are calcium reactors outdated now?

[jda]

I consider a CaRx more safe since I have never really seen them crash a tank without days or even weeks of neglect. Dosing pumps have gotten better and the instances of massive amounts of calcium or carbonate being dumped in are down, but it still happens.

With a CaRx, if things are going to drift, it happens slowly outside of some extreme edge case.

A well tuned reactor will barley move your tank pH at all. I know that co2 is part of the equation, but it is not significant in practice, IME. Letting a lot of raw co2 pass through your reactor into the tank that is not dissolved can lower the pH, but that is not a CaRx thing, that is a hobbyist thing. You can tune them to where this does not happen. The excess co2 thing is usually a byproduct of solenoids opening and dumping - bad approach, IMO.

Although minor and can happen in other ways, but I also like the traces that I get from melting natural media. This allows me to just change water and have what appears to be a complete solution.

Personally, I would not run a tank without a CaRx and I know and understand the alternatives from 2/3 part and kalkwasser. It just works for my personality and needs.

 

[HuduVudu]

If you just mean removing all of the extra CO2 you added, the pH comes right back to where it started before adding CO2.

With the pH dropping below 7?

EDIT: Please note I am talking about salt water not RO water.

 

[HuduVudu]

I agree that dosing pumps can vary and that can lead to drift in values, but the same would be said about flow through a CaCO3/CO2 reactor being variable with variable delivery of alk and calcium at a fixed pH (if it is pH controlled).

Reactors are providing both pieces of the equation at once. Drifting has little effect because of that.

Remember my question about how much I could put of 2 part in a bucket. If I could put a decent amount of two part in a bucket with tank water then the dosing pump would be removed from the equation, as though it where dosing from a reactor.

 

[jda]

Also, if you do have low pH and even have a poorly tuned reactor, the air in your home/office is the issue, not even a poorly tuned reactor. Sure, tuning the reactor properly certainly can help, but not nearly as much as airing out your house.

 

[HuduVudu]

Personally, I would not run a tank without a CaRx and I know and understand the alternatives from 2/3 part and kalkwasser. It just works for my personality and needs.

I think that this is what is being lost here. There are pros and cons to every system. Each person has to decide what works best for them.

One of the cons of CaRxs is that they are designed for larger systems. With a little engeniuty they can be adapted. As can every system. If I were to dose 2 part I would test to see how much 2 part I could put in a bucket of salt water and then single dose from there.

 

[HuduVudu]

Also, if you do have low pH and even have a poorly tuned reactor, the air in your home/office is the issue, not even a poorly tuned reactor. Sure, tuning the reactor properly certainly can help, but not nearly as much as airing out your house.

Seriously this is a much more common issue than the reactors.

And because people are not aware of this effect they just throw Kalk at the problem.

I stated before and I will state again ... I think that a CO2 monitor is as important if not more important than alk or calcium tests.

 

[Randy Holmes-Farley]

With the pH dropping below 7?

EDIT: Please note I am talking about salt water not RO water.

You can take it all the way until it is bubbling with excess CO2, then bring it back, and the pH is unchanged unless you dissolved something that was a solid material before adding the CO2.

 

[HuduVudu]

You can take it all the way until it is bubbling with excess CO2, then bring it back, and the pH is unchanged unless you dissolved something that was a solid material before adding the CO2.

How do you get the OH- back?

 

[Randy Holmes-Farley]

Reactors are providing both pieces of the equation at once. Drifting has little effect because of that.

Remember my question about how much I could put of 2 part in a bucket. If I could put a decent amount of two part in a bucket with tank water then the dosing pump would be removed from the equation, as though it where dosing from a reactor.

I agree they would drift together, but calcium drift is pretty unimportant while many folks care a lot about alk drift, whether or not calcium moves too.

 

[HuduVudu]

calcium drift is pretty unimportant while many folks care a lot about alk drift, whether or not calcium moves too.

To a point. I am currently dealing with excess alk and it is nothing to do with the reactor.

From my experience and what I see on the boards alk is too abundant.

As to the drift my point is centered around the sodium chloride balance. The problem is that day in and day out for 8 years I have had to deal with alk calcium. I need something reliable. Dosers that can't keep the balance aren't it.

Yes, I am aware that you can calibrate them. Trust me I use them even now. Only the difference now is that I use them in ways that I am not as concerned about their drifting because I know that they do.

Sooooooo you work in a fancy lab ... do the really high end dosers drift or is just the nature of the beast?

 

[Randy Holmes-Farley]

How do you get the OH- back?

OH- always present in rapid equilibrium with H+. If you know the H+ you know the OH-. If what you do impacts H+ up or down, it impacts OH- down or up exactly conversely.

H2O <--> H+ + OH-

In this question, remioving CO2 removes H+ and removing H+ adds back OH- instantly.
Let's suppose you add a lot of CO2 so all of the alkalinity is present as bicarbonate.

HCO3-

and then you remove CO2

2HCO3- --> CO3-- + H2CO3 --> CO3-- + CO2 + H2O

Essentially you convert two bicarbonate into one carbonate

That raises pH because the ratio of carbonate to bicarbonate fixes the pH. For any given ratio of bicarbonate to carbonate, there is only one pH (at a given alkalinity). The determining equation for that relationship is:

2. Ac = (K1KHPCO2 / [H+]) + 2(K1K2KHPCO2 / [H+]2)

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

reefs.com

 

[Randy Holmes-Farley]

Sooooooo you work in a fancy lab ... do the really high end dosers drift or is just the nature of the beast?

I don't use dosing pumps for anything in the lab.

 

[SamsReef]

i will most likely restart the CR as my acros are growing nicely these past months... i will add sand to the second chamber instead of reactor media to try and absorb some of that Co2 so it does not lower tank PH

I have tried that with high quality Tropic eden reef flakes and crappy caribsea sand and both had super high phosphates in the effluent. Small improvement in ph but huge phosphate factory

Sam

 

[jda]

You want sand/substrate that was in the water and not on the beach. Most sand is relatively phosphate free, but some can be bound with terrestrial phosphate. Sand in the water should be mostly free of bound phosphate since the ocean is so low to begin with. While I do believe that bagged live sand is a joke for all of the "live" stuff, it is usually collected from the water and is better in this regard.

You also do not need a second chamber if your reactor has a good tune. A second chamber can be good to take care of some of the extra raw co2, but it still does not appear to ever get it all and you don't need extra co2 leaving the reactor in the first place.

 

[HuduVudu]

OH- always present in rapid equilibrium with H+. If you know the H+ you know the OH-. If what you do impacts H+ up or down, it impacts OH- down or up exactly conversely.

H2O <--> H+ + OH-

In this question, remioving CO2 removes H+ and removing H+ adds back OH- instantly.
Let's suppose you add a lot of CO2 so all of the alkalinity is present as bicarbonate.

HCO3-

and then you remove CO2

2HCO3- --> CO3-- + H2CO3 --> CO3-- + CO2 + H2O

Essentially you convert two bicarbonate into one carbonate

That raises pH because the ratio of carbonate to bicarbonate fixes the pH. For any given ratio of bicarbonate to carbonate, there is only one pH (at a given alkalinity). The determining equation for that relationship is:

2. Ac = (K1KHPCO2 / [H+]) + 2(K1K2KHPCO2 / [H+]2)

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

reefs.com

I am not seeing this empiricly.

Water taken from tank and carbonated. Then protien skimmer put in bucket to provide gas exchange. After one day pH just slightly above 7 (7.2 if memory serves). No change (other than a lot of evap) after several days.

I am reading the article.

But it seems to me that the the H+ will bind the OH- and leave the CO3- from 8pH to 7pH but then behave "normally" form 7pH to <7pH, so after allowing outgas will only rise to 7 leaving CO3- bound. Thus exchanging OH- for CO3- on the difference between 8pH and 7pH

Not sure where the OH- comes from after 7pH. Was working on understanding why salt water is basic.

 

[Randy Holmes-Farley]

Not sure where the OH- comes from after 7pH. Was working on understanding why salt water is basic.

It comes from the autoionization reaction of water. It is very fast and is always at equilibrium.

H2O --> OH- + H+

If you take water (any water) and remove H+ in any fashion, OH- instantly increases.

Le Chatliers principle details why. Remove either component on the right (or both) and more autoionization of water takes place, establishing a new equilibrium at the new pH.

H+ and HO- always fit the equation:

[OH-] x [H+] = kw = 1 x 10-14

(kw varies a bit by solution, but it is always fairly close to 10-14).

Self-ionization of water - Wikipedia

en.wikipedia.org

 

[Macdaddynick1]

Thought experiment for you. What happens if you carbonate just salt water and then let said water outgas. This is just a glass of salt water that you pulled from your tank.

What will be the pH of the water after ALL of the CO2 is outgassed?

 

[HuduVudu]

It comes from the autoionization reaction of water. It is very fast and is always at equilibrium.

H2O --> OH- + H+

If you take water (any water) and remove H+ in any fashion, OH- instantly increases.

Le Chatliers principle details why. Remove either component on the right (or both) and more autoionization of water takes place, establishing a new equilibrium at the new pH.

H+ and HO- always fit the equation:

[OH-} x [H+] = kw = 1 x 10-14

(kw varies a bit by solution, but it is always fairly close to 10-14).

Self-ionization of water - Wikipedia

en.wikipedia.org

Add H+ in and the equilibrium will adjust down near instantly. Removing the same amount of OH- as is added with the H+. Remove H+ (or add OH-) and equilibrium will adjust up with the same effect. Is this how autoionization works?

What happens to a solution of sodium hydroxide in pure water if we add pure carbonated water? Assuming the gas constiuents over the water maintain the same parameters before and after the addition of carbonated water?

 

[Randy Holmes-Farley]

Add H+ in and the equilibrium will adjust down near instantly. Removing the same amount of OH- as is added with the H+. Remove H+ (or add OH-) and equilibrium will adjust up with the same effect. Is this how autoionization works?

Yes. it's not quite as much as OH- removed as the H+ is added, because some remains (which is why pH changes as new amounts of OH-a nd H+ stabilize with each other).

What happens to a solution of sodium hydroxide in pure water if we add pure carbonated water? Assuming the gas constiuents over the water maintain the same parameters before and after the addition of carbonated water?

Start with OH- and add CO2. All of these happen:

OH- + CO2 + H2O --> HCO3- + H2O
OH- + HCO3- --> CO3-- + H2O
OH- + H+ --> H2O

Bicarbonate and carbonate rise, OH- falls, H+ rises, and hence, pH falls. Alkalinity is unchanged.

 

[HuduVudu]

OH- + CO2 + H2O --> HCO3- + H2O

Did you mean?
CO2 + H2O --> HCO3- + H2O

Carbonate buffers are consumed before the OH- ... correct?

Maybe this is what I am missing?