General Kalkwasser Mechanism Questions

[Kerbash]

Sup guys,

I'm just looking for some clarity on kalkwasser and how they work and all that, looking to switch over from the 2 part dosing. So from my understanding, the current method to dose kalkwasser is to just add the amount into the ATO system and dose it slowly at night.

1. The reason we cant directly dose kalkwasser into saltwater:

Since it will raise the pH and drive the formation of excess carbonate, driving both calcium and magnesium out of the saltwater solution. So in theory its possible to prevent precipitation and in effect the depletion of Cal if the pH level was managed (By some other thing like acid), which will cause some of the carbonate to form bi carbonate, which is soluble in water. Is this understanding correct?

1. The reason to keep kalkwasser in an air tight container:

We are trying to stop the carbonate from forming from the CO2 in the air which will bind with Cal precipitating CaCO3 and depleting Cal from the solution?

Thanks just curious.

 

[Nano sapiens]

One can actually dose kalk directly to a system, but there's definitely risk involved and it should only be done in quite small amounts. Too much, too fast and you can drive pH too high and create a precipitation event and all the issues that go with that.

IMO/IME, the safest method is to externally produce a clear saturated solution of kalkwasser and use this in the ATO. If the saturated solution is too potent, then an appropriate ratio of the saturated kalkwasser to RO water can be used to keep alkalinity and calcium levels stable. If the saturated kalkwasser solution does not provide sufficient calcium/alkalinity to keep up with the system's demands, one can add an acid (typically vinegar) that will allow a bit more of the kalk to dissolve when mixed with water.

For a more in-depth technical answer, Randy would be the guy

 

[Randy Holmes-Farley]

We should not ever call a powder kalkwasser. That’s the problem of using foreign languages without knowing the meaning. In English it is limewater, lime dissolved in water. In German it is kalk in wasser.

So when you say directly add kalkwasser, that is the way folks always do it. Presumably the intended question is why not dose calcium hydroxide powder directly.
The concerns are the risk of it not dissolving fully before landing on delicate organisms, and local precipitation of calcium carbonate on and near a dissolving calcium hydroxide particle.

Your answer to the second question is correct except it depletes both the alk and calcium when calcium carbonate precipitates.

 

[Nano sapiens]

We should not ever call a powder kalkwasser. That’s the problem of using foreign languages without knowing the meaning. In English it is limewater, lime dissolved in water. In German it is kalk in wasser.

So when you say directly add kalkwasser, that is the way folks always do it. Presumably the intended question is why not dose calcium hydroxide powder directly.
The concerns are the risk of it not dissolving fully before landing on delicate organisms, and local precipitation of calcium carbonate on and near a dissolving calcium hydroxide particle.

Your answer to the second question is correct except it depletes both the alk and calcium when calcium carbonate precipitates.

Thank you, German is my second language and I lived there for many years.

"One can actually dose kalk directly to a system".

I meant exactly this, that one *can* dose kalk powder directly to a reef aquarium (mentioned in one of Sprung/Delbeeks' books), but it is quite risky. A few people on this forum have mentioned that they actually do add kalk this way.

For all other references, I use 'Kalkwasser' (lime and water).

Does this clarify?

 

[Randy Holmes-Farley]

Thank you, German is my second language and I lived there for many years.

"One can actually dose kalk directly to a system".

I meant exactly this, that one *can* dose kalk powder directly to a reef aquarium (mentioned in one of Sprung/Delbeeks' books), but it is quite risky. A few people on this forum have mentioned that they actually do add kalk this way.

For all other references, I use 'Kalkwasser' (lime and water).

Does this clarify?

I understand and agree with you.

My response above on the definition of kalkwasser was intended to the OP who stated:

"The reason we cant directly dose kalkwasser into saltwater:"

 

[Nano sapiens]

I understand and agree with you.

My response above on the definition of kalkwasser was intended to the OP who stated:

"The reason we cant directly dose kalkwasser into saltwater:"

Ahh, I see...all good then

 

[Kerbash]

We should not ever call a powder kalkwasser. That’s the problem of using foreign languages without knowing the meaning. In English it is limewater, lime dissolved in water. In German it is kalk in wasser.

So when you say directly add kalkwasser, that is the way folks always do it. Presumably the intended question is why not dose calcium hydroxide powder directly.
The concerns are the risk of it not dissolving fully before landing on delicate organisms, and local precipitation of calcium carbonate on and near a dissolving calcium hydroxide particle.

Your answer to the second question is correct except it depletes both the alk and calcium when calcium carbonate precipitates.

Hey thanks for the reply,
So some follow up questions.
1. so the main reason we cant does the CaOH powder directly into the tank is mainly because it might land on organism and possibly burn them? What if we dose it in the sump?
2. Also sorry Im a bit confused about the answer to the first question. So the reason that CaCO3 dont normally precipitate out of the SW but only when you add CaOH is because CaOH drives the pH up which drives the concentration of CaCO3 right? So the only reason CaCO3 precipitate is due to the high pH caused by CaOH?

 

[Randy Holmes-Farley]

Hey thanks for the reply,
So some follow up questions.
1. so the main reason we cant does the CaOH powder directly into the tank is mainly because it might land on organism and possibly burn them? What if we dose it in the sump?
2. Also sorry Im a bit confused about the answer to the first question. So the reason that CaCO3 dont normally precipitate out of the SW but only when you add CaOH is because CaOH drives the pH up which drives the concentration of CaCO3 right? So the only reason CaCO3 precipitate is due to the high pH caused by CaOH?

1. The concern is both reasons I mentioned. Burning organisms and precipitation. Plus the difficulty of spreading out the dose.

2. Precipitation of calcium carbonate can happen by any sufficiently high increase in calcium, alkalinity, or pH. Solid calcium hydroxide does all of these near a solid particle of undissolved material. The same chemicals predissolved in ro/di do it to a smaller extent.

Does either if these mean you cannot add particulates? No. It means you must recognize what may happen and be sure it doesn’t happen too much.

Dosing an air and moisture sensitive powder is also technically challenging to spread out the dosing over the course of a day, which one generally needs to do to prevent huge pH spikes.

 

[Kerbash]

1. The concern is both reasons I mentioned. Burning organisms and precipitation. Plus the difficulty of spreading out the dose.

2. Precipitation of calcium carbonate can happen by any sufficiently high increase in calcium, alkalinity, or pH. Solid calcium hydroxide does all of these near a solid particle of undissolved material. The same chemicals predissolved in ro/di do it to a smaller extent.

Does either if these mean you cannot add particulates? No. It means you must recognize what may happen and be sure it doesn’t happen too much.

Dosing an air and moisture sensitive powder is also technically challenging to spread out the dosing over the course of a day, which one generally needs to do to prevent huge pH spikes.

Ahh ok thank u soo much!

 

[NabberNate]

Late to the party on this thread. I have about 180 gallon of water in my system and I evaporate about 10 gallons a week. I'm running all of that replacement ato water through a kalkwasser stirrer and I'm not maintaining alk or calcium. I have a small xenia patch otherwise just a ton of corraline covered rock.

What gives? Is this normal? Is my evaporation low? Maybe I'm overfeeding? My ph is about 8.4 by the way. My kalk bag upon shipment was not tightly sealed perhaps it lost some potency?

I was hoping to be able to dose with just the kalkwasser but apparently not. Looking for your thoughts and suggestions. Thanks!

 

[Randy Holmes-Farley]

Late to the party on this thread. I have about 180 gallon of water in my system and I evaporate about 10 gallons a week. I'm running all of that replacement ato water through a kalkwasser stirrer and I'm not maintaining alk or calcium. I have a small xenia patch otherwise just a ton of corraline covered rock.

What gives? Is this normal? Is my evaporation low? Maybe I'm overfeeding? My ph is about 8.4 by the way. My kalk bag upon shipment was not tightly sealed perhaps it lost some potency?

I was hoping to be able to dose with just the kalkwasser but apparently not. Looking for your thoughts and suggestions. Thanks!

A primary drawback to limewater (kalkwasser) is the limitation on how much can be delivered due to solubility limitations in the dosing solution, and in your case that may be confounded by the fact that many kalk reactors deliver less than saturated limewater.

Even if your rector saturated the solution, you are only delivering only about 1 dKH per day. it may just not be enough. A soft coral tank with good coralline can use 2 dKH per day.

Is there any evidence of excessive calcium carbonate precipitation in the tank, such as hard sand?

Have you ever tried to measure the potency of the limewater (preferably by conductivity, but pH can give a crude guide if done properly).

 

[NabberNate]

Thanks Randy. Are those little white dots on the back glass an example of calcium carbonite precipitation? I don't have hard sand but I do have those.

I'm running the stirrer 6 times a day for 5 minutes. Perhaps running it a few more times might help? Would increasing surface water agitation help create more evaporation?

I'll check the ph of the kalkwasser solution and report back. Attached is also a picture of the tank for reference.

Ultimately if this is normal and most people are going to need more alk/calcium than just a kalkwasser stirrer can provide I'll just plan for some sort of automation of the 2 part dosing.

Thanks...

 

[Randy Holmes-Farley]

I can't tell from the photo, but an organism is more likely than precipitation.

 

[NabberNate]

The picture is just too show the amount of coralline algae for reference of how much alk / calcium uptake might be occurring. The white dots in my sump are from a while ago and my tank hasn't been stable (I'm still getting my bearings) so let's ignore. What might excessive precipitation mean anyway?

Ph of kalkwasser solution read 10.5 on my ghl probe but I suspect that is the upper limit. I might get a few test strips to measure.

 

[tgafish]

Dosing an air and moisture sensitive powder is also technically challenging to spread out the dosing over the course of a day, which one generally needs to do to prevent huge pH spikes.

Randy what do you consider as huge pH spikes? My mixed reef system varies from 8.2 to 8.5 on some days. My kalkwasser is introduced via ATO through an Avast kalk stirrer. Thanks

 

[Randy Holmes-Farley]

Randy what do you consider as huge pH spikes? My mixed reef system varies from 8.2 to 8.5 on some days. My kalkwasser is introduced via ATO through an Avast kalk stirrer. Thanks

My concern is not the daily swing, which is natural and happens in all tanks and in the ocean, but the height of the ph peak (and, when not dosing, the low). I'd try to keep the peak below 8.6 (at least after it mixes in well) or else there's more risk of excessive precipitation of calcium carbonate.

 

[Randy Holmes-Farley]

What might excessive precipitation mean anyway?

More alk dosed than is reasonable, seized up pumps, hardened sand. excessively fast coating of heaters.

To test kalkwasser potency by pH you measure a true saturated solution (2 teaspoons in a cup of ro/di. That is about 12.54 at 25 deg C, but it doesn't really matter what it reads as long as its close. Then measure the effluent. A drop of 0.3 pH units compared to the saturated solution is a 50% drop in potency.

 

[NabberNate]

Just did some research and my ghl ph probe maxes out at 10.5 and test strips will not be accurate enough to measure the difference. I'll have to find another probe (suggestions?) to perform this but in the meanwhile I'll have the stirrer run more frequently at night and see if there is a difference. Thanks

 

[nereefpat]

The picture is just too show the amount of coralline algae for reference of how much alk / calcium uptake might be occurring.

That's a ton of coralline algae. That may be part of the 'problem.' Evaporation of about 1.4 gallons a day in a 180 is a little low as well.

What is your alk sitting at, and where do you want it?

 

[NabberNate]

I kind of figured it was alot as I look at pictures of other reef tanks. Not sure why I am so lucky perhaps because I don't have much else in the tank to compete? It's a 150 tank but 75 sump so I'm estimating 180 total water volume.

I try to keep my alk between 9 and 10 but this is a combination of the kalk stirrer and manual dosing. Ph is between 8.4 and 8.5 after the manual dosing.