Kalkwasser (Calcium Hydroxide)

[Aqua Splendor]

Hello, I'm trying to understand a certain situation with one of my tank.
I switched to a Calcium Hydroxide, 2ml for 1L of water

My PH since I've switched hasn't changed, I was expecting to see a difference but nothing.
I notice It took a ton of dosing to get back the calcium.

At one point I said... **** it, let's pour the dosing bottle in the tank.
And yet... to my surprise again, nothing really happen.

The calcium level tested with Salifert (*and also for the ph) is 450, I was expecting a very higher number for my "mistake" but nothing...

I don't understand what's going on, corals are fine.

I notice the solution doesn't mix well with water but that was expected and I have a white powder on the bottom of the glass that I avoid siphoning with the doser.

I'm confused, I need reaction

 

[arking_mark]

What is 2ml of Calcium Hydroxide? Is this a pre-made liquid? If so what brand?

 

[Aqua Splendor]

What is 2ml of Calcium Hydroxide? Is this a pre-made liquid? If so what brand?

2gram, powder, SR Aquatiks, pure Calcium hydroxide

 

[Nano sapiens]

Hmm, so are you perhaps doing '2ml of the saturated kalkwasser liquid to 1 liter of water'?

Per their instructions (typical for any Kalkwasser):

Recommended Dosage: 5-10 ml or 1 or 2 teaspoons makes or can be used for 1 gallon of high quality calcium supplement

Instructions for use: Add 5-10 ml or 1-2 teaspoons of Calcium Hydroxide to a clean, dry 1 gallon container. Fill the container about ¾ full with RO/DI or filtered water; shake vigorously for about 2 minutes. Fill the remaining portion of the container and let sit overnight before adding to the aquarium. For best results, drip supplement slowly into the sump of the aquarium. Never add the powder or residual Calcium Hydroxide to the aquarium. Use only the clear water that is in the container after settling.

I've been using Kalkwasser for 30+ years and here's how I do it. Take 2 tsp. of the dry calcium hydroxide powder (aka 'kalk') and add it to 1 gallon of RO water in a container that can be sealed from air. Stir vigorously for ~2 minutes, seal the container and let it sit undisturbed for at least 24 hours (the solution should be relatively clear before using, and 2-3 days is usually how long I let mine sit). Carefully siphon off the clear saturated kalkwasser solution (this is what you'll use to add to your reef aquarium), leaving all the residue in the bottom of the container (either seal the container again as is, or add fresh RO water and another 1+ tsp kalk powder and seal to start the next batch).

If you know how much alkalinity your aquarium uses, you can use an online calculator to determine how much saturated kalkwasser you'll need:

Kalk Contribution Calculator

Aquarium calculator; Estimate the contribution of a kalk solution towards the calcium and alkalinity of a system.

www.hamzasreef.com

I mix the saturated kalkwasser solution with RO water in whatever ratio is needed to maintain a steady alkalinity for my system (currently 30% kalkwasser/70% RO). Since kalkwasser is a 'balanced solution' (with a set alkalinity to calcium ratio that happens to be the same ratio used by a reef system with calcifying organisms) if enough saturated kalkwasser is used to keep alkalinity levels stable, calcium will stay stable, too, for a long while (there is a slight increasing level of calcium over the long term (months), but I wouldn't worry about that at this point as it can be easily addressed later).

Randy's Kalkwasser article is very helpful:

http://reefkeeping.com/issues/2005-01/rhf/index.htm

 

[Hermie]

What kind of changes are you expecting?

I'm dosing full saturated kalkwasser to my tank to replace all evaporation water, which is the maximum and the tank can even use more alkalinity if I dose other products.

What is your tank using up?
For me, I mix hypersaturation levels of calcium hydroxide with RODI, so more kalk than needed to reach saturation, since as you said, there is some precipitation.

 

[Aqua Splendor]

I'm looking for a change of PH, and a raise of calcium more... sudden

When you say full saturated kalkwasser, what does it mean exactly? Is it possible to visually identify this?
It seems no matter the quantity of powder vs water, there will always be precipitation at the bottom, so I'm having trouble understanding what mean saturation and oversaturation

Are you asking how much calcium my tank is using et alkalinity?

Calcium, idk, I just dump a tiny bit of calcium at times once a month or twice to correct. (...)
for Alk, I use the red sea all powder, 40g for 2L solution and dosing hmm 30ml each day (it fluctuate every week a little bit)

For now I'm testing a way to raise my calcium and increasing considerably the PH compare to what I use before and I thought Calcium Hydroxide was the perfect solution, but... not much reaction.

That being said, I went on the safe side for mixing, by not adding too much powder to the water, I wonder if my problem of no reaction in my tank is due to the low concentration. at the same time my calcium level at the moment is slightly over what I want (looking for 440, its 450 right now)

 

[Nano sapiens]

I'm looking for a change of PH, and a raise of calcium more... sudden

When you say full saturated kalkwasser, what does it mean exactly? Is it possible to visually identify this?
It seems no matter the quantity of powder vs water, there will always be precipitation at the bottom, so I'm having trouble understanding what mean saturation and oversaturation

Are you asking how much calcium my tank is using et alkalinity?

Calcium, idk, I just dump a tiny bit of calcium at times once a month or twice to correct. (...)
for Alk, I use the red sea all powder, 40g for 2L solution and dosing hmm 30ml each day (it fluctuate every week a little bit)

For now I'm testing a way to raise my calcium and increasing considerably the PH compare to what I use before and I thought Calcium Hydroxide was the perfect solution, but... not much reaction.

That being said, I went on the safe side for mixing, by not adding too much powder to the water, I wonder if my problem of no reaction in my tank is due to the low concentration. at the same time my calcium level at the moment is slightly over what I want (looking for 440, its 450 right now)

Seems you might be trying to use kalkwasser too specifically just to raise pH.

Adding 2 tsps of kalk powder to 1 gallon of RO water automatically results in a saturated kalkwasser solution.

Kalkwasser is used to maintain alkalinity, calcium and pH. It's not used to raise alk & cal quickly since doing so will cause pH to rise quickly to a dangerous level. Reef aquariums that use kalkwasser will typically run pH in the 8.1-8.4 range. In a tank with moderate to low numbers of calcifying animals, it's usually enough all by itself to sustain alk and cal. In aquariums with high coral/coralline cover it may not be enough to maintain levels (even at 100% saturated kalkwasser), but it can be enhanced with vinegar or other methods (such as '2-part') in addition to the 100% kalkwasser.

 

[arking_mark]

If you are dosing saturated Kalkwasser, you should see a bump in pH. I'm dosing my 400L tank with 3ml/min which is about 3600ml per day and 1dKH replacement for my tank. I'm able to boost my pH from 7.9 to about 8.14 with kalkwasser alone.

Just remember, if you are using a Skimmer, that will quickly push you to equilibrium with the air it intakes. So if your natural equilibrium with higher CO2 house air is 7.9 (my house) this will quickly counteract the boosting effects of kalkwasser.

 

[Steven Garland]

Also,if you are using a skimmer,think about introducing a co2 scrubber. BRS has them,with reactor and media I think its under $50 for everythinf you need.

It will help keep ph elevated too. I have struggled with a ph of 7.6-8 since my tank has been cycled. I also can't keep any level of nitrates in my,besides 0ppm ‍ soo...

 

[Hermie]

Kalkwasser is not a total solution to pH problems because the pH boost is an "additional benefit" of using it. The purpose of kalk is to boost Alkalinity and Calcium. So if you want to boost pH specifically, I'd not look at kalk alone. It's a temporary boost, in other words. If pH is your problem find another way to raise it as well, besides kalkwasser. If Alkalinity and calcium is your problem, then kalk can be your solution. Sorry I can't repeat the science behind what I'm saying, it has to do with how kalk is broken down and CO2 in the air vs the tank water.

 

[Aqua Splendor]

I'm very very confused, I read contradiction with different messages I'm receiving elsewhere too.

Calcium hydroxide should, in theory, do 2 things:
- Raise PH (Hydroxide?)
- Raise Calcium

Yes or No? (is it possible to ask a yes and no in this situation?)

(it confuse me with the theory of "maintaining Alk/Cal/PH")

Just remember, if you are using a Skimmer, that will quickly push you to equilibrium with the air it intakes. So if your natural equilibrium with higher CO2 house air is 7.9 (my house) this will quickly counteract the boosting effects of kalkwasser.

So the reason why my PH doesn't move is because of the air exchange?
My CO2 level at the moment of the test was around 650 ppm

I have a feeling this is the answer to the problem I encounter...
So the Hydroxyde when in water and in contact with Carbon Dioxide will for Bicarbonate, and that Bicarbonate is bringing down my PH.

During a moment in my test, I had a feeling my PH went even down but wasn't sure since I tested the PH during the morning which is usually lower, but it was lower than before... hmmm My windows are open at the moments constant air flow from outside (not during winter where my co2 lvl can raise to 1500ppm ish)

But it's weird, when I said f*** it let's poor a tons of solution directly in the tank, I should have seen a drastic change of PH no?



At the end my only goal is to raise ph from 8 ish to 8.3 via only dosing pump

 

[arking_mark]

I'm very very confused, I read contradiction with different messages I'm receiving elsewhere too.

Calcium hydroxide should, in theory, do 2 things:
- Raise PH (Hydroxide?)
- Raise Calcium

Yes or No? (is it possible to ask a yes and no in this situation?)

(it confuse me with the theory of "maintaining Alk/Cal/PH")



So the reason why my PH doesn't move is because of the air exchange?
My CO2 level at the moment of the test was around 650 ppm

I have a feeling this is the answer to the problem I encounter...
So the Hydroxyde when in water and in contact with Carbon Dioxide will for Bicarbonate, and that Bicarbonate is bringing down my PH.

During a moment in my test, I had a feeling my PH went even down but wasn't sure since I tested the PH during the morning which is usually lower, but it was lower than before... hmmm My windows are open at the moments constant air flow from outside (not during winter where my co2 lvl can raise to 1500ppm ish)

But it's weird, when I said f*** it let's poor a tons of solution directly in the tank, I should have seen a drastic change of PH no?



At the end my only goal is to raise ph from 8 ish to 8.3 via only dosing pump

A couple of thoughts here.:
1. Calcium Hydroxide is for dosing balanced Alk/Ca. A side effect is adding pH boost as H get consumed in the process.
2. Dumping saturated Kalkwasser would definitely spike your tank and potentially have negative consequences
3. If you spiked your tank and saw no increase in pH, I would question your pH meter/test.

 

[Nano sapiens]

I'm very very confused, I read contradiction with different messages I'm receiving elsewhere too.

In that case, as I mentioned previously, read and understand this:

http://www.reefkeeping.com/issues/2005-01/rhf/

Randy homes-Farley is a very well known and respected chemist that also happens to enjoy reef aquariums.

 

[Aqua Splendor]

I've read multiple time this article and another one but, I just don't understand.
There's a void of information I can't seem to find. And in practice, I have different results from what I should expect.


Let's take an example:

I have a 120L aquarium, I'm dosing Alkalinity, with Red Sea powder (which are not providing any detail information , and I'm going to switch to something else )

I take 20gram of powder and incorporate into 1L of RO/DI water.

From that I use 40ml every day.

Calcium overtime diminish, PH varies between 7.8 to 8.1

Alk/Mag are relatively stable.

Now I take 2gram of Calcium Hydroxide for 1L of RODI water

I avoid sucking the milky powder at the bottom and only dose the saturated solution, let's say 300ml in one day

Calcium is raising slowly, this parameter seems to be the one that tells me what is the limit of what I can dose. When I reach 450ppm of calcium I stop.

PH seems to not be affected whatever the quantity I put (I'm retesting again at the moment)
--> I tried a new PH prob, different value but same constant, no PH change.

 

[Nano sapiens]

I've read multiple time this article and another one but, I just don't understand.
There's a void of information I can't seem to find. And in practice, I have different results from what I should expect.


Let's take an example:

I have a 120L aquarium, I'm dosing Alkalinity, with Red Sea powder (which are not providing any detail information , and I'm going to switch to something else )

I take 20gram of powder and incorporate into 1L of RO/DI water.

From that I use 40ml every day.

Calcium overtime diminish, PH varies between 7.8 to 8.1

Alk/Mag are relatively stable.

Now I take 2gram of Calcium Hydroxide for 1L of RODI water

I avoid sucking the milky powder at the bottom and only dose the saturated solution, let's say 300ml in one day

Calcium is raising slowly, this parameter seems to be the one that tells me what is the limit of what I can dose. When I reach 450ppm of calcium I stop.

PH seems to not be affected whatever the quantity I put (I'm retesting again at the moment)
--> I tried a new PH prob, different value but same constant, no PH change.

Ok, let's try to straighten this out

1. STOP dosing alkalinity with Red Sea powder (kalkwasser, when properly dosed, will do that for you!)
2. Ignore calcium for now and concentrate on maintaining your alkalinity with just the kalkwasser additions.
3. Once you are able to maintain a stable alkalinity (at the level you want), test your calcium level.
4. If the calcium level is good, then simply continue with the kalkwasser.
5. IF calcium is too high, use a little less saturated kalkwasser and makeup any alkalinity deficit by using some of your Red Sea alkalinity product until the calcium level drops to where you want it...then resume using ONLY kalkwasser at the amount that keeps alkalinity stable at the level you prefer.
6. IF calcium is too low, add a calcium specific product (something like Sea Chem's 'Reef Advantage Calcium') to raise only calcium while continuing to keep alkalinity stable using kalkwasser. Once calcium levels have risen to where you want them, then resume using ONLY kalkwasser at the amount that keeps alkalinity stable at the level you prefer.

As you can see above, tune the amount of kalkwasser your system needs by only using alkalinity testing to achieve a stable reading at whatever level you are shooting for (the specifics of why we see alkalinity levels fluctuate much more than calcium levels has to do with the fact that this is a ratio).


Possible Adjustments:

When using just kalkwasser alone and you are keeping the alkalinity level stable at your preferred level, calcium will naturally be there in the correct ratio for a reef aquarium. You only need to adjust alkalinity and calcium separately if your system is 'out of balance' in respect to these two elements.

Let's look at a few possible 'out of balance' examples:

1. Alkalinity is low at 6 dkh, but calcium is at your preferred level of 430 ppm
2. Alkalinity is okay at 9 dKh, which is your preferred target level, but calcium is at low at 350 ppm
3. Both alkalinity and calcium are high
4. Both alkalinity and calcium are low

By manipulation using an alkalinity enchancing product, a calcium enhancing product or the amount of saturated kalkwasser used, you can manipulate any of the above examples to balance the alkalinity and calcium levels.


pH

When using kalkwasser, pH will be whatever it is for your system (each is slightly different due to a number of different factors). In a typical reef aquarium, kalkwasser is known to keep pH at a somewhat higher level than if it weren't used at all.

I hope that helps.

 

[arking_mark]

By my calculation, adding 300ml of saturated Kalkwasser to your 120L tank should have the following impact:
Alk increase = 0.31dKH
Ca increase = 2.19ppm
pH increase = ?? @Randy Holmes-Farley

 

[Aqua Splendor]

Ok, let's try to straighten this out

1. STOP dosing alkalinity with Red Sea powder (kalkwasser, when properly dosed, will do that for you!)
2. Ignore calcium for now and concentrate on maintaining your alkalinity with just the kalkwasser additions.
3. Once you are able to maintain a stable alkalinity (at the level you want), test your calcium level.
4. IF calcium is too high, use a little less saturated kalkwasser and makeup any alkalinity deficit by using some of your Red Sea alkalinity product until the calcium level drops to where you want it...then resume using ONLY kalkwasser to maintain alkalinity again.
5. IF calcium is too low, add a calcium specific product (something like Sea Chem's 'Reef Advantage Calcium') to raise only calcium while continuing to keep alkalinity stable using kalkwasser. Once calcium levels have risen to where you want them, then resume using ONLY kalkwasser at the amount that keeps alkalinity stable at the level you prefer.

As you can see above, tune the amount of kalkwasser your system needs by only using alkalinity testing to achieve a stable reading at whatever level you are shooting for (the specifics of why we see alkalinity levels fluctuate much more than calcium levels has to do with the fact that this is a ratio).


Possible Adjustments:

When using just kalkwasser alone and you are keeping the alkalinity level stable at your preferred level, calcium will naturally be there in the correct ratio for a reef aquarium. You only need to adjust alkalinity and calcium separately if your system is 'out of balance' in respect to these two elements.

Let's look at a few possible 'out of balance' examples:

1. Alkalinity is at 9 dKh, which is your preferred target level, but calcium is at low at 350 ppm.
2. Alkalinity is low at 6 dkh, but calcium is at your preferred level of 430 ppm)
3. Both alkalinity and calcium are low (add more saturated kalkwasser)
4. Both alkalinity and calcium are high (reduce the amount of saturated kalkwasser)

pH will be whatever it is for your system (each is slightly different due to a number of different factors). In a typical reef aquarium, kalkwasser is known to keep pH at a slightly higher level than if it weren't used at all.

I hope that helps.

Love this reply a lot, thank you very much.

Now if I say my alkalinity doesn't move when adding calcium hydroxide... that ... is... strange no?

By my calculation, adding 300ml of saturated Kalkwasser to your 120L tank should have the following impact:
Alk increase = 0.31dKH
Ca increase = 2.19ppm
pH increase = ?? @Randy Holmes-Farley

This is very interesting... maybe it's part of the problem?
But just like I mention in this reply, I didn't feel like my Alkalinity has changed. (0.31 dkh = around 5-6ppm)

At least it's within the marge of error of my test kit.



At the same time... if this is actually the problem, low concentration... and I'm already dropping 300ml of solution every day... this would start to be higher than my evaporation... uh

So ... a question:
The solution above the milky powder, is it FULLY saturated? From what I understood, it's not and some people add vinegar. And adding vinegar will create other problem that I would prefer to avoid, hmmm

What am I doing wrong hmm

 

[arking_mark]

Love this reply a lot, thank you very much.

Now if I say my alkalinity doesn't move when adding calcium hydroxide... that ... is... strange no?



This is very interesting... maybe it's part of the problem?
But just like I mention in this reply, I didn't feel like my Alkalinity has changed. (0.31 dkh = around 5-6ppm)

At least it's within the marge of error of my test kit.



At the same time... if this is actually the problem, low concentration... and I'm already dropping 300ml of solution every day... this would start to be higher than my evaporation... uh

So ... a question:
The solution above the milky powder, is it FULLY saturated? From what I understood, it's not and some people add vinegar. And adding vinegar will create other problem that I would prefer to avoid, hmmm

What am I doing wrong hmm

If mixed properly, it's fully saturated. Adding vinegar allows one to bump up the saturation levels.

 

[Nano sapiens]

Love this reply a lot, thank you very much.

Now if I say my alkalinity doesn't move when adding calcium hydroxide... that ... is... strange no?

The only way I can see this happening is:

1. The system is using up alkalinity at the same amount as is being added via kalkwasser
2. The amount of saturated kalkwasser being added is too small to register on a test kit.

 

[Nano sapiens]

At the same time... if this is actually the problem, low concentration... and I'm already dropping 300ml of solution every day... this would start to be higher than my evaporation... uh

What is your current alkalinity level? Is it low? Kalkwasser is used to MAINTAIN alkalinity and calcium levels, it is not typically used to bring them up (unless you are VERY patient). You first want to bring your alkalinity and calcium up to the levels that you want using alkalinity & calcium products, then use kalkwasser to maintain those levels.

Let me ask you this. Do you have a closed system (enclosed hood, lids on sump, etc.) that limits evaporation? Just an FYI that some people have to resort to using fans to increase evaporation when using kalkwasser in a top-off system. Some also use a drip-system which is independent of the evaporation rate.