For the new people and to help me catch any I've missed. How about a list of all the common Acronyms used around here.

Here's some I've caught so far:

Miscellaneous
WTB - Want To Buy
FS - For Sale
LFS - Local Fish Store
HOB - Hang On Back (usually referring to Skimmers/Refugiums)
FW/SW - FreshWater/Saltwater

Coral
SPS - Small Polyp Stoney
LPS - Large Polyp Stoney

Lighting
NO - Normal Output
VHO - Very High Output
MH - Metal Halide

There are tons more, spit em out everyone.

LR - Live Rock

LS - Live Sand

LW - Live Water

FOWLR - Fish Only With Live Rock tank

LMB - Lawn Mower Blenny (an adorable fish that eats algae)

BTA - Bubble Tip Anemone

RBTA - Rose Bubble Tip Anemone

LTA - Long Tentacled Anemone

CB - Captive Bred

WC - Wild Caught

CO2 - Carbon Dioxide (used in Calcium Reactors)

H20 - Hmm?  Can't remember...

pH - Potential of Hydgrogen

Ca - Calcium

Alk - Alkalinity

CaCO2 and CaCO3 - Jon knows these (Calcium Carbonate?)

just saw this

BSD:  Brine Shrimp Direct

http://reefcentral.com/modules.php?s=&name=Encyclopedia&op=terms&eid=2&ltr=all - http://reefcentral.com/modules.php?s=&name=Encyclopedia& amp;op=terms&eid=2&ltr=all

OH sure, kill the thread in one shot!

Thanks Corey

Weimers wrote: Co2 and Co3 - Jon knows these (Calcium Carbonate?)

I'm no Jon Finch, but I believ this one should be CaCO2 and CaCO3.  CO2 is listed above as Carbon Dioxide which is correct.  It can't be both. 

I never would have guessed that's what Ph meant.  I thought it just stood for Ph.

Suzy wrote: LBTR- Lake Bonneville Tufa Rock

HA!!!  You won't find that Acronym at Reef Central.

Ca++ = calcium
Alk = alkalinity
CO2 = carbon dioxide
CO3-- = carbonate (part of alkalinity)
HCO3- = bicarbonate (part of alkalinity)
CaCO3 = calcium carbonate sometimes called limestone, calcite or aragonite

H2O = water
H+ = hydrogen or more properly hydronium, H3O+
OH- = hydronium (part of alkalinity)
pH = (I hate "power of hydrogen") it's a measure of the H+ concentration.  The p should always be lower case and the H uppercase.

Na+ = sodium
Cl- = chloride
SO4-- = sulfate
Mg++ = magnesium
K+ = potassium
Sr++ = strontium
B(OH)4 = borate (part of alkalinity)

NH3 = ammonia
NH4- = ammonium
NO2- = nitrite
NO3- = nitrate
PO4-- = phosphate
I2 = iodine
I- = iodide
IO3- = iodate

I've probably forgot some too...

I think we should throw jfinch as an acronym on the list.

Renee- it's actually "power of the Hydrogen".

Adam

You know... I don't know which it is.  I'm pretty sure I was never told in college.  It wasn't until I was long gone from classwork that some old coot told me it was "power/potential of hydrogen" .  That is such an archaic term... Renee, you're not that old .

pH is -log[H+]  plain and simple

jfinch wrote: pH is -log[H+]  plain and simple

Really?  It could be
pH=pKa + log(salt/acid)
pH= -log10[H3O+]
pH= 14 - pOH (at 25C)

Adam
(and yes Jon I know this, but have no idea what my tank pH is)

Adam's making it harder then it really needs to be .  All those equations are mathematicaly the same.  What you really should have pointed out is that when dealing with seawater there are actually four pH scales!  pH(total), pH(seawater), pH(free) and pH(NBS).  We all use NBS calibration buffers so that scale is what we should be talking about, but if you read "real" seawater chemistry research it's almost always referenced to pH(total). 

And to be even more exact:
pH = alpha x log[H+]
Where alpha is the hydronium ion activity coefficient.  alpha is very close to 1 for freshwater, but is closer to 0.7 in seawater.

pH= 14 - pOH (at 25C)

A better expression is pH = pKw - pOH, because pKw isn't always 14 (even at 25C) because... pKw for seawater is about 13.4 so...
pH = 13.4 - pOH (at 25C in seawater)

pH=pKa + log(salt/acid)

That one is a very intersting method of approximating the pH of a buffered solution... I like that one.

hmmm... where to begin (or maybe not begin ).

1st:  none of this really matters to the average joe aquarist.  It's just the geek speak of chemists.

For Mark and anyone else with an inquisitive mind (a little more chemistry info):

all chemical equilibrium reactions can be described in this manner:

Given this chemical reaction  A + E = C + D

The amounts of each of those reactants and products can be described by this equation (the [x] brackets means concentration of x in molar units):

([C] x [D])/([A] x [E]) = K

K is a constant and can be found in chemistry textbooks for many reactions. 

If the reaction is between a stronger acid and weaker base then K is referred to as Ka. 
If the reaction is between a strong base and a weak acid then K is referred to as Kb. 
If the reaction is a salt that is dissolving (aragonite for example) then K is referred to as Ksp

So how does this apply to reefkeeping?

For water (hence pH):

H2O = H+ + OH- (water molecule dissolving into H+ (acid) and OH- (base) )

[H+] x [OH-] / [H2O] = Kw (could be refereed to as Ka or Kb, but water has it's own special disassociation constant, Kw)  since the solution is in water the concentration of water, [H2O], is equal to 1, And  [H+][OH-] = Kw.  Kw(seawater) = 4.0 X 10^-14.  Chemists don't like such small numbers and it takes too long in normal conversation so they talk about the pKw (BTW, this is the same reason that pH is used).  pK = -logK (looks just like the definition of pH doesn't it).  So the pKw of seawater is -log(4.0 X 10^-14) which is 13.4.  It's much easier to just say 13.4 then 4.0 x 10^-14 and they mean the exact same thing.

It's simple math to rearrange these equations to:
[H+][OH-] = Kw
p[H+] + p[OH-] = pKw    (I just took the log of both sides of the equation)
p[H+] = pKw - p[OH-]   (Just rearanged... and there's one of Adam's definitions)

This "principle" is applicable to the carbonate system (CO2 <--> HCO3 <--> CO3) which is what seawater alkalinity is really all about.  And it's applicable to the dissolving of aragonite or calcite:  Ksp(aragonite) = [Ca++][CO3--]

Chemistry's great!

Mark- none of it is important.  Your tank pH is a completely useless measurement.  Please forget everything you know about pH.

Jon- thanks for expanding even further.  I don't know why I just said that.  Anyway, I do like the additions and explanations you made in your last couple posts...... looks like pH isn't all that simple is it?

Adam

Adam's wrong.  pH is important.

looks like pH isn't all that simple is it?

Sure it is.  pH is simple in the same way that eating a donut is simple.  It just is and happens naturally.  But the little nuances of what makes each of those processes "work" are very complicated.

mmmm... donuts.

Mark- I'll say No.  The types of chemicals and ions in a tank don't affect pH.  And it has nothing to do with tank health. Aragonite doesn't have an impact.  CO2 doesnt' matter either.

A water change would fix any problem in this area.  But again, Jon is wrong, this stuff isn't important at all.

Adam

So for my simple mind could I say to a hobbyist that the ratio of the amount of and type of chemicals/ions in a tank, affects pH in a big way? And that this has everything to do with tank health?

For all intents and purposes, in seawater, pH is only effected by carbonate alkalinity (HCO3- and CO3--) and CO2.  None of the other major elements/chemicals/ions in the water have any effect.  pH is only one indicator of tank health.

could I say that pH is affected in a big way by the amount of Aragonite in the tank Versus the amount of decaying organic matter and level of CO2 in the tank?

No aragonite only has an effect on pH if it dissolves.  When it dissolves it releases CO3-- (see above) and causes the pH to increase.  But in seawater aragonite will not dissolve until the pH is in the mid 7s.

Is this why Aragonite is so important or is there something else like aragonite that also balances opposite decay and CO2 in the aquarium?

CO2 is a naturally occuring gas in our atmosphere and is constantly trying to reach equalibrium with the CO2 dissolved in water.  It will freely go in and out of solution.  I'm not sure I understand your question regarding balancing decay?

Adam said:
The types of chemicals and ions in a tank don't affect pH.
and
A water change would fix any problem in this area.

Riddle me this... You say the types of chemicals in your tank don't effect pH but a water change (which makes a change to those chemicals and ions) will fix a pH problem???

Riddle me this... You say the types of chemicals in your tank don't effect pH but a water change (which makes a change to those chemicals and ions) will fix a pH problem???

Jon- correct you caught me contradicting myself.  But I stand by that.  Here is why.  pH is a bunch of garbage if you ask me.  I say don't worry about.  None of those things are going to cause problems.  Like you said the only thing that could is CO2 or carbonates.  But it isn't like adding lugols solution is going to mess up your pH.
And if you do think you have a water quality problem, or if you do accidently dump in a bunch of kalkwasser or something like that.... well a water change is always a good idea.  It can't hurt, and it only helps.  So rather than explain to new hobbyists how pH works and the relationship of carbonates, I would rather just get people thinking "when in doubt to a water change".  I think that will serve them better.

Adam

jfinch wrote: But I personally hate it when someone "dumbs down" an explanation or answer to a question.

Really?  Even people who are considered to be even a little bit on the nerdy side (you know, people like me) don't like big answers.  Like I recently asked Dana Riddle (or should I say had him prove to me) what happens with food and photosynthesis.  Basically I didn't/don't care how it makes changes I just want the straight up answer "does food help my corals grow?". 
Or when I buy light bulbs I ask people "okay I'm going to buy new halide bulbs, what do you guys think I should buy".  I don't really care about PAR ratings, I just want someone to point to a bulb and say "that is the best". 

Now I do understand your point, and do agree with it in some regards.  I'm that way with fish food, and with fish compatability.  Every time someone makes a statement I want to know everything about why they said that. 

I guess it just depends on my interest in the subject.

Adam

jfinch wrote:  pH is simple in the same way that eating a donut is simple.

Sorry Adam, but I agree with Jon. So do I eat my donut with a fork or with my hands? What's the difference in pH between powdered, glazed and jelly-filled? Should I dip it in coffee or chase it with milk? Hostess or Krispy Kreme?

Not to make light of either of your convictions. I'm sure you both make great points, but I don't feel like going to another four years of school to find out. I wonder if a Chemistry 101 class at an upcoming meeting might make some of us on the message board feel less like we're watching an episode of Mensa Jeopardy.

I like Jamison's idea.  I would need extra caffeine beforehand, but a Chemistry 101 is a good idea.  We have had sort of a Lighting 101, and a few DIY 101 ideas. 

If we wanted, it could be a combo with a newbie lesson.  So it could be "common problems in a new tank" and "here's the chemical reason why you're having that problem." 

Or it could be: 

Here's what a calcium reactor can do for you.

Here's why Alkalinity is important.

Or it could be a straight-up, (tank up on Espresso everyone!) - lecture.

Jamison wrote: I wonder if a Chemistry 101 class at an upcoming meeting might make some of us on the message board feel less like we're watching an episode of Mensa Jeopardy.

I thought we already did that.  Last fall right?  Jon Finch led the meeting.
Check out the presentation over there <-------------

Adam