Bi-Weekly Discussion--- water balance

[tims]

Well gang we have started the year off pretty well so far ( i think we did anyway) with some nice topics with many asking ans answering.

FYI. the bi-weekly ( or longer) is for everyone. please if you have a question about the topic just jump in!

Water balance.....
Function: noun
: the ratio between the water assimilated into the body and that lost from the body; also : the condition of the body when this ratio approximates unity

this definition came from a medical dictionary.
but instead of looking at it as a human body, think of your tank as living body.




the second part of the definition is what i would like to look at and discuss.

the condition of the body (tank) when this ratio approximates unity.
think..Ph, Alk, Ca, P, N's etc..
what are ways we can keep this balance in line?

[leveldrummer]

test for these things, and learn how they all interact with each other would be the best bet right? i for one am having a tough time getting my calcium and alk up, they are at acceptable range right now, just not on the high side that i see alot of people keep, cal is at 380, alk is around 2.9 meq/l, and i cant do much else because i dont have a mag test, but i would like to know just how mag affects these other two.

[fyrfytr1717]

I'm afraid I'm not going to be able to contribute much to this one but I am looking forward to learning about this! Ammonia and nitrite are normal parts of a cycling tank after initial set-up but should not be found in measurable quantities after a tank has achieved "water balance". Nitrate will continue to build in a tank over time, is not toxic to fish in small quantities, and is removed through regular water changes. As for the other parameters, I'll hang out and learn. Out of curiosity, when discussing alkalinity, which units are the preferred ones for comparison? dKH, meq/l, or ppm CaCO3?

[tims]

Tony your doing great so far!

[leveldrummer]

Originally Posted by fyrfytr1717

I'm afraid I'm not going to be able to contribute much to this one but I am looking forward to learning about this! Ammonia and nitrite are normal parts of a cycling tank after initial set-up but should not be found in measurable quantities after a tank has achieved "water balance". Nitrate will continue to build in a tank over time, is not toxic to fish in small quantities, and is removed through regular water changes. As for the other parameters, I'll hang out and learn. Out of curiosity, when discussing alkalinity, which units are the preferred ones for comparison? dKH, meq/l, or ppm CaCO3?

i thought that in marine tanks, the nitrogen cycle is actually finished with our live rock and sand and you dont have nitrates, or at least a low consitent level, it should be turned into nitrogen gas and released or used by bacteria and other such cool stuff.

[tdwyatt]

Originally Posted by leveldrummer

i thought that in marine tanks, the nitrogen cycle is actually finished with our live rock and sand and you dont have nitrates, or at least a low consitent level, it should be turned into nitrogen gas and released or used by bacteria and other such cool stuff.

The only way there would not be some sort of nitrogen cycle would be if there wasn't any coming into o leaving the tank.

Sources coming in: feeding, top off water, salt mixes, filtration media, nitrogen gas via nitrogen fixing bacteria and cyanobacteria, importing creatures (fish, coral soft tissue, mucus, cleanup crew, sand bed creatures, etc), others I am sure that I am overlooking.


Export: specimen growth (astually, a biological sequestering into a closed compartment), denitrification in rock and saned beds, water changes, algal export via biomass removal.

Most of us think of the nitrogen cycle as just getting to a balance of the processing of ammonia to rapidly form nitrates, possibly the denitrification as well associated with low O2 environments, but the nitrogen cycle keeps turning in terms of the path if follows through the biological systems of our tanks.

It doesn't stop with deammonification and denitrification.

[Orient Master]

to new to the reefing to know anything but just test a lot a whole lot. So i guess my question is which test kit? I can't start to ballance what i don't know is high or low. I know some test kit's aren't really up to par. And some test kits are to be avoided at all costs.

[fyrfytr1717]

Originally Posted by tims

Tony your doing great so far!

All right! I'll take another stab at it. On a very basic level, pH never quite reaches "water balance" or "unity" as your definition refers to. It is constantly changing throughout the day. In a tank that has no external means of altering the pH, the sand (and rock?) provide a buffer to help keep it elevated in the neighborhood of ~8.2 like you would find in natural seawater.

In a small closed environment like a tank, pH will drop throughout the day due to algae and other CO2 consuming organisms removing CO2 from the water. It will also be raised throughout the day due to the production of CO2 by fish and other organisms that consume O2 and excrete CO2 as a byproduct. So far as I've been able to tell thus far (maybe because I only have two small fish in a large tank) the pH tends to drop during the part of the day when your lights are on as this is when algae is photosynthesizing and using up a significant amount of CO2. During the night, the algae slows down and the pH slowly returns to normal.

Again, this is just my very simplistic understanding of pH balance. Hopefully I'm on the right track...

[tims]

Tony, not bad at all!
Chris,
there are various test kits for everything out there now. the "master "kits will have most is not all for Ph, Ca, Alk, Nitrate,Nitrite , Amm. if you are adding anything else to the tank you need a kit for that( like Iodine)
there are a few digital meters out there too. i use a hand held meter to monitor my Ph.

Parameter:	Reef Aquaria Recommendation:	Typical Surface Ocean Value:1
Calcium	380-450 ppm	420 ppm
Alkalinity	2.5-4 meq/L 7-11 dKH 125-200 ppm CaCO3 equivalents	2.5 meq/L 7 dKH 125 ppm CaCO3 equivalents
Salinity	35 ppt sg = 1.026	34-36 ppt sg = 1.025-1.027
Temperature	76-83° F	Variable2
pH	7.8-8.5 OK 8.1-8.3 is better	8.0-8.3 (can be lower or higher in lagoons)
Magnesium	1250-1350 ppm	1280 ppm
Phosphate	< 0.03 ppm	0.005 ppm
Ammonia	<0.1 ppm	Variable (typically <0.1 ppm)

this is from a reef chem. artcile written by randy Homles -farley.

as you can see some of the numbers that tanks need to be are rather ...... varitable..

[tdwyatt]

Originally Posted by fyrfytr1717

...On a very basic level, pH never quite reaches "water balance" or "unity" as your definition refers to. It is constantly changing throughout the day. In a tank that has no external means of altering the pH, the sand (and rock?) provide a buffer to help keep it elevated in the neighborhood of ~8.2 like you would find in natural seawater...

Unfortunately, it is much more complex in seawater than that. Millero allocates an entire chapter (Chapter 6-"The Carbonate System," pp-267-322) to the balance attributed to pH from CO2 diffusion into seawater at the air/water interface and how it strongly affects the pH in seawater¹, as well as the interrelationships between pH and alkalinity (A_T), total CO2 (SCO2), and the partial pressure of CO2 in seawater (pCO2seawater). The interreltionship between these variables of seawater and the carbonate system is so strong that knowing any two of these four values allows us to calculate the other two values for a given set of circumstances. Any consideration of inorganic carbon levels in seawater MUST consider the rate of absorption of CO2 from the atmospohere (where currently the value is ~380PPM CO2 circa 2007 and rising as a consequence of fossil fuel burning and the production of cement).

(1) CO2 (gas-atmospheric) <---> CO2(aq-dissolved)

(2) CO2(aq) + H2O <---> H+ + HCO3-

(3) HCO3- <---> H+ + CO3--

(4) Ca++ + CO3-- <---> CaCO3(solid)

If any of you are interested, I'll show the kinetics of this system, but I'll warn you, it is not for the faint of heart...



Most of the inorganic carbon in the ocean is found below the thermocline in deep oceanic waters, and an even larger portion is sunk as inorganic carbonate solids as either reef geostructure or precipitated deep water solids, much to consider in terms of the big picture, much less to consider in our tanks that are less than a meter deep.


Also keep in ming that the inorganic carbnate species are not the only contributors to alkalinity in seawater: boron, silicon, magnesium hydroxides and free hydroxyl radical along with phospohate contribute each to some degree to total alkalinity:

Originally Posted by Millero

• Ionic specie . . . . . . %AT
• HCO3- . . . . . . . . . . 89.8
• CO3-- . . . . . . . . . . 6.7
• B(OH)4 . . . . . . . . . . 2.9
• SiO(OH)3- . . . . . . . . 0.2
• MgOH+ . . . . . . . . . . 0.1
• OH- . . . . . . . . . . . . 0.1
• HPO4- . . . . . . . . . . 0.1

[salt-rookie]

To me, good consistant husbandry practices are the key to keeping the water params in balance! Doing a 10-15% water change EACH AND EVERY week, allows the salt mix to replentish all trace and major elements. I have a large draw on calcium, alkalinity and magnesium. I boost these with a quality reactor, I drip kalk and I add epsom salts in my weekly water change. My params are as follows:

pH: 8.2 on reverse photoperiod
Calcium: 400-405 ppm
Alk: 8.2 dKH
Magnesium 1220
Specific Gravity: 1.026
Salinity 35 ppt
Temp 79-80 degrees F.

GOTTA use quality RODI water to mix your salt mix.

[fyrfytr1717]

Originally Posted by tdwyatt

Unfortunately, it is much more complex in seawater than that. Millero allocates an entire chapter (Chapter 6-"The Carbonate System," pp-267-322) to the balance attributed to pH from CO2 diffusion into seawater at the air/water interface and how it strongly affects the pH in seawater¹, as well as the interrelationships between pH and alkalinity (A_T), total CO2 (SCO2), and the partial pressure of CO2 in seawater (pCO2seawater). The interreltionship between these variables of seawater and the carbonate system is so strong that knowing any two of these four values allows us to calculate the other two values for a given set of circumstances. Any consideration of inorganic carbon levels in seawater MUST consider the rate of absorption of CO2 from the atmospohere (where currently the value is ~380PPM CO2 circa 2007 and rising as a consequence of fossil fuel burning and the production of cement).

(1) CO2 (gas-atmospheric) <---> CO2(aq-dissolved)

(2) CO2(aq) + H2O <---> H+ + HCO3-

(3) HCO3- <---> H+ + CO3--

(4) Ca++ + CO3-- <---> CaCO3(solid)

If any of you are interested, I'll show the kinetics of this system, but I'll warn you, it is not for the faint of heart...



Most of the inorganic carbon in the ocean is found below the thermocline in deep oceanic waters, and an even larger portion is sunk as inorganic carbonate solids as either reef geostructure or precipitated deep water solids, much to consider in terms of the big picture, much less to consider in our tanks that are less than a meter deep.


Also keep in ming that the inorganic carbnate species are not the only contributors to alkalinity in seawater: boron, silicon, magnesium hydroxides and free hydroxyl radical along with phospohate contribute each to some degree to total alkalinity:

Does this relate in any significant manner to the water in our tanks, or is it just an explanation of the balance of the ocean's water? I'm interested in the chemistry of it all, but I think the intricacies of the ocean are a little over my head at this point... (I do always find it interesting though to see the steps involved in chemical changes such as the one you demonstrated above.) Maybe a layman's translation of what you just posted or an idea of how it relates to tank water would be helpful. Just trying to grasp the basics at this point. Thanks!

[tims]

Kalk.
what is it used for? how do you use it?
can you make it? or just buy it?
How does this add or remove water balance in our tanks?

[tdwyatt]

Originally Posted by fyrfytr1717

Does this relate in any significant manner to the water in our tanks, or is it just an explanation of the balance of the ocean's water?

This is specifically explaining the oceanic balance, but at the surface, the ocean behaves pretty much the same way our tanks do. We don't get the benefit of the deep water revervoirs and sinks though, nor the effect of pressure on some of the chemical oceanography associated with large bodies of water. These equilibria DO help explain one of the issues we often see with hobbyists: chronically low pH in a system, and it is directly linked with the infusion of CO2 from the atmosphere. Most homes are fairly "tight," that is, they do not leak air either from the outside into nor the inside out of the house, and because of this, do not waste much energy heating or cooling air outside the home. This is good in that it saves us money and energy for HVAC expenses, however, for the marine aquaria we keep in our homes, this means that the indoor air will accumulate higher percentages of CO2 than the open atmosphere would normally present. Circa 2007, the pCO2atmosphere (reads as "the partial pressure of carbon dioxide in the atmosphere") is about 370 PPM or so, and accounts for some of the chronic acidification of the ocean we see in the reef waters around many coral biotopes of the world (the effect of which is another total discussion for some future biweekly discussion... ). Unfortunately, many homes have pCO2's INSIDE of 400 to 500 PPM, occasionally even higher...
... the effect of which is to drive the pH of the system down as CO2 passes through the air to water interface to form carbonic acid. Unfortunately, this reaction is very fast, and the kinetics are such that the forward reaction (forming carbonic acid from atomspheric CO2 as it dissolves in the water column) is about 670 times as fast as the reverse reaction (the reverse reaction is the dissociation of carbonic acid to form CO2 which can be gassed off from the surface if the concentration in the water column is higher than the atmospheric equilibrium would otherwise allow). It is this accumulation of CO2 in the home that is most often an issue in home aquaria with chronic low pH problems, especially in systems with CO2-driven calcium reactors where careful adjustment to optimum settings has not been undertaken.

The other reactions occur pretty much the same way they happen in the ocean, but the issue with the surface into water diffusion and disesolution of CO2 gas can be a real problem for home closed marine systems.

Interestingly enough, Tim has brought up a discussion topic that relies on the presence of CO2 inu tank water to perform as a balanced hermatypic supplement. Without CO2 in the water column, kalkwasser cannot manufacture the inorganic carbon alkalinity necessary to provide a balanced supplement for corals of both equimolar amounts of calcium and bicarbonate...

...Maybe a layman's translation of what you just posted or an idea of how it relates to tank water would be helpful. Just trying to grasp the basics at this point. Thanks!

If you need more, post a few specific questions. I'll post something on some of the chemistry of kalkwasser once I get home tonight or tomorrow.

HTH

[bubblybabs]

I did not see this thread when I asked about how often people put additives into their tank in the "regular" discussion group...

A few questions...

When I bought some frags the description of some of the corals said the frags would benefit from "the addition of strontium and other trace elements" so I bought a bottle of that stuff for the tank...

Now, one person says they don't add anything to the tank other than calcium... No-one said they added this other stuff...

So, I'm confused as to what to do... Should I add this stuff? Was it a waste of my money to buy the stuff? My fish store highly recommends Purple-Up so i've been adding that daily... But I also got bottles of Iodide, Essential Elements, and Strontium & Molybdenum...

I see there are tests out there for iodine and strontium, etc... Should I buy them?

Next question... I see reference to epsom salt additions to the tank for magnesium... How often do you check for your mag? Weekly? Or after a water change? As a matter of fact, do you always check your water perameters after a water change?

I understand time of day influences the pH... Do you make sure you test at the same time? If so, when? Should it be a few hours after the lights have been on?

Thanks,
Babs