Alkalinity What is it?

[whatnot45]

Ok so... i have kept reeftanks for about 4 years now, and i am going trying to get a job at my lfs this summer (im 16) Any ways, So the guy who runs it told me to write him a couple paragraphs on Alkalinity, and its effects on reef tanks, (algae, corals, fish...) Honestly, i have never really botherd to worry about my tank's alkalinity before, and i have no idea what it is. Any help?

[Ninong]

Here ya go:

Calcium and Alkalinity

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH
http://reefkeeping.com/issues/2006-06/rhf/index.php

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

A Homemade Two-Part Calcium and Alkalinity Additive System
http://www.advancedaquarist.com/iss...il2004/chem.htm

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

How to Select a Calcium and Alkalinity Supplementation Scheme
http://www.advancedaquarist.com/issues/feb2003/chem.htm

Electronic Calcium Monitoring
http://reefkeeping.com/issues/2005-04/rhf/index.htm

Purity of Calcium Chloride
http://www.advancedaquarist.com/issues/mar2004/chem.htm

Calcium and Alkalinity Balance Issues
http://reefkeeping.com/issues/2002-...ature/index.htm

Calcium Carbonate as a Supplement (Aragamight; Liquid Reactor)
http://www.advancedaquarist.com/iss...ly2002/chem.htm

The Relationship Between Alkalinity and pH.
http://www.advancedaquarist.com/issues/may2002/chem.htm

The Chemical & Biochemical Mechanisms of Calcification in Corals
http://www.advancedaquarist.com/issues/apr2002/chem.htm

Calcium
http://www.advancedaquarist.com/2002/3/chemistry

What is Alkalinity
http://www.advancedaquarist.com/2002/2/chemistry

Happy reading!

:D

[whatnot45]

Isn't there like some simpler explanation that i might actually be able to understand?

[bertoni]

http://www.advancedaquarist.com/2002/2/chemistry

That article might help.

[Billybeau1]

<a href=showthread.php?s=&postid=9822200#post9822200 target=_blank>Originally posted</a> by whatnot45
Ok so... i have kept reeftanks for about 4 years now, and i am going trying to get a job at my lfs this summer (im 16) Any ways, So the guy who runs it told me to write him a couple paragraphs on Alkalinity, and its effects on reef tanks, (algae, corals, fish...) Honestly, i have never really botherd to worry about my tank's alkalinity before, and i have no idea what it is. Any help?

Thats because you have seahorse tanks. Do you have corals, inverts, hard to keep marine fish ?

The owner of the store obviously wants someone who can give good advice to his customers. You don't learn this stuff overnight. Seahorse tanks are not reef tanks.

You have a lot to learn about water chemistry and you are not going to learn it by a couple of posts. You should read many of the articles Ninong posted. This is how you learn. Read, Read, Read.

There are too many fish stores with uneducated employees giving bad advice.

I know your 16. Been there. My advice is to tell him you don't really understand alkalinity but you are studying it and you will get better with experience.

Don't ever pretend to know something that you don't. It never works in the long run.

[boxfishpooalot]

akalinity is the total amount of ions in water that contribute to ph.

There are lots of things in seawater that do-

-bicarbonate
-carbonate
-hydroxide
-borate

Here is a graph I made of the constitutes of alkalinity:

<a href="http://photobucket.com" target="_blank"><img src="http://i5.photobucket.com/albums/y178/salwaterfish123/totalalkalinity.bmp" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>

Of those 4, bicarbonate makes up the most of alkalinity. The rest only contribute slightly. The more Co2 in the water the lower the ph of your tank will become, and the less Co2 in the water the higher the ph will become. As the ph lowers the carbonate portion will change to more bicarbonate and less carbonate. Lowering ph. As Co2 leaves the water, the bicarbonate forms back to more carbonate and less bicarbonate.

Here is another graph I made. It shows what happens when ph rises, what happens to the constitues of alkalinity. In the first ph is 8.2. Natural seawater is usually at this ph.

<a href="http://photobucket.com" target="_blank"><img src="http://i5.photobucket.com/albums/y178/salwaterfish123/alkph8.bmp" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>

But as more Co2 leaves, the ph rises. And it shifts to more carbonate and less bicarbonate. Here ph is 8.6

<a href="http://photobucket.com" target="_blank"><img src="http://i5.photobucket.com/albums/y178/salwaterfish123/alh8.bmp" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>

If you were to remove most of the Co2 in the water, the ph would skyrocket. But the alkalinity has not changed at all just the ph of the water. Shown at ph 10.

<a href="http://photobucket.com" target="_blank"><img src="http://i5.photobucket.com/albums/y178/salwaterfish123/sdlfkjasdflkjsaklfjsalkj.bmp" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>

Here is 2 guys adding an acid and a base. This explains ph a little bit. A base in seawater would be bicarbonate, because its ph is above 7.

<a href="http://photobucket.com" target="_blank"><img src="http://i5.photobucket.com/albums/y178/salwaterfish123/ph_balance.gif" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>


Hope you learn somthin :)

[bertoni]

Well, technically, alkalinity is a measure not of pH, but more like the water's ability to resist changes in pH. The definition is the number of protons required to convert all the bicarbonate and carbonate to carbonic acid. Here's the equation:

TA = [HCO3-] + 2[CO3--] + [B(OH)4-] + [OH-] + [Si(OH)3O-] + [MgOH+] + [HPO4--] + 2[PO4---] - [H+]

[whatnot45]

<a href=showthread.php?s=&postid=9822839#post9822839 target=_blank>Originally posted</a> by Billybeau1
Thats because you have seahorse tanks. Do you have corals, inverts, hard to keep marine fish ?

The owner of the store obviously wants someone who can give good advice to his customers. You don't learn this stuff overnight. Seahorse tanks are not reef tanks.

You have a lot to learn about water chemistry and you are not going to learn it by a couple of posts. You should read many of the articles Ninong posted. This is how you learn. Read, Read, Read.

There are too many fish stores with uneducated employees giving bad advice.

I know your 16. Been there. My advice is to tell him you don't really understand alkalinity but you are studying it and you will get better with experience.

Don't ever pretend to know something that you don't. It never works in the long run.


I used to have 2 nano reefs before i converted them to seahorse tanks. My 29 gallon was an SPS/Clam tank, and my 5 gallon was a mushroom/softy tank... Im not compleatly new to this stuff. And I have known the guy for a while, and he knows that im not an expert.... any waysThanks for your help Now that i have a basic understanding ill try and tackle those articles.

[Boomer]

Ninong

You are going to make his head hurt, he is in HS :lol: I think Box did a great job for starts.

In short, Alkalinity is the ability to neutralize acids. So, if one had a pH of 8.3 an the alkalinity was 3 and some acid was added the pH will remain the same but the alkalinity will drop, say to 2. If there is even more acid added the alkalinity will drop even further. Once it hits zero the pH will drop like a rock. However, just so you know, if CO2 is added the pH will drop like a rock even if the is plenty of Alkalinity. The CO2 will combine with the carbonate CO3 and water H20 and makes 2 bicarbonates, which has a lower pH than CO3.

CO3 + CO2 + H2O --> 2HCO3

Notice the "H" in HCO3 and the H in pH means hydrogen and the more H there is the lower the pH, so the HCO3 will produce a lower pH. But the Alkalinity has not changed here, it just got convered from CO3 to HCO3. Both HCO3 and CO3 make up most of the alkalinity. And Alkalinty is the toal amount of these two for the most part and not their %

At a pH of 8. 3 the % of the two will be the same but the amount may be more or less.

Look at it his way. If we say 1 dollar is made up of 4 nickles (CO3) and 8 dimes(HCO3) an we then change it to 2 nickels(CO3) and 9 dimes(HCO3) for 1 dollar that is what CO2 does. Alk is like having 3 dollors with x and y nickels and dimes.

[whatnot45]

sweet thanks guys! (especially box and boomer) that really cleared most of my confusion up :)

[Mike O'Brien]

Here is one more for you.

Alkalinity is one of the most important parameters of a reef tank. What's strange about alkalinity is it's not as straight forward as something like calcium. Calcium is low, so we add calcium to the tank. That's easy. With alkalinity it's just a bit different. Alkalinity is not really something in the tank, you don't get a bottle of alkalinity and add some to your tank. There are several different chemicals in sea water that contribute to this. Here is the list.

HCO3- (bicarbonate) 89.8 %
CO3-- (carbonate) 6.7 %
B(OH)4- (borate) 2.9 %
SiO(OH)3- (silicate) 0.2 %
MgOH+ (magnesium monohydroxylate) 0.1 %
OH- (hydroxide) 0.1 %
HPO4-- and PO4--- (phosphate) 0.1 %

You'll notice that bicarbonate and carbonate make up the bulk of the chemical species that contribute to alkalinity. These are what we, as reef aquarists, are interested in. These are what corals use to produce their aragonite skeleton. Actually mainly bicarbonate is taken up by corals, but carbonate and bicarbonate can inter convert in seawater depending on pH. They are also used during photosynthesis by both symbiotic algae in corals and micro and macro algae in the tank as a carbon source.

Though there are all these things that make up the total alkalinity of the tank, obviously it's the coral building of the bicarbonate and carbonate that we are interested in. One definition for alkalinity is that it's a chemical property of the water to resist pH change upon the addition of acid. Even though resistance to pH drop is important we measure alkalinity to ensure that there is enough bicarbonate and carbonate in the water. but there may be a problem. You'll also notice that borate is third on the list. This is important because unlike bicarbonate and carbonate, borate is not used in calcification, but it may play a significant role in total alkalinity. Remember these numbers are for natural sea water. The numbers in artificial sea water can vary dramatically. Many salts have elevated borate levels to begin with, it helps to maintain pH. It's obviously helpful for fish only tanks where there is no emphasis on calcification, but in our reef tanks we don't really want any more of it than necessary. Keep an eye on the ingredients in the alkalinity buffers you use. For example a popular brand is Kent super buffer dKH, this additive contains a high percentage of borate. Lately they've come out with another additive called coral builder which is a bicarbonate carbonate mix and is much more suited to our use. When using such salts and additives you may end up with elevated borate, and with that comes diminished bicarbonate for a given alkalinity.

Alkalinity is closely tied to pH. In fact there is a direct linear rise in pH with a rise in alkalinity. other than alkalinity the only major contributor to the pH of the tank is the amount of CO2 in the water. So basically maintaining adequate alkalinity and keeping good gas exchange to the tank will ensure that the pH is within acceptable range. This is also the reason why one should not try to control the pH with the use of buffers. This is common advice that is frequently given to new aquarist's. Doing this does raise the pH, but in doing so it elevates the alkalinity too high. Low pH is almost always a gas exchange issue or an issue with excess CO2 in the house. So again don't try to control pH with the use of buffers.

Test kits measure alkalinity in three different units, ppm CaCo3 equivalents, meq/l and dKH.

50 ppm = 1 meq/l = 2.8 dKH.

Reef tank recommendations being

125-200 ppm , 2.5-4 meq/L, 7-11 dKH

An important thing to consider is the amount of alkalinity in the water compared to calcium. During calcification 50 ppm of alkalinity are consumed for every 20 ppm of calcium. So more than twice the amount of bicarbonate is used compared to calcium. Since recommended reef tank levels of bicarbonate are only 175 ppm alkalinity can drop extremely fast in relation to calcium. For this reason it is extremely important to test for and maintain adequate alkalinity in our tanks.

Happy Reefing.


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The ZooKeeper