start using kalkwasser

[arman]

Hi my friends.Ive started to use kalk for maintaining my parameteres and have watched related videos related to.The first question is that when i put the kalk in the water in a bottle and shake it,after 6 hours the water wasnt clear.Is it normal or not?
The other question(not related to kalk)is that is supplementing iodine in a reef tank necessary or not?

 

[Oscar47f]

Was the water R/O water? and i don't think its necessary a good water change schedule with a good salt should have the necessary amounts of iodine in it... and there is such a thing as overdosing so if you do dose get a test kit for it...

 

[Elementalj]

Precipitation?

 

[Oscar47f]

Yeah once the water becomes saturated a precipitate forms because theres no more free h2o to bond with but it usually settles to the bottom

 

[Elementalj]

Yeah once the water becomes saturated a precipitate forms because theres no more free h2o to bond with but it usually settles to the bottom

That's what I thought. [emoji6]

 

[Randy Holmes-Farley]

I discuss precipitation with limewater in these two articles:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-07/rhf/index.htm

What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-01/rhf/index.htm

from the first one:

Precipitates Where Limewater is Added

When limewater is added to seawater, a cloudiness can form almost immediately (similar to that in Figure 3, although not usually that intense). This initial cloudiness is magnesium hydroxide, Mg(OH)2, and it forms when the water's pH rises into the low to middle 10's. Theoretical and experimental reasons for believing this material to be Mg(OH)2 (and not magnesium carbonate or calcium carbonate, for example) are given later in this article. As the limewater is mixed in, the local pH around the particulates drops, and as soon as it drops below pH 10, the magnesium hydroxide dissolves.


Precipitates on Top of Limewater
The precipitate that forms on the top of limewater is calcium carbonate (Figure 5). Limewater is high in calcium (about 800 ppm at saturation) and is very high in pH (pH 12.54 at saturation), meaning that it contains a lot of hydroxyl ions (OH-). When carbon dioxide from the air encounters the water, it hydrates to form carbonic acid:

(1) CO2 + H2O → H2CO3

Then, if the pH is above 11, as it is in limewater, the carbonic acid equilibrates to form mostly carbonate:

(2) H2CO3 + 2OH- → 2H2O + CO3--

It is the carbonate that we are concerned with in the formation of insoluble calcium carbonate, both on the surface of, and inside, the limewater:

(3) Ca++ + CO3-- → CaCO3 (solid)

The result of this reaction is visually obvious. The calcium carbonate can be seen as a solid crust on the limewater's surface that has been exposed to the air for a day or two (do not bother to remove this crust; it may actually be protecting the underlying limewater from further penetration by carbon dioxide). The formed solids also settle to the bottom of the container, and can, in fact, form down inside it. Since solid calcium carbonate is not an especially useful calcium or alkalinity supplement, this reaction has the effect of reducing the limewater's potency. With sufficient exposure to air, such as by aeration or vigorous agitation, this reaction can be driven to near completion, with little calcium or hydroxide remaining in solution.

This reaction is the basis of the claims by many aquarists that limewater must be protected from the air. It is also the basis of the claim that limewater reactors (Nilsen reactors) are to be preferred over delivery from still reservoirs of limewater. Neither of these claims, however, stands up to experimental scrutiny, as I showed in a previous article.

Precipitates on the Bottom of Limewater Reservoirs

The solids on the bottom of a limewater reservoir (Figures 5 and 7) contain everything that did not dissolve, or that dissolved and later precipitated from solution. Such solids could contain magnesium hydroxide and carbonate, calcium hydroxide and carbonate and a variety of other impurities such as copper salts, alumina, silica, etc.

In order to determine what is in these deposits, I tested a sample of the white solid material that had been collecting for months on the bottom of my limewater reservoir, and detailed the results in a previous article. I removed the white sludge along with some limewater. The mixture of solid and liquid was acidified to dissolve it, and it was tested for calcium, magnesium, and strontium. The results are shown in Table 1. Only relative concentrations are shown as no effort was made to dry the sample prior to analysis, making absolute concentrations meaningless.

As anticipated, based on the very low solubility of magnesium hydroxide and the high concentration of hydroxide ion in limewater, the solid material on the bottom of the limewater is enriched with magnesium. Relative to calcium, magnesium is enriched by a factor of 13 in the sludge compared to the solid starting quicklime. This magnesium may be present as both magnesium hydroxide and magnesium carbonate, but because magnesium carbonate is fairly soluble compared to calcium carbonate, it is most likely that the primary magnesium salt is magnesium hydroxide. It may also be mixed calcium and magnesium carbonates.

Interestingly, strontium is actually depleted by a factor of two relative to solid starting quicklime, indicating that it is less likely than calcium to end up on the bottom of the reservoir. While strontium carbonate is somewhat less soluble than calcium carbonate, the strontium concentration in the limewater is so low that SrCO3 may not actually be saturated, so it may not precipitate at all. The strontium that is there may simply be copreciptiated with calcium carbonate.

Phosphate, for example, would be insoluble in limewater, precipitating as calcium phosphate. Many toxic metals, such as copper, are also insoluble in the high pH of limewater, forming carbonates or oxides. These metals can also bind directly to undissolved lime or to calcium carbonate precipitates, as I showed in a previous article. In a sense, this precipitation can purify the limewater so that in some cases it may be even purer than the starting water or lime.

This purification is also seen in practice by many aquarists who have noticed the solids on the bottom of their limewater containers discolor, often to a bluish/green color suggesting copper. For these reasons, I recommend that lime solids not be dosed to aquaria when it is possible to avoid it. Letting the limewater settle for a few hours to overnight will permit most of the large particles to settle out, and whether it looks clear at that point or not, it is likely fine to use. In general, it is a good practice to leave residual solids on the bottom of limewater reservoirs rather than cleaning them out every time, as they may actually help purify the water by these precipitation mechanisms. Once the solids discolor, or have been collecting for 6-12 months, however, they should be discarded.

limewater to the aquarium (Figure 8). Some of this material will have been formed in the reservoir, and would therefore have been carried into the tubing in particulate form. These solids will be similar in composition to those found on the bottom of the limewater reservoir (described in the previous section). Some of this material, however, may form in situ as carbon dioxide enters the limewater through the walls of the tubing. Different materials have different permeability toward carbon dioxide, and different thicknesses will also alter its diffusion into the tubing. The diffusion can be sufficient, however, that over the course of a year significant amounts of calcium carbonate solids may accumulate in this way, and may eventually clog the tubing. For this reason, I flush acid through the system once a year or so to dissolve this calcium carbonate buildup.

Precipitates from Overdosing Limewater

When limewater is substantially overdosed, the transient precipitation of magnesium hydroxide from normal use may not be the only precipitate that forms. If the pH becomes elevated and stays that way long enough, calcium carbonate can precipitate throughout the water column. In such situations, the entire aquarium can become very cloudy, looking almost like skim milk (Figures 9 and 10). Such precipitation events have the beneficial effect of lowering the pH and alkalinity that were raised by the overdose, limiting the ongoing damage that takes place. In many cases, there is no apparent harm after a day or two, but in a few rare cases, when the overdose was especially extensive, a tank crash can occur, killing many organisms.

The following important points should help in dealing with a limewater overdose:

1. Don't panic! These overdoses do not usually cause a tank to crash.

2. The primary concern is pH. If the pH is 8.6 or lower, you need not do anything. If the pH is above 8.6, then reducing the pH is the priority. Direct addition of vinegar or soda water is a good way to accomplish this goal. Either one mL of distilled white vinegar, or six mL of soda water, per gallon of tank water will give an initial pH drop of about 0.3 pH units. Add either to a high flow area that is away from organisms (e.g., a sump).

3. Do not bother to measure calcium or alkalinity while the tank is cloudy. The solid calcium carbonate particles will dissolve in an alkalinity test, and all of the carbonate in them will be counted as if it were in solution and part of "alkalinity." The same may happen to some extent with calcium tests. Wait until the water clears, and at that point, alkalinity is more likely to be low than high. Calcium will likely be mostly unchanged.

4. The particles themselves will typically settle out and disappear from view over a period of 1-4 days. They do not appear to cause long term detrimental effects to tank organisms.

5. Water changes are not necessarily beneficial or needed in response to a limewater overdose.

 

[arman]

I use RO water for it.some of it just precipitated but its not clear yet.

 

[Randy Holmes-Farley]

I use RO water for it.some of it just precipitated but its not clear yet.

Let it settle 24 h, then use it even if a little cloudy.

 

[nvy]

I mix mine directly in my ATO container and leave it to settle. Sometime it pumps it up before settling down and the may DT get a little cloudy. no big deal. goes away after an hr.

 

[arman]

I made 1gallon of kalkwasser and as you know after a while some of it just precipitated at the bottom.My question is that can i make the other one gallon in that or i need to clean it and then make another one?

 

[httorihanzo]

I guess I would piggy back that last question by saying that I've mixed Kalk in the ATO top off container and let it settle before dosing but it would stand to reason if you just keep mixing it in that container then eventually there will be a heavy heavy layer of settlment? So would you actually clean your ato container every time you mix the solution? I would guess not. I thinking about just making the solution in a 5 gallon bucket and siphoning it into my ATO reservoir to avoid the layer at the botton.

 

[arman]

Do you mean that if i mix a new one without taking the remaining settlment it wont cause more precipitation?