or just KH (carbonate hardness).Strictly speaking, it is the same as the carbonate alkalinity (AC in equation 8). Unfortunately, it is a very confusing term, as it has nothing to do with hardness. Further, it has been corrupted by the marine aquarium hobby to mean the same as total alkalinity, and every test kit that tests for dKH with a single titration is giving total alkalinity. The only kit that I am aware of that even makes a distinction between carbonate alkalinity and total alkalinity is one of the Seachem kits (Reef Status: Magnesium, Carbonate, & Borate) and it thankfully doesn’t use the term dKH at all. Consequently, most hobbyists should think of dKH as simply another measure of total alkalinity. The results obtained with such a kit (dKH) can be divided by 2.8 to yield the alkalinity in meq/L."

This page mentions even other definitions of alkalinity and GH doesn't even get mentioned here.

Mere mortals have no chance....

 

[steelhealr]

Alkalinity is the measure of buffering.
Alkaline is the opposite of acidic.
Easy to confuse, but most articles I've read make a point of noting this.

My KH from tap = 0, and I use crushed coral to remedy it.  Not heard of it losing its ability to buffer (nor experienced this).  Fiori, if your only complaint w/ the coral is the looks of it, don't add it to the gravel----add it to the filter. IME it doesn't require a lot, maybe a handful.  Brings my KH to 3deg.--below the recommended minimum (4-5deg), but keeps my tank stable.  The first time I replaced the coral (or added to it) was after a year.  Although, I'm guessing it would bring your pH above 6.6...mine's been at 7.0 for the most part.  

So, wouldn't it be GH not kH that indicates the water had buffering capacity to avoid unstable pH ?

No. "..Because softer water [usually] has less buffering capacity [KH!]...is subject to pH crashes."
GH, as far as I know, may become a concern if you're breeding fish or keep shrimp, but in relation to pH crash, it's definitely the KH you want to look at.

I can't answer any relation betw. GH and CaCO3 (no head for chemistry here), but I did read that alkalinity can be measured either in dH or ppm (of CaCO3).

And, dH = degrees hardness, specifically German degrees of hardness. So, you could say 4dKH, or 8dGH.

I disagree on basic English useage of suffixes

Alkaline is the opposite of acidic (adjectives)
Alkalinity is the opposite of acidity, it's just a different form of the above (state of being alkaline or acidic))

Here's a quote from this web site
http/fish.mongabay.com/chemistry.htm

"PH

The pH scale is a scale which is used to measure the acidity or alkalinity of a substance."

So pH measures alkalinity according to this

However here... http/bcn.boulder.co.us/basin/data/NUTRIENTS/info/Alk.html

it says.
"Alkalinity does not refer to pH, but instead refers to the ability of water to resist change in pH."

a contradiction. No wonder I am having trouble.

Yet another site refers to 'Total Alkalinity'. Is this the correct name for what you call Alkalinity, but what my test kit, and that first web site, calls one extreme of the pH scale?

You mention alkalinity can be measure in dH, but that is unit for general hardness GH.. So we are back to GH being a measure of buffering capacity, where I started.

Slimecoat.....here is an excellent example of how NOT to trust everything on the web. Here is a quote from one of the website links you gave above:

Alkalinity is a measure of the buffering capacity of water, or the capacity of bases to neutralize acids.

This is FALSE....alkalinity is a measure of the buffereing capacity of alkaline water to buffer against an acid...or..the overall base content of water containing a base. The first part of the line, alone, is false. SH

Another example, lets say you have aquarium water with "100 NaBicarb" ions. This solution would be alkaline. You would have to add 100 H+ ions before that solution would show any changes in pH to show acidity. Hence, an alkaline solutions buffering capability.

If you wanted your aquarium water to remain at 6.5, a slightly acidic condition, you would use acidity, or hydrogen ions (or other organic acid), to buffer against a change towards alkalinity. SH

 

[slimecoat]

If you wanted your aquarium water to remain at 6.5, a slightly acidic condition, you would use acidity, or hydrogen ions (or other organic acid), to buffer against a change towards alkalinity. SH

Actually, that's just what I want. So which organic acid should be used in a fish tank to stop/buffer the water against pH drifting high?

Would the use of this acid conflict with the use of coral to raise the GH ? (I still don't understand the statements I have read that soft water might let pH wander. That implies a relationship between GH and buffering)

 

[steelhealr]

Well...from what I've read and learned from people here, and what I've learned in science (and all feel free to correct me):
1) Sodium Bicarb will improve buffering without increasing gH and will slightly increase the pH. Since you have to add it to the aquarium, you have to be very careful not to make rapid pH changes. I believe recommendations say not to change it more than 1/2 pH unit per day. Forum member Def left parameters here that he used successfully. I went slower and brought my kH up one unit, but, in so doing, my pH now seems very stable.
2) Adding coral shell will do this more gradually, but, since it contains calcium, will also bring up your gH thus hardening the water.

My experience. My tap was pH 7.2,gH 2, kH 2. Aquarium water same with pH 7.0 usually sliding to 6.5/6.6 at the end of the week. During my 25% water change, I added 1/2 tsp NaBicarb and repeated the next day. All my fish are doing great and my new parameters are pH7.0, gH2, kH 4. Good luck. SH

 

[slimecoat]

Well...from what I've read and learned from people here, and what I've learned in science (and all feel free to correct me):
1) Sodium Bicarb will improve buffering without increasing gH and will slightly increase the pH. Since you have to add it to the aquarium, you have to be very careful not to make rapid pH changes. I believe recommendations say not to change it more than 1/2 pH unit per day. Forum member Def left parameters here that he used successfully. I went slower and brought my kH up one unit, but, in so doing, my pH now seems very stable.
2) Adding coral shell will do this more gradually, but, since it contains calcium, will also bring up your gH thus hardening the water.

My experience. My tap was pH 7.2,gH 2, kH 2. Aquarium water same with pH 7.0 usually sliding to 6.5/6.6 at the end of the week. During my 25% water change, I added 1/2 tsp NaBicarb and repeated the next day. All my fish are doing great and my new parameters are pH7.0, gH2, kH 4. Good luck. SH

The difference is that my pH is rising, not falling, and previous poster suggested an organic acid to contribute Hydrogen ions (which Sodium bicarb isn't going to do)

What's a suitable organic acid - vinegar, citric acid? What makes an acid, not just lower the pH, but stop at a desired point, and just buffer the solution there instead.

I guess the makers of Bullseye know.

 

[steelhealr]

Slimecoat....all buffers will be exhausted after awhile if there is continued exposure/addition of either the acid or base. Those people here who have water out of the tap with a good kH will always be 'rebuffering' their aquarium with their water changes. Although I added NaBicarb to my water, with a tap kH of 2, my buffering capacity will slide after awhile and I'm sure I may have to repeat what I did. Hence, I will be now regularly checking my kH. I think that if you are continually having a rising pH, most people would suggest peat added to the filter. I have no experience there. You might want to post a 'peat question'. Peat is an acidifier. I think it is unusual that you have a rising pH. Maybe your tap water is very alkaline and water changes bring it up. Good luck. SH

PS...I wouldn't add any of those to a tank...vinegar or citric acid. YIKES. SH

 

[slimecoat]

Slimecoat....all buffers will be exhausted after awhile if there is continued exposure/addition of either the acid or base. Those people here who have water out of the tap with a good kH will always be 'rebuffering' their aquarium with their water changes. Although I added NaBicarb to my water, with a tap kH of 2, my buffering capacity will slide after awhile and I'm sure I may have to repeat what I did. Hence, I will be now regularly checking my kH. I think that if you are continually having a rising pH, most people would suggest peat added to the filter. I have no experience there. You might want to post a 'peat question'. Peat is an acidifier. I think it is unusual that you have a rising pH. Maybe your tap water is very alkaline and water changes bring it up. Good luck. SH

PS...I wouldn't add any of those to a tank...vinegar or citric acid. YIKES. SH

But peat lowers hardness (GH). Can't see how it would contribute H+ ions.

It seems, from further reading, that bicarb and carbonate ions buffer in both directions.

" In most waters these bases are principally bicarbonate (HCO) ions and carbonate ions (CO32-). These ions are the buffers in water; that is they buffer the water against sudden changes in pH. They can do this by absorbing hydrogen ions when the water is acid and releasing them when the water becomes basic."

btw: I am fairly convinced people should be using the term 'Total Alkalinity' as opposed to alkalinity, when discussing buffering capability. Certainly that's what test strips for swimming pools call it.


(I know I said I was going to give up, but I keep getting drawn back to this I have the urge to know !)