Kalk vs 2 part

[hig789]

What are the advantages/disadvantages of either?

Soon I am planning on adding kalk to my top off water. Just seems way easier than hand dosing. And way cheaper than buying all the pumps for 2 part.

I guess pump dosing two part is better for high demand systems? Or is just personal preference?

 

[hybridazn]

Lots of threads recently on this topic. I started one myself not too long ago that has great info and answers your questions

http://reef2reef.com/threads/am-i-crazy-to-consider-switching-to-kalk.207675/

 

[Downbeach]

I believe kalkwasser is a real asset to any system, even if you're using two part or a Ca reactor. I started using kalk in my top off* when my WC's alone, were no longer enough to keep up with the Ca and Alk demands of my system. Eventually, as my system grew, it was no longer enough by itself to keep up, so I started adding a 2 part commercial product, and eventually switched to Randy's DIY formula's.

*I started with 1/2 saturation(1tsp/gal) and evolved into full saturation(2tsp/gal), as the needs increased.

 

[Randy Holmes-Farley]

I compare the pros and cons of all the methods for calcium and alkalinity addition here:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

from it:

Limewater

Limewater (also known by the German term kalkwasser) has been used very successfully by aquarists for decades, and it is the system that I have used exclusively on my aquarium for 19 years. It is comprised of an aqueous solution of calcium and hydroxide ions that can be made by dissolving either quicklime (calcium oxide, CaO) or lime (calcium hydroxide, Ca(OH)2) in fresh water. The only inherent difference between the two is that if you add a molecule of water to quicklime, you get lime, and that a significant amount of heat can be generated when that happens.

CaO + H2O → Ca(OH)2

Quicklime + Water → Lime

Consequently, dissolving quicklime can make the water quite warm, especially if an excess of solids are added. Most hobby companies sell solid calcium hydroxide as “kalkwasser” or some similar name, although the name technically only applies to the solution.

The calcium ions in the solution obviously supply calcium to the tank, and the hydroxide ions supply alkalinity. Hydroxide (OH-) itself provides alkalinity (both by definition and as measured with an alkalinity test), but corals consume alkalinity as bicarbonate, not hydroxide. Fortunately, when limewater is used in a reef tank, it quickly combines with atmospheric and in- tank carbon dioxide (CO2) and bicarbonate (HCO3-) to form bicarbonate and carbonate (CO3–):

OH- + CO2 → HCO3-

OH- + HCO3- → CO3– + H2O

Once in the aquarium at an acceptable pH, there is no concern that the alkalinity provided by limewater is any different than any other carbonate alkalinity supplement. The hydroxide immediately disappears into the bicarbonate/carbonate system. In other words, the amount of hydroxide present in aquarium water is really only a function of pH (regardless of what has been added), and at any pH below 9, it is an insignificant factor in alkalinity tests (much less than 0.1 dKH). Consequently, the fact that alkalinity is initially supplied as hydroxide is not to be viewed as problematic, except as it impacts pH (see below).

The fact that limewater is very basic (the pH is typically above 12) demands that the limewater be added slowly to an aquarium unless very small additions are made. The reason for slow addition is two-fold: to prevent the local pH in the area of the addition from rising too high (slow addition permits more rapid mixing with tank water to reduce the pH), and to prevent the overall tank pH from rising too high (slow addition allows the tank to pull in CO2 from the atmosphere during the slow addition, mitigating the pH rise). Some aquarists advocate rapid addition, and that is acceptable for additions that would add significantly less than 0.5 dKH of alkalinity to the tank, but an addition of 1.4 dKH (0.5 meq/L; the equivalent of adding 1.2% of the tank volume in saturated limewater or 14 grams of solid calcium hydroxide into a 100-gallon tank) drives the pH of the whole tank too high (up by about 0.6 pH units from where ever it started).

Consequently, limewater is most often added slowly, by dripping or slow pumping. Often it is added as the top off water, replacing most or all of the evaporated water. The pumps add cost and complexity to the system, especially if combined with a float valve or switch (I use the latter and a Reef Filler pump).

As mentioned, limewater has a very high pH. This high pH can have significant advantages with respect to impurities present in the lime. Phosphate and many heavy metals will precipitate, either as calcium salts, or as metal oxides and hydroxides. Copper, for example, may accumulate in some aquaria. Copper hydroxide is very insoluble in limewater because of all of the hydroxide present. From an aquarist’s perspective, there will simply be no copper in clear limewater assuming that it has been given a chance to settle out because copper hydroxide is so very insoluble, regardless of whether there is a copper impurity in the calcium hydroxide solid, or in the source water used. Some aquarists get colored residues in limewater systems, and these colors are coming from metal impurities that did not get into the tank.

Another advantage of limewater may be its ability to reduce the phosphate already in the tank water. While it may be as simple as precipitation of calcium phosphate where the high pH, high calcium limewater meets the aquarium water, the mechanism and extent of this effect in typical reef tanks has not been established.

Another important consideration for limewater is the upper limit to the amount that can be added to an aquarium. The solubility limit of calcium hydroxide in fresh water is about 2 level teaspoons per gallon. If an aquarist has a tank near the high end of calcium and alkalinity demand, then replacing all of the evaporated water with saturated limewater may not be adequate to replace the ongoing losses of calcium and alkalinity. There are a couple of tricks to get a little more from the limewater. These are adding fans to increase evaporation, and adding vinegar to increase the solubility of the lime in the limewater (45 mL of vinegar per gallon of limewater will allow three level teaspoons to dissolve instead of just two). Both of these systems have been successfully employed by many aquarists.

Additionally, the use of a small amount of one of the other balanced additive systems (especially the two/three-part additive systems) in conjunction with limewater is often used by aquarists give a little boost to tanks that need a small amount of extra calcium and alkalinity beyond what limewater can supply, without incurring significant capital costs. Likewise, they can be successfully combined with limewater during periods of low evaporation. Unlike some other supplementation schemes, tank salinity will not increase over time through the use of limewater.

The cost of a limewater system can range from very little to quite a lot. If one uses an inexpensive drip system ($20) and bulk sources of lime the cost can be quite low. Bulk calcium hydroxide available to hobbyists sells for less than $2 per pound (maybe much less in a group buy from a large distributor). The cost per thousand milliequivalents (meq) of alkalinity is on the order of $0.15. I realize that this number means nothing to most aquarists, but I’ll use it to permit cost comparisons of very different supplementation schemes, and at the end of the article, I’ll convert it to yearly costs for some typical tanks. Branded hobby and lab grades of calcium hydroxide will be more expensive. A pound of calcium hydroxide from a well-known hobby company costs about $7, or $0.57 per thousand meq of alkalinity.

Of course, dosing pumps can be several hundred dollars, a good float switch can be $50-100, and one needs to get a reservoir as well (often a plastic container like a trash can; I use 44-gallon Rubbermaid Brute trash cans). Depending on the setup, the limewater reservoir can be far from the tank; even in another room or on another floor of the home. A pump like a Reef Filler or Liter Meter pump can be used to send the limewater significant distances, freeing up space around the tank.

Some people use reactors to deliver limewater. These systems automate the delivery of limewater to the tank, and, of course, the costs rise. They consist of a chamber where fresh water enters, is mixed with solid lime, and the fluid limewater exits the system and travels to the tank. They do not permit any additional calcium or alkalinity to be delivered to a tank compared to other limewater delivery methods (assuming that both use saturated limewater), but many claim them to be less hassle than delivery from a still reservoir. Addition of limewater with the simplest drippers may require daily attention, while delivery from a large reservoir may require attention only once every 1-5 weeks, which is about the same as typical limewater reactors. All of the other comments about limewater apply equally well when used with a reactor, a dripper, or a slow pump from a still reservoir (except that the vinegar/limewater combination is technically difficult to use with a limewater reactor).

On the negative side, limewater does have some concerns that don’t apply to most other systems. One is the effect of overdosing. All calcium and alkalinity additives, if added in sufficient overdose, can case abiotic precipitation of calcium carbonate in the tank. Limewater, however, is especially prone to this effect for two reasons. If overdosed, the high pH of the limewater will rapidly convert much of the bicarbonate in the tank to carbonate, increasing the likelihood of precipitating calcium carbonate. Also, addition of solid lime particles can cause local extreme spikes in pH and calcium that nucleate precipitation of calcium carbonate. Consequently, a limewater overdose, and especially the dosing of lime solids, is by far the most frequent cause of “snowstorm” events where calcium carbonate precipitates all through the water column. In some cases, the tank can look like milk. The good news is that this event usually causes no lasting harm to tank inhabitants unless the amount overdosed is exceptionally large, but it is nearly always upsetting to the aquarist. I’ve had it happen numerous times without losing anything.

Another drawback to systems where the limewater dose is tied to evaporation is that the evaporation may change daily or seasonally. I’ve not found that to be problematic in my system, but others who are more concerned about maintaining a very specific alkalinity may have more trouble with this issue. Dosing limewater on a timed pump rather than to match evaporation may eliminate the concern, as long as it doesn’t exceed evaporation rates.

One final note on lime: The high pH of the liquid and the dust hazard of the solid are not to be treated lightly. Inhalation of the dust is to be avoided. Splashing of limewater onto skin is also to be avoided, and should be followed by extensive rinsing with tap water if it happens. Splashing of limewater into the eyes is especially to be avoided, and the use of safety goggles when using large amounts or in situations where exposure is likely is prudent. Extensive and immediate rinsing with tap water, followed by professional help would be advised in the case of eye exposure.

 

[Randy Holmes-Farley]

Two-part Balanced Additive Systems

There are now a plethora of two-part balanced systems for supplementing calcium and alkalinity, as well as DIY recipes that I have published and for which suppliers sell quality DIY ingredients. These are always liquid additives that you add equally to tanks to supplement both calcium and alkalinity. In the DIY version, magnesium is added to the aquarium as a third solution, although it need not be added especially frequently. The rational for this type of product is that the bicarbonate and carbonate that one might like to dose to supplement alkalinity are not readily compatible with the calcium that is also needed. So one portion contains calcium and the other contains the alkalinity. When a DIY is used, the magnesium sulfate in it is not compatible with either part, so it needs its own solution.

In the simplest form, such a system would be provided by any calcium salt at one concentration in one bottle, and a carbonate alkalinity supplement in the other bottle. Within that constraint, manufacturers have a fair amount of room to play. Typically these additives claim go a step further. When the calcium and alkalinity are taken out of the picture, as they will be by calcification in the tank, then the ions that remain are often described as having the same ratios of ions as natural seawater. Assuming that this is true, then the “residue” is simply more salt for the aquarium. Over long periods of time the salinity will build up due to this process (an effect that is quantified below), but there will be no significant buildup of specific ions in the tank.

In order to accomplish this, manufacturers could use a variety of calcium salts in the calcium portion, for example. They could use calcium chloride, calcium sulfate, calcium bromide, and a variety of other similar salts. They could also put magnesium and strontium in this portion as they would not be compatible with the alkalinity component.

The alkalinity portion of these systems is more complicated. As has been shown in other parts of this article, alkalinity can be provided as bicarbonate, carbonate, or hydroxide. I don’t know of any commercial supplements that use hydroxide for a two part system, but the commercial ones do use bicarbonate, carbonate, and mixtures thereof. Consequently the pH varies substantially between brands, and the various brands of these products should not be thought of as identical for this reason, if no other. In order to attain the natural seawater residue, the alkalinity portion could contain sodium bicarbonate or carbonate, potassium bicarbonate or carbonate, lithium bicarbonate or carbonate, etc.

I’ve not seen any independent test of whether these actually produce a residue equivalent to natural seawater, but I’ve seen no particular reason to doubt it, at least for the major ions. When it comes to the trace elements that might concern some reef keepers, it seems unlikely that these products will be any less prone to having uncontrolled levels of trace compounds like copper than are commercial salt mixes, or any other supplement of calcium and alkalinity, but that remains to be determined (at least as far as I know).

One issue that has confused some reef keepers, however, is the presence of trace elements. Assuming that these products are actually formulated with every ion such that a true natural seawater residue remained (let’s call this the “ideal” product), then it will necessarily contain such ions as copper. Since copper is elevated in some reef tanks, and is toxic to many invertebrates, reef keepers have wrongly criticized this method as adding more copper. That’s actually not what would happen. Since these products leave a natural seawater residue, and since copper may be elevated in concentration in many reef tanks relative to seawater, then using these “ideal” products will actually LOWER copper levels because when the increase in salinity is corrected, the copper will drop.

For example:

You have copper in your aquarium at 4 ppb and salinity of S=35.

You add a two part additive that over the course of a month raises salinity to S=36, and raises copper to 4.02 ppb.

Then you correct the salinity back to S=35 by diluting everything in the tank with fresh water, and you get a final copper concentration of 3.9 ppb.

Does this happen in real products and not “ideal” products? I have no idea. But the statement by manufacturers that it contains all ions in natural ratios, including copper, should not be viewed as a concern that it is exacerbating a heavy metal problem.

The rise in salinity of these products over time can be very roughly calculated, though there are several reasons why this calculation is only an estimate. For every 1000 meq of alkalinity added in this fashion (and the matching amount of calcium) these products will deliver on the order of 60 grams of other ions to the tank. In a tank with a low calcification demand (defined later to be 18.3 thousand meq of alkalinity per year in a 100 gallon tank (0.4 dKH/day)) this effect will raise the salinity by 3 ppt per year (compared to a normal salinity of S ~35). In a high demand tank (defined later to be 219 thousand meq of alkalinity per year in a 100 gallon tank (4.4 dKH/day)), the salinity will rise by 35 ppt in a year, or approximately doubling the salinity. Consequently, the salinity should be monitored closely in using these types of additives, especially in a tank with high calcification rates.

Many people have begun to use dosing pumps to deliver these sorts of additives more uniformly across a day/night period with less work by the aquarist. Such pumps can be obtained starting under $100 for each part dosed this way. There is no need to dose the magnesium part this way, since very little is actually required and once a week is plenty often enough.

The costs of these systems vary a bit. The original B-ionic from ESV costs about $34 for 1 gallon of both parts (10,600 meq of alkalinity), or about $3.20 per thousand meq of alkalinity. It has a pH raising effect, similar to my DIY Recipe 1. The B-ionic Bicarbonate version is more expensive, and is necessarily more dilute than is the original because sodium bicarbonate is much less soluble than is sodium carbonate. If your tank pH gets too high using one of them (such as the original B-ionic), then it is reasonable to switch to one that has a smaller pH raising effect (like the bicarbonate B-ionic or my DIY Recipe 2 using baking soda).

The DIY recipes can be far less expensive, depending on what grade of ingredients you use. Buying ingredients from a place such as Bulk Reef Supply will cost roughly $10 per gallon (total cost of all parts, so 1 gallon calcium, 1 gallon alkalinity, and a few cups of magnesium additive), or about $1.40 per thousand meq of alkalinity.

 

[hig789]

I compare the pros and cons of all the methods for calcium and alkalinity addition here:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

from it:

Limewater

Limewater (also known by the German term kalkwasser) has been used very successfully by aquarists for decades, and it is the system that I have used exclusively on my aquarium for 19 years. It is comprised of an aqueous solution of calcium and hydroxide ions that can be made by dissolving either quicklime (calcium oxide, CaO) or lime (calcium hydroxide, Ca(OH)2) in fresh water. The only inherent difference between the two is that if you add a molecule of water to quicklime, you get lime, and that a significant amount of heat can be generated when that happens.

CaO + H2O → Ca(OH)2

Quicklime + Water → Lime

Consequently, dissolving quicklime can make the water quite warm, especially if an excess of solids are added. Most hobby companies sell solid calcium hydroxide as “kalkwasser” or some similar name, although the name technically only applies to the solution.

The calcium ions in the solution obviously supply calcium to the tank, and the hydroxide ions supply alkalinity. Hydroxide (OH-) itself provides alkalinity (both by definition and as measured with an alkalinity test), but corals consume alkalinity as bicarbonate, not hydroxide. Fortunately, when limewater is used in a reef tank, it quickly combines with atmospheric and in- tank carbon dioxide (CO2) and bicarbonate (HCO3-) to form bicarbonate and carbonate (CO3–):

OH- + CO2 → HCO3-

OH- + HCO3- → CO3– + H2O

Once in the aquarium at an acceptable pH, there is no concern that the alkalinity provided by limewater is any different than any other carbonate alkalinity supplement. The hydroxide immediately disappears into the bicarbonate/carbonate system. In other words, the amount of hydroxide present in aquarium water is really only a function of pH (regardless of what has been added), and at any pH below 9, it is an insignificant factor in alkalinity tests (much less than 0.1 dKH). Consequently, the fact that alkalinity is initially supplied as hydroxide is not to be viewed as problematic, except as it impacts pH (see below).

The fact that limewater is very basic (the pH is typically above 12) demands that the limewater be added slowly to an aquarium unless very small additions are made. The reason for slow addition is two-fold: to prevent the local pH in the area of the addition from rising too high (slow addition permits more rapid mixing with tank water to reduce the pH), and to prevent the overall tank pH from rising too high (slow addition allows the tank to pull in CO2 from the atmosphere during the slow addition, mitigating the pH rise). Some aquarists advocate rapid addition, and that is acceptable for additions that would add significantly less than 0.5 dKH of alkalinity to the tank, but an addition of 1.4 dKH (0.5 meq/L; the equivalent of adding 1.2% of the tank volume in saturated limewater or 14 grams of solid calcium hydroxide into a 100-gallon tank) drives the pH of the whole tank too high (up by about 0.6 pH units from where ever it started).

Consequently, limewater is most often added slowly, by dripping or slow pumping. Often it is added as the top off water, replacing most or all of the evaporated water. The pumps add cost and complexity to the system, especially if combined with a float valve or switch (I use the latter and a Reef Filler pump).

As mentioned, limewater has a very high pH. This high pH can have significant advantages with respect to impurities present in the lime. Phosphate and many heavy metals will precipitate, either as calcium salts, or as metal oxides and hydroxides. Copper, for example, may accumulate in some aquaria. Copper hydroxide is very insoluble in limewater because of all of the hydroxide present. From an aquarist’s perspective, there will simply be no copper in clear limewater assuming that it has been given a chance to settle out because copper hydroxide is so very insoluble, regardless of whether there is a copper impurity in the calcium hydroxide solid, or in the source water used. Some aquarists get colored residues in limewater systems, and these colors are coming from metal impurities that did not get into the tank.

Another advantage of limewater may be its ability to reduce the phosphate already in the tank water. While it may be as simple as precipitation of calcium phosphate where the high pH, high calcium limewater meets the aquarium water, the mechanism and extent of this effect in typical reef tanks has not been established.

Another important consideration for limewater is the upper limit to the amount that can be added to an aquarium. The solubility limit of calcium hydroxide in fresh water is about 2 level teaspoons per gallon. If an aquarist has a tank near the high end of calcium and alkalinity demand, then replacing all of the evaporated water with saturated limewater may not be adequate to replace the ongoing losses of calcium and alkalinity. There are a couple of tricks to get a little more from the limewater. These are adding fans to increase evaporation, and adding vinegar to increase the solubility of the lime in the limewater (45 mL of vinegar per gallon of limewater will allow three level teaspoons to dissolve instead of just two). Both of these systems have been successfully employed by many aquarists.

Additionally, the use of a small amount of one of the other balanced additive systems (especially the two/three-part additive systems) in conjunction with limewater is often used by aquarists give a little boost to tanks that need a small amount of extra calcium and alkalinity beyond what limewater can supply, without incurring significant capital costs. Likewise, they can be successfully combined with limewater during periods of low evaporation. Unlike some other supplementation schemes, tank salinity will not increase over time through the use of limewater.

The cost of a limewater system can range from very little to quite a lot. If one uses an inexpensive drip system ($20) and bulk sources of lime the cost can be quite low. Bulk calcium hydroxide available to hobbyists sells for less than $2 per pound (maybe much less in a group buy from a large distributor). The cost per thousand milliequivalents (meq) of alkalinity is on the order of $0.15. I realize that this number means nothing to most aquarists, but I’ll use it to permit cost comparisons of very different supplementation schemes, and at the end of the article, I’ll convert it to yearly costs for some typical tanks. Branded hobby and lab grades of calcium hydroxide will be more expensive. A pound of calcium hydroxide from a well-known hobby company costs about $7, or $0.57 per thousand meq of alkalinity.

Of course, dosing pumps can be several hundred dollars, a good float switch can be $50-100, and one needs to get a reservoir as well (often a plastic container like a trash can; I use 44-gallon Rubbermaid Brute trash cans). Depending on the setup, the limewater reservoir can be far from the tank; even in another room or on another floor of the home. A pump like a Reef Filler or Liter Meter pump can be used to send the limewater significant distances, freeing up space around the tank.

Some people use reactors to deliver limewater. These systems automate the delivery of limewater to the tank, and, of course, the costs rise. They consist of a chamber where fresh water enters, is mixed with solid lime, and the fluid limewater exits the system and travels to the tank. They do not permit any additional calcium or alkalinity to be delivered to a tank compared to other limewater delivery methods (assuming that both use saturated limewater), but many claim them to be less hassle than delivery from a still reservoir. Addition of limewater with the simplest drippers may require daily attention, while delivery from a large reservoir may require attention only once every 1-5 weeks, which is about the same as typical limewater reactors. All of the other comments about limewater apply equally well when used with a reactor, a dripper, or a slow pump from a still reservoir (except that the vinegar/limewater combination is technically difficult to use with a limewater reactor).

On the negative side, limewater does have some concerns that don’t apply to most other systems. One is the effect of overdosing. All calcium and alkalinity additives, if added in sufficient overdose, can case abiotic precipitation of calcium carbonate in the tank. Limewater, however, is especially prone to this effect for two reasons. If overdosed, the high pH of the limewater will rapidly convert much of the bicarbonate in the tank to carbonate, increasing the likelihood of precipitating calcium carbonate. Also, addition of solid lime particles can cause local extreme spikes in pH and calcium that nucleate precipitation of calcium carbonate. Consequently, a limewater overdose, and especially the dosing of lime solids, is by far the most frequent cause of “snowstorm” events where calcium carbonate precipitates all through the water column. In some cases, the tank can look like milk. The good news is that this event usually causes no lasting harm to tank inhabitants unless the amount overdosed is exceptionally large, but it is nearly always upsetting to the aquarist. I’ve had it happen numerous times without losing anything.

Another drawback to systems where the limewater dose is tied to evaporation is that the evaporation may change daily or seasonally. I’ve not found that to be problematic in my system, but others who are more concerned about maintaining a very specific alkalinity may have more trouble with this issue. Dosing limewater on a timed pump rather than to match evaporation may eliminate the concern, as long as it doesn’t exceed evaporation rates.

One final note on lime: The high pH of the liquid and the dust hazard of the solid are not to be treated lightly. Inhalation of the dust is to be avoided. Splashing of limewater onto skin is also to be avoided, and should be followed by extensive rinsing with tap water if it happens. Splashing of limewater into the eyes is especially to be avoided, and the use of safety goggles when using large amounts or in situations where exposure is likely is prudent. Extensive and immediate rinsing with tap water, followed by professional help would be advised in the case of eye exposure.

Thanks Randy One of the few articles I haven't read.

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing. :)

 

[s2nhle]

Great thank you for sharing.

 

[Nano sapiens]

Randy - I have used Kalkwasser exclusively for over 30 years and for half of those years I've wondered if calcification was somehow 'different' using Kalkwasser vs. what would occur in nature.

What got me interested in the subject was Borneman's 'Aquarium Corals: Selection, Husbandry and Natural History' (pg 353) where I noted his reference to the possibility that Kalkwasser use *may* cause a somewhat different method of calcification vs. what occurs in nature. He goes on to say that the significantly higher number of hydroxide ions may act as a 'buffer' of sorts, but not in the same manner as in the ocean where OH- is almost nonexistant. He references an Adey (1998) experiment where corals were put in closed containers and measured for alkalinity depletion and they showed significantly reduced levels of bicarbonate uptake. Granted this is an older book (first copyright 2001), but I have not run into any other references suggesting that Kalkwasser calcification was somehow 'different'. Do you perhaps know if the experiment was somehow flawed or the conclusions drawn were incorrectly attributed specifically to Kalkwasser usage?

I see that you addressed the issue in your Kalkwasser article...perhaps because of previous erroneous assumptions?

"Once in the aquarium at an acceptable pH, there is no concern that the alkalinity provided by limewater is any different than any other carbonate alkalinity supplement. The hydroxide immediately disappears into the bicarbonate/carbonate system. In other words, the amount of hydroxide present in aquarium water is really only a function of pH (regardless of what has been added), and at any pH below 9, it is an insignificant factor in alkalinity tests (much less than 0.1 dKH). Consequently, the fact that alkalinity is initially supplied as hydroxide is not to be viewed as problematic, except as it impacts pH (see below)"

Just wanted to say that your articles are always insightful!

Ralph -

 

[Harold Green]

Very informative. I add kalk water to my ato reservoir as my ro water tends to be low in ph. I alternate daily between adding reef builder and reef advantage calcium to my sump and the mix tends to keep my tank ph where I want it. Not trying to plug reef builder but I've used it alone previously for years with good results in coral and tube worm growth. It may not be as good as some other products but I find it easy to use.

 

[Randy Holmes-Farley]

Randy - I have used Kalkwasser exclusively for over 30 years and for half of those years I've wondered if calcification was somehow 'different' using Kalkwasser vs. what would occur in nature.

What got me interested in the subject was Borneman's 'Aquarium Corals: Selection, Husbandry and Natural History' (pg 353) where I noted his reference to the possibility that Kalkwasser use *may* cause a somewhat different method of calcification vs. what occurs in nature. He goes on to say that the significantly higher number of hydroxide ions may act as a 'buffer' of sorts, but not in the same manner as in the ocean where OH- is almost nonexistant. He references an Adey (1998) experiment where corals were put in closed containers and measured for alkalinity depletion and they showed significantly reduced levels of bicarbonate uptake. Granted this is an older book (first copyright 2001), but I have not run into any other references suggesting that Kalkwasser calcification was somehow 'different'. Do you perhaps know if the experiment was somehow flawed or the conclusions drawn were incorrectly attributed specifically to Kalkwasser usage?

I see that you addressed the issue in your Kalkwasser article...perhaps because of previous erroneous assumptions?

"Once in the aquarium at an acceptable pH, there is no concern that the alkalinity provided by limewater is any different than any other carbonate alkalinity supplement. The hydroxide immediately disappears into the bicarbonate/carbonate system. In other words, the amount of hydroxide present in aquarium water is really only a function of pH (regardless of what has been added), and at any pH below 9, it is an insignificant factor in alkalinity tests (much less than 0.1 dKH). Consequently, the fact that alkalinity is initially supplied as hydroxide is not to be viewed as problematic, except as it impacts pH (see below)"

Just wanted to say that your articles are always insightful!

Ralph -

Thanks. Yes, Eric was uninformed about chemistry when he made those claims above, and yes, those issues are why I wrote that passage. :)

The main thing that is different about limewater is that it usually results in a pH that is higher than if you used almost any other method of calcium and alkalinity addition. Most often, that is probably desirable, unless the pH actually gets too high.

There may also be some calcium carbonate precipitation at the point of addition. Maybe incorporating phosphate into the structure.

 

[Nano sapiens]

Thanks. Yes, Eric was uninformed about chemistry when he made those claims above, and yes, those issues are why I wrote that passage. :)

The main thing that is different about limewater is that it usually results in a pH that is higher than if you used almost any other method of calcium and alkalinity addition. Most often, that is probably desirable, unless the pH actually gets too high.

There may also be some calcium carbonate precipitation at the point of addition. Maybe incorporating phosphate into the structure.

That certainly clears things up! Thanks.

 

[luxauterna]

I have always used two part supplements, but I am strongly considering going with a kalk dripper for this system. I am a little worried about swings while I am away on vacations or weekend trips though.

 

[Harold Green]

In my set up I have a 30 gallon ato tank that feeds the sump. I pour the clear kalk water into the ato tank along with ro water so the ph is only slightly above the dsp tanks ph. That way the ato can run for a week unattended if necessary and I don't have to worry about ph swings from the ato.

 

[luxauterna]

Another thing I definitely need to finally set up (an ATO)

 

[Harold Green]

Wish I had one on my 29g frag tank. It loses a half gallon a day.

 

[s2nhle]

Very good learning information. Thank you for sharing. I have used kalk with dosing pump for awhile now. So far so good.

 

[zemuss]

following

 

[Randy Holmes-Farley]

I have always used two part supplements, but I am strongly considering going with a kalk dripper for this system. I am a little worried about swings while I am away on vacations or weekend trips though.

Because you'd use a dripper that won't last that long?

 

[luxauterna]

Because you'd use a dripper that won't last that long?

Well I was originally considering the dripper method, but now I will be using the ATO method. I still have some reservations for something like a 10 day vacation where the water would need to be replenished by a family member, and I don't want to rely on them for dosing the ATO water with kalk.