Why use both

[reef]

Here is a article i found about the pros v cons of using a calcium reactor and kaltwasser at the same time.

K A l k w A s s e r - K A l k r e A k t o r - pros and cons

on www.Lars Sebralla.de

Dipl. Ing. (FH) Lars Sebralla

The general function mechanisms and impacts of the lime water method and the lime reactor are explained, confronted and regarded from a chemical side, which is easily understandably stated.

K A l k w A s s e r

Kalkwasser sounds itself for the Meerwasseraquarianer very promisingly and should be to use so simple and economical. If one analyzes however the term "kalkwasser" more near, some surprising result.

Of what does kalkwasser actually consist? One takes calcium hydroxide, gives it in osmose water, agitates several times and leaves the mixture untouched. After some time one gives the clear liquid to the sea water aquarium. Was that everything? Is it so simple? What actually happens and which is calcium hydroxide for a nonchemist? Questions over questions, which must be answered.

Calcium hydroxide

Calcium hydroxide is simplifies a substance made of calcium (approx.), oxygen (O) and hydrogen (H). The oxygen and the hydrogen are firmly connected and result in a hydroxide (OH). This OH is strongly basic (alkalinely) and has a pH value of 14. Two this OH are firmly connected with a calcium (approx.). The two as index one writes (2). Calcium hydroxide is thus:

Ca(OH)2

If calcium hydroxide in water is given, a part of the connection goes "apart", it is solved. Made of calcium hydroxide then one calcium ion (approx. 2+)and two hydroxyl ions (2 OH become-). This looks as follows:

Ca(OH)2 ® approx.2+ + 2 OH-

What means this for the Aquarianer?

"kalkwasser"

Calcium hydroxide separates only badly in water. For this reason calcium hydroxide in the container always stays as white solid. In the clear solution over it are calcium ions, hydroxyl ions and naturally water. The pH value is with approx.. 12,45. This clear solution is now the "kalkwasser" thus:

Approx.2+ + OH- in water

Lime

Where now is the lime in the kalkwasser? Lime is a connection of calcium (approx.), carbon © and oxygen (O). A carbon © is firmly connected with three oxygen (3 O) and results in thus CO3 , a carbonate. This carbonate increases the carbonate portion e.g. in the aquarium. A calcium (approx.) is now connected with a carbonate (CO3) and results in calcium carbonate or, like the vernacular says, lime. Thus is lime:

CaCO3

Lime and "kalkwasser"

Now is the question: "where is the lime in" the kalkwasser "?" yet doesn't answer, or nevertheless? The answer is not obvious, it is a lime in the kalkwasser.

Lime develops after some time in the "kalkwasser". Only if carbon dioxide (CO2) from the air, at which surface of the "kalkwassers" arrives, this formally aspirated and forms then lime. This is not soluble in the "kalkwasser" and gives likewise a white sediment. For this reason "kalkwasser" should be located not openly, but keep in a lockable container, e.g. to a can. If the "kalkwasser" (the clear solution) is used up, new osmose water is given on the arrears. After a certain time the sediment in the container is exchanged and fresh calcium hydroxide is used, because ever more insoluble lime is present and ever fewer calcium hydroxides.

Calcium hydroxide solution in the aquarium

If the clear calcium hydroxide solution, i.e. calcium ions (approx.2+) and hydroxyl ions (OH-) to the sea water aquarium is given, a reaction takes place, it develops simplified representedfor calcium hydrogencarbonate(CaHCO 3), thus with the carbon dioxide loosened in the water(CO 2):

Approx.2+ + 2 OH- + 2 CO2

¯

Ca(HCO3)2

The calcium hydrogencarbonate is not stable and disintegrates into an calcium ion (approx.2+) and an hydrogencarbonate ion (HCO3-), thus:

Ca(HCO3)2® approx.2+ + 2 HCO3-

Since an alkaline pH value is present, reacts the hydrogencarbonate ion (HCO3-) with a hydroxyl ion (OH-). Now an carbonate ion (CO 32)and water develop, thus:

HCO3- + OH- ® CO32+ H2O

Now also the carbonate portion in the aquarium rises. The rise depends thus before all of the pH value and of the carbon dioxide portion in the aquarium water.

Result "kalkwasser"

The so-called "kalkwasser" does not consist only of calcium ions and hydroxyl ions and has with lime anything to do. Only if the clear calcium hydroxide solution is given to the aquarium develops at the end carbonate. An accurate controlling of the carbonate portion is hardly possible, since it depends before all of carbon dioxide content in the water.

--------------------------------------------------------------------------------

K A l k r e A k t o r

Here the Aquarianer thinks usually of very complex, complicated and above all very expensive devices. It is to take place here no comparison of products, but state only fundamental principles.

If one analyzes however the term "lime reactor" more near, one experiences some surprising likewise. All the same whether built or bought, often one hears problems such as karbonathaerte (today: Saeurekapazitaet to pH 4,3) does not rise, too little calcium, pH value falls u.s.w. But actually the lime reactor is to function nevertheless according to a so simple principle. One gives carbonic acid to a container (reactor), filled with a substrate, and at the end comes a solution out with...? This is so not only too simply represented, but also still wrongly. Therefore step for step.

Function mode

A goal of the lime reactor is it to divide the substrate in its inside into the individual components to thus solve. These arrive then into the sea water aquarium. The lime reactor is filled with a substrate, which lime (CaCO3) must contain. Lime dissolves in sour solutions easily, while in alkaline solutions the lime is present as white solid. Since a sea water aquarium has mostly an easily alkaline pH value between 8,0 and 8,4, the substrate does not dissolve. For this reason the pH value must be brought in the reactor into a sour range (smaller 7). This can happen not in the aquarium but in the lime reactor is practiced. In order to lower the pH value in the reactor, carbon dioxide (CO 2)becomes as gas (and not carbonic acid!) admitted. The carbon dioxide (CO2) is loosened in the water (H2 O). Carbonic acid develops, thus:

CO2 + H2O ®H2CO3

This reaction does not change the pH value yet. Carbonic acid is however very unstable and disintegrates simplified into an acid (H+) and into a hydrogencarbonate (HCO3-), thus:

H2CO3® H+ + HCO3-

Now, if the acid (H+) is present, the pH value in the reactor is lowered. If the pH value is low enough, the substrate dissolves slowly. The insoluble lime (CaCO3) is converted now simplified by the "acid" (H+) into soluble calcium hydrogencarbonate (Ca(HCO3)2).

CaCO3 + H+ ® Ca(HCO3)2

The calcium hydrogencarbonate is not stable and disintegrates into an calcium ion (Ca2+) and an hydrogencarbonate ion (HCO3-), thus:

Ca(HCO3)2® approx.2+ + 2 HCO3-

Thus calcium ions (approx. 2+)and hydrogencarbonate ions (HCO 3-)arrive in the sea water aquarium.

Since an alkaline is present pH value in the sea water aquarium, reacts the hydrogencarbonate ion (HCO3-) with a hydroxyl ion (OH-), which is in great quantities in the aquarium present. Now an carbonate ion (CO 32)and water (H 2O) develop, thus:

HCO3- + OH- ® CO32+ H2O

Now also the carbonate portion in the aquarium rises.

Dissolution of the substrate

In order to accelerate a dissolving, a high flow rate must be present in the reactor. In to broad reactors (diameter more largely 12 cm) very strong pumps must be used (more than 2,500 litres per hour), in order to receive a high flow rate. Also the use of fine substrates leads to a strong reduction of the flow rate in the lime reactor. The substrate has a larger surface for the acid attack, is however too small the current, collects themselves the CO2vesicles in the substrate and results in large CO2blisters. In these places hardly substrate can be dissolved. In some reactors even the substrate and a large gas bubble lift themselves become visible.

Function & performance inspection of lime reactor

Each lime reactor can be completely simply tested. Vibrate your lime reactor easily. Now if gas bubbles from the substrate should ascend, the flow rate is too small and the lime reactor does not work to 100%. In such cases the substrate should be exchanged against a rougher material, since hardly carbon dioxide can collect itself there.

If no gas bubbles should ascend, you can determine the maximum achievement of the reactor as follows. Close the return of the lime reactor in the aquarium. That CO2entry is not changed. Now the pH value in the reactor always falls further and it dissolves ever more substrates. Thus the water with calcium ions (approx. 2+)and hydrogencarbonate ions (HCO 3-)enriches itself. The water in the reactor is clear. Suddenly this and the whole reactor change are white (looks like milk). If this should not happen, but gas bubbles in the substrate to settle, which become visible by easy vibrating, it must being proceeded like above described.

Max. achievement of a lime reactor

Why does the lime reactor color itself suddenly white? Because no fresh aquarium water can into the lime reactor influxes, return in the aquarium is closed, more lime in the water solved than possible is. This surplus falls suddenly in few seconds as white solid lime (CaCO3) out (supersaturation). Now the reactor is used to 100%. Now the return is opened in the aquarium and as soon as the reactor is again clear, can the calcium content, which is measured KH- and the pH value. Calcium values of over 1.500 mg/L and KH values over 60 are not rarity. By the variation of the return quantity into the aquarium and the carbon dioxide quantity (CO2) into the lime reactor now arbitrary KH is adjusted -, approx. and pH values.

Ex.: Little CO2 and high return in the aquarium results in a small dissolution of the substrate (a little approx.2+ and KH). Much CO2 and little return results in a high resolution of the substrate (much approx.2+ and KH).

Substrate for dissolution

If one uses now a substrate, which consists of pure lime, then only calcium ions (approx.2+) and Hydogencarbonat ions (HCO3-) are led in the aquarium. E.g. if Korallenbruch is used, then pollutants are set free such as phosphate, aluminum and Kieslesaeure additionally and enrich themselves in the water. Here it is pointed out that often many more phosphates by dissolving Korallenbruch into the aquarium comes when one thinks. Analyses showed up to approx.. 1600 mg phosphate per kg of Korallenbruch to be set free. Further there can be the problem with some pressed lime substrates that fine particles can arrive into the aquarium and lead to a turbidity.

Result lime reactor

The lime reactor enriches the aquarium water with calcium ions (approx.2+) and Hydogencarbonat ions (HCO3-). The pH value is raised and stabilized by the addition of hydrogencarbonate. When using shell greeting still further trace elements are brought in.

With a lime reactor arbitrary KH- and calcium values can be adjusted in the sea water aquarium without problems. In the natural sea water the KH lies with approx.. 8 and the calcium content with approx.. 400. KH values of 14-18 and calcium values of 500-800 mg/L, e.g. in a Steinkorallenaquarium can be realized and known also without problems large advantages to bring.

--------------------------------------------------------------------------------

Problems with the employment of kalkwasser and lime reactor

After the function and impacts are described, some general problems are addressed.

pH problems with the lime reactor

The output water of the lime reactor has a sour pH value (e.g. 6.2) and thus a surplus of acid (H+), otherwise would be the pH value not under 7. Now the conclusion lies close, if a water with e.g. pH 6.2 into the sea water aquarium, which has a pH of e.g. 8.1, drips, the pH value in the aquarium to sink can. Possible consequence: The water from the reactor must be raised in the pH, before it arrives in the aquarium. Possibilities are to be ventilated e.g. the water specially, before it arrives in the aquarium or the water by a protein skimer to send. In this way carbon dioxide is eliminated.

pH rise in the output water of the lime reactor?

What happens during a pH rise with the return water from the lime reactor? The water took up the maximum quantity of calcium ions (approx. 2+)andHydogencarbonat ions (HCO 3 -)atthe withdrawal pH value, if the reactor is optimally adjusted. Now the pH value is increased. As describes already further above, lime separates in the sour water on and in the alkaline lime precipitates as white solid. If the pH value of the return water of the lime reactor is increased, thus less lime can be loosened and thus the surplus precipitates as white solid. It can be determined e.g. at a white precipitation in the container, where the water is ventilated or in the foam pot of the protein skimer is snow-white arrears.

Which happens however, if the return water drips in the sea water aquarium (does not flow!), which a pH of e.g. 8.1 has? Here also does lime precipitate? The return should always take place into the current. By the immediate distribution drop in many litres aquarium water is prevented failing, there now the content of calcium ions (approx.2+) and Hydogencarbonat ions (HCO3-) in the whole aquarium distributed and no longer highly concentrated is as in the lime reactor exit.

Result

A pH increase of the output water of the lime reactor provides for a precipitation of the lime loosened before. The effect of the lime reactor is thus partly neutralized.

--------------------------------------------------------------------------------

Simultaneous enterprise of lime reactor and "kalkwasser"

Some sea water aquariums operated with a lime reactor and at the same time consists the refilling water of "kalkwasser". And sometimes the KH- and/or calcium values are nevertheless in the aquarium not sufficient. What can this lie? Are the devices laid out too small or do play nevertheless still different factors a role?

As model one can understand oneself a sea water aquarium (pH 8) as a container, in which a lime reactor an calcium ion (approx.2+) and an Hydogencarbonat ion (HCO3-) gave. The hydrogencarbonate ion is converted fast into an carbonate ion (CO32), sees above. The two ions are complete free and to them meet and again for lime (CaCO3) form, last it for a very long time. Now comes however from the "kalkwasser" e.g. 100 calcium ions (approx.2+). In the container are now 101 calcium ions (approx.2+) and an carbonate ion (CO32). Now is the probability that an calcium ion finds the carbonate ion much more largely and thus much fast lime precipitates. This effect is to be also observed, if "kalkwasser" is given by hand directly to the aquarium. Then the place of the a run colors itself for short time whitish to milk-colorends.

Result

By the simultaneous employment of lime reactor and "kalkwasser" the carbonate becomes from the aquarium as lime pleases and is not the korallen any longer at the disposal. "kalkwasser" works against the lime reactor. Thus should be used only one method, "kalkwasser" or lime reactor, whereby with a lime reactor the KH content and the calcium content let adjust accurately.

The increased CO2entry by the lime reactor can promote alga growth, be present before all if phosphate and nitrate to increased concentrations

[jetskisteve]

gibberish :-?

[Nicks]

'Gibberish and so what'!! is what this article got on Ultimate Reef.

I trust guys who use both and have great reef tanks which is most of us.

Nicks

[reef]

This should have been posted in the advanced section. Did not expect you to understand.