Can sombody please give me a VERY basic explanation of the relationship between PH, alkalinity, and Calcium. I keep reading about it, but it's not sinking in. Kind of like how I can never remember my keys. The minute I put the book down, it slips right out of my mind.
relationship btw PH, ALK, & Calcium
- Thread starter LeslieS
- Start date
- Location
- Washington Heights, NY
Hey LeslieS,
Its complicated (and I might be wrong
) but I'll try. Corals use calcium and alkalinity to make up their calcium carbonate skeletons. Unlike calcium, alkalinity is made up of a bunch of things, but we worry mostly about bicarbonate and carbonate. Now corals take up calcium and bicarbonate but not carbonate. They convert the bicarbonate to carbonate and use both the carbonate and calcium to make the calcium carbonate.
At higher pH there is more carbonate than bicarbonate. One pH unit drop equates to a ten-fold decrease in carbonate to bicarbonate. So the lower the pH the easier for the coral to take up bicarbonate.
But at lower pH its harder for the coral to convert the bicarbonate to carbonate.
Turns out the natural pH of the ocean was just right.
Lastly pH and alk have a direct relationship. For a certain alk value there will be a pH value. That pH value will change depending on how much CO2 you have in your tank.
Hope this helps.
Its complicated (and I might be wrong
) but I'll try. Corals use calcium and alkalinity to make up their calcium carbonate skeletons. Unlike calcium, alkalinity is made up of a bunch of things, but we worry mostly about bicarbonate and carbonate. Now corals take up calcium and bicarbonate but not carbonate. They convert the bicarbonate to carbonate and use both the carbonate and calcium to make the calcium carbonate. At higher pH there is more carbonate than bicarbonate. One pH unit drop equates to a ten-fold decrease in carbonate to bicarbonate. So the lower the pH the easier for the coral to take up bicarbonate.
But at lower pH its harder for the coral to convert the bicarbonate to carbonate.
Turns out the natural pH of the ocean was just right.
Lastly pH and alk have a direct relationship. For a certain alk value there will be a pH value. That pH value will change depending on how much CO2 you have in your tank.
Hope this helps.
- Location
- Forest Hills
:splitspin that was confusing.:splitspin :biglaugh:
Leslie,
From one relative newb to another.
PH
At the very basic level PH is the acidity of the tank, with lower being more acidy. Your tank will naturally tend to get more acidic because of things like fish waste and various acids from the processes in your tank, the same thing happens in the ocean.
Alk
The primary thing that protects your PH from going down and melting all your fish :sgrin: is your alkalinity (otherwise known as the measurement of carbonate and bicarbonate in a reef tank), that why folks call it a buffer. Once your alk goes down, that buffer is gone and PH will start dropping as well (making the water more acidic). Alkalinity is used up by corals to build skeletons and so gets used up really fast in tank with a lot of colored sticks (sps). Therefore if your PH is low then you probably have a low alk problem likely because all of your greedy sps and coralline are eating it up to build skeletons!
Calcium
Calcium is also used by your corals to build skeletons. Calcium actually will precipitate out if your Alk gets too high, thereby preventing you from actually raising the amount dissolved in the water (so don't go all willy nilly adding a whole bunch of alk [like I did ]. Any calcium added when your Alk is too high will not dissolve, instead you will have a fine dust in the water (much like sugar in a cold drink). Although I like sugar in my iced tea, my corals don't get much use of calcium precipitate, they prefer it dissolved.
Obviously, you still need a constant level of Alk to protect your tank from the low PH acid reflux syndrome and to feed your corals and a constant level of calcium also to build strong muscular corals. The trick is to find the right balance.
Final note (I know you didn't ask but I had to say it!): Calcium absorption also is dependant on magnesium. Rarely, a tank will not have enough magnesium and will, again :irked: , be unable to absorb calcium (a lot like when you have high alk). It doesn't happen as often as people think it does but it can occur.
Hope that was straightforward! I sure had fun writing it.
E
From one relative newb to another.
PH
At the very basic level PH is the acidity of the tank, with lower being more acidy. Your tank will naturally tend to get more acidic because of things like fish waste and various acids from the processes in your tank, the same thing happens in the ocean.
Alk
The primary thing that protects your PH from going down and melting all your fish :sgrin: is your alkalinity (otherwise known as the measurement of carbonate and bicarbonate in a reef tank), that why folks call it a buffer. Once your alk goes down, that buffer is gone and PH will start dropping as well (making the water more acidic). Alkalinity is used up by corals to build skeletons and so gets used up really fast in tank with a lot of colored sticks (sps). Therefore if your PH is low then you probably have a low alk problem likely because all of your greedy sps and coralline are eating it up to build skeletons!
Calcium
Calcium is also used by your corals to build skeletons. Calcium actually will precipitate out if your Alk gets too high, thereby preventing you from actually raising the amount dissolved in the water (so don't go all willy nilly adding a whole bunch of alk [like I did
]. Any calcium added when your Alk is too high will not dissolve, instead you will have a fine dust in the water (much like sugar in a cold drink). Although I like sugar in my iced tea, my corals don't get much use of calcium precipitate, they prefer it dissolved.Obviously, you still need a constant level of Alk to protect your tank from the low PH acid reflux syndrome and to feed your corals and a constant level of calcium also to build strong muscular corals. The trick is to find the right balance.
Final note (I know you didn't ask but I had to say it!): Calcium absorption also is dependant on magnesium. Rarely, a tank will not have enough magnesium and will, again :irked: , be unable to absorb calcium (a lot like when you have high alk). It doesn't happen as often as people think it does but it can occur.
Hope that was straightforward! I sure had fun writing it.
E
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- Location
- Ossining, NY
Leslie, let's not forget about the importance Mg (Magnesium) plays in balancing Ca and Dkh (carbonate hardness)
If my memory serves me correctly, deanos has a great link to an article that sums it all up.
House
If my memory serves me correctly, deanos has a great link to an article that sums it all up.
House
- Location
- Flushing, NY
Leslie,
From one relative newb to another.
PH
At the very basic level PH is the acidity of the tank, with lower being more acidy. Your tank will naturally tend to get more acidic because of things like fish waste and various acids from the processes in your tank, the same thing happens in the ocean.
Alk
The primary thing that protects your PH from going down and melting all your fish :sgrin: is your alkalinity (otherwise known as the measurement of carbonate and bicarbonate in a reef tank), that why folks call it a buffer. Once your alk goes down, that buffer is gone and PH will start dropping as well (making the water more acidic). Alkalinity is also used up by corals to build skeletons and so gets used up really fast in tank with a lot of colored sticks (sps). Therefore if your PH is low then you probably have a low alk problem likely because all of your greedy sps and coralline are eating it up to build skeletons!
Calcium
Calcium is also used by your corals to build skeletons. Calcium actually will precipitate out if your Alk gets too high, thereby preventing you from actually raising the amount dissolved in the water (so don't go all willy nilly adding a whole bunch of alk [like I did
Obviously, you still need a constant level of Alk to protect your tank from the acid reflux syndrome and to feed your corals and a constant level of calcium also to build strong muscular corals. The trick is to find the right balance.
Final note (I know you didn't ask but I had to say it!): Calcium absorption also is dependant on magnesium Rarely, a tank will not have enough magnesium and will, again :irked: , be unable to dissolve calcium (a lot like when you have high alk). It doesn't happen as often as people think it does but it can occur.
Hope that was straightforward! I sure had fun writing it.
E
I knew alk and PH had a correlation, but I wasn't sure exactly. Based on that, it seems like the Alk is like the hardness of the water (KH) because the KH does the same thing. Correct me if I'm wrong.
How's this.... http://www.kipsreef.com/reeftankchemistry.htm
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I do, but it's just as confusing as this thread
OK, so 16 pages is a little more than VERY BASIC
All of the other explanations were great. Without them, I could not have even started on the 16 page "basic" explanation.
I think, I can get it to stick in my head now that ezee and kimoyo broke it down for me
Leslie,
Almost forgot a couple of things.
The reason many reefers use aragonite is because it helps control your PH/Alk. When the water gets acidic (low PH) it kindof melts aragonite releasing alk and calcium into the water. Automatic buffer! That is also one of the reasons the ocean doesn't experience drops in pH, it has a ton of natural buffers, like arag. Combined with water volume and other factors the the PH of the ocean is very steady.
When you are dosing be careful about dosing too quickly. You may find that one of your stats is low (alk or calc), try to refrain from speed correcting. I did that and lost some really nice clams :irked: from the alk swing. Raise the amount slowly.
Your PH is different at night when your lights are off so you want to dose as close to then as possible. If you start getting a lot of sps, etc. be careful because they will eat up your alk really fast and drop the level. T
Then it's lemon juice city.
You prob know this stuff already but I thought I should round out the conversation.
E
Almost forgot a couple of things.
The reason many reefers use aragonite is because it helps control your PH/Alk. When the water gets acidic (low PH) it kindof melts aragonite releasing alk and calcium into the water. Automatic buffer! That is also one of the reasons the ocean doesn't experience drops in pH, it has a ton of natural buffers, like arag. Combined with water volume and other factors the the PH of the ocean is very steady.
When you are dosing be careful about dosing too quickly. You may find that one of your stats is low (alk or calc), try to refrain from speed correcting. I did that and lost some really nice clams :irked: from the alk swing. Raise the amount slowly.
Your PH is different at night when your lights are off so you want to dose as close to then as possible. If you start getting a lot of sps, etc. be careful because they will eat up your alk really fast and drop the level. T
Then it's lemon juice city.
You prob know this stuff already but I thought I should round out the conversation.
E
- Location
- Washington Heights, NY
Unfortunately, if you pH got low enough to dissolve the sand to act as a buffer your corals would be dead. Also, the aragonite will release bound phosphate when its dissolved.
In our reef aquarium with water changes and skimming, we see the reverse of the buffering because of biological processes (bacterial, etc.) going on in the sandbed. Many have noticed a larger demand on alk with a sandbed than without.
Kimoyo,
I actually don't want to turn this into a thread that goes off topic, out of respect for Leslie's request. But to avoid any misunderstanding from our posts and to clarify, when I referred to low PH "kindof melting" the sand, I was not being literal. lol
I think the challenge of this thread was not to prove that anyone of us is master of the sciences associated with reefing by reading articles and regurgitating large words, but instead taking what we know and attempting to pass it along in a digestible format for a beginner.
It is a generally expressed opinion of many folks in the reefing community that aragonite is an excellent buffer for a marine tank or at least significantly better than silica based sand, which was the point of my post. I definitely do not want to complicte this thread by introducing BB vs DSB nuances into it.
Thanks for the additional info,
E
I actually don't want to turn this into a thread that goes off topic, out of respect for Leslie's request. But to avoid any misunderstanding from our posts and to clarify, when I referred to low PH "kindof melting" the sand, I was not being literal. lol
I think the challenge of this thread was not to prove that anyone of us is master of the sciences associated with reefing by reading articles and regurgitating large words, but instead taking what we know and attempting to pass it along in a digestible format for a beginner.
It is a generally expressed opinion of many folks in the reefing community that aragonite is an excellent buffer for a marine tank or at least significantly better than silica based sand, which was the point of my post. I definitely do not want to complicte this thread by introducing BB vs DSB nuances into it.
Thanks for the additional info,
E
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- Location
- Washington Heights, NY
E,
The point of my post is that aragonite doesn't buffer when its in the display because the pH doesn't get low enough for it to. This buffering is done by dissolving (melting). It's the same reason why calc reactors need to be at a lower pH, so they can dissolve the calcium carbonate (what sand is) and add it to the reef. I just did a search on RC in Randy's forum and found this post. I hadn't seen this before but since you feel I'm regurgitating large words I'll show you what Randy thinks.
This is important for new reefers to know so they don't have a false sense of security, hope it helps.
Paul,
I think there is a misunderstanding here. The focus of my response was not to belittle your post, I apologize if you took that personally, not sure why you felt I was talking about something you said in particular. I was merely stating what I saw as the point of the thread and addressing your rebutt by clarifying what I was talking about.
In referring to Randy's post, despite the fact that he makes a blanket claim that aragonite buffers nothing, the article he sources actually says this at the end, in the section titled:
Recommended Uses for Calcium Carbonate
So while I definitely acknowledge that Randy Holmes Farley is an undoubted expert and far more knowledgeable than either of us (with regard to marine tank chemisty), I would say that the source he uses actually recommends the use of aragonite sand in some situations (with corals) as an option to buffer.
However, if you feel that the statement made earlier is the end all be all to this topic, I respect your choice.
Great article by the way. Still can't understand half of what Randy says though, lol.
E
I think there is a misunderstanding here. The focus of my response was not to belittle your post, I apologize if you took that personally, not sure why you felt I was talking about something you said in particular. I was merely stating what I saw as the point of the thread and addressing your rebutt by clarifying what I was talking about.
In referring to Randy's post, despite the fact that he makes a blanket claim that aragonite buffers nothing, the article he sources actually says this at the end, in the section titled:
Recommended Uses for Calcium Carbonate
In a tank with a low calcification rate, such as one with few corals or with mostly slow-growing corals, you might even get away with this method alone. The cost associated with even the commercial products will be fairly low, and using Southdown sand will be almost nonexistent. Still, it may be adequate to maintain pH, alkalinity, and calcium in such situations. Moreover, it will never (or almost never) become unbalanced the way separate additions of calcium and alkalinity might become over time.
So while I definitely acknowledge that Randy Holmes Farley is an undoubted expert and far more knowledgeable than either of us (with regard to marine tank chemisty), I would say that the source he uses actually recommends the use of aragonite sand in some situations (with corals) as an option to buffer.
However, if you feel that the statement made earlier is the end all be all to this topic, I respect your choice.
Great article by the way. Still can't understand half of what Randy says though, lol.
E
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