Kalkwasser (Calcium Hydroxide)

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My aquarium consumes indeed lot of alk so, ... this could explain the test kit situation, indeed.
the first time I tested the calcium hydroxide, my alk was indeed low, I was scared it would raise up a lot.

but on my second test my alk was where it was supposed to be. but didn't notice alk increasing with Kalk (which could be the consumption rate like you mentioned)

It's a AIO aquarium, no hood (mesh net), old habit to have all my tank in contact with air (exchange).
it's on autopilot, I don't touch it much honestly.

20210419_174622.jpg

(let's not talk about hair algae ... ph ahem, atchoum.)
 

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Ok, I think you got it. Just keep checking your alk regularly and adjust your saturated kalkwasser amount (when necessary) to keep it stable.

IME/IMO, kalkwasser can really benefit a reef aquarium, especially if it has chronic low pH and/or chronic high phosphate. Takes a bit of getting used to and not quite as convenient as some of the other alk/ca products (although it is much cheaper), but well worth the effort.
 
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Will quote a reply I got from FB and hope this will help other people if they search:

Ryan Batcheller - BRStv

If it didn’t raise the ph one of these things is happening
1) you are not adding enough powder to the water. Two teaspoons per gallon of water is the max .
2) it got mixed too long and didn’t have a lid so the solution got depleted.
3) you are not dosing enough.
4) testing error. Cheep test kit rather than a probe.
5) bad kalkwasser. Never heard of this so rare to the extreme.

I have a feeling you're on point, but also a combination of other factors. I'm currently running another batch, I need to wait.

1) I strongly believe this was the case indeed, my new batch is 10ml for 1L (it should have been 8ml of powder, for the ratio you mention, little mistake, but maybe going a bit over I will notice something at least during my next experiment (?))
2) Not the case for this

3) Yes, in combination with concentration.

4) Yes! I was using the Salifert PH test kit. Turn out, it's too hard reading or just inaccurate/not precise. The variation of PH still valid but, with a PH prob, I got values that make more sense. Going from 7.5 to 8

5) Can't say, other than the bag was on the shelf for a very long time.

But here some interesting point:

- When I tested my PH, (and alk) I waited a couple of hours, The amount of "dosing" I added got consume during that period (Low concentration again probably) so that's why I got confused.
Now with the prob with live data, I did notice a rise of ph, tiny, but noticeable, the test kit was inappropriate for the experiment.

- I read on wiki that water solution in the bottle will reach a maximum of 12.4 pH not 12pH from what other people mentioned or maybe article*(?). So that indicates again towards that low concentration.

- I did notice after leaving the bottle, more powder vanished. Which again probably indicates the low concentration. And maybe the CO2 getting in after some close/open caps(?) (Not sure)
Also this time I'm using a clear and Glass Bottle. This is fun, been a couple of months without experiments!

20210421_134241.jpg
 

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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:


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
The residue at the bottom you incorrectly instruct people to dispose of is calcium carbonate.

By dumping it you are removing a major calcium component of the mix. Calcium hydroxide doesnt have much soluable calcium to begin with so you are wasting a lot of it.

Pretty much all substrate, LR, and coral skeletons are made of calcium carbonate. Not sure why you think the calcium carbonate formed by mixing calcium hydroxide is 'evil.

Its akin to making kool-aid, not bothering to mix mix it, and dumping the residue down the drain. Kalk stirrers exist for a reason.
 

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The residue at the bottom you incorrectly instruct people to dispose of is calcium carbonate.

By dumping it you are removing a major calcium component of the mix. Calcium hydroxide doesnt have much soluable calcium to begin with so you are wasting a lot of it.

Pretty much all substrate, LR, and coral skeletons are made of calcium carbonate. Not sure why you think the calcium carbonate formed by mixing calcium hydroxide is 'evil.

Its akin to making kool-aid, not bothering to mix mix it, and dumping the residue down the drain. Kalk stirrers exist for a reason.

Perhaps it's not clear on my post, but the instructions (including disposing of kalkwasser residue) is from the product manufacturer (SR Aquatiks), not me, which is in response to the kalk product that the OP is using:

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.


The manufacturer is saying don't dump raw kalk or the left-over kalk residue directly into the aquarium itself.

Personally, I reuse any residual left-over kalk for ~4-5 times each time I make a new batch of saturated kalkwasser before tossing it and starting with completely fresh kalk powder. As you noted, it makes economical sense to get the most out of the kalk that you can.
 
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Nano sapiens

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Perhaps it's not clear to you on my post, but the instructions (including disposing of kalkwasser residue) is from the OP's product, not me:

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.


The manufacturer is saying is don't dump raw kalk or the left-over kalk residue directly into the aquarium itself.

Personally, I reuse any residual left-over kalk for ~4-5 times each time I make a new batch of saturated kalkwasser. As you noted, it makes economical sense to get the most out of the kalk that you can.
 

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

Not really.

If you add 1 dKH of alkalinity and the demand is 1 dKH per day, then alk won't rise when measured the next day.

Demand RISES when you boost the pH.

Hydroxide addition boosts pH whether you measure it to or not. If you measure pH hours later after dosing, you may see no rise because it has dissipated.

Raising the alk by 1.4 dKH with hydroxide will boost pH by about 0.6 to 0.7 pH units instantly. A 0.3 dKH boost has a very small pH effect: about 0.1 pH unit if added instantly.

Added more slowly, the pH rise is lessened as the tank pulls in CO2 which lowers the pH again.
 

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5) Can't say, other than the bag was on the shelf for a very long time.

Get new material. It is ruined if CO2 enters it, making it into (useless) calcium carbonate.
 
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How can you tell when you reach the full saturation of the solution in the bottle?

When you get 12.4 pH?
And/or
When you see deposit on the bottom?

The reason why I avoid putting it in Auto Top Off reservoir is that I'm afraid of the residue it leaves over time, especially on a cheap tiny pump (XP Aqua)
Am I still right to be afraid or its worth it and just use vinegar/citric acid to rinse the material after X time?


I think I was just not very prepare mentally to see the amount of liquid you have to dose, now that I'm using it I understand why people say X Y Z. Theory and Pratice are two different things...
Especially when I was using the Carbocalcium powder from Tropic Marin which last me forever

Thank you!
 

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How can you tell when you reach the full saturation of the solution in the bottle?

When you get 12.4 pH?
And/or
When you see deposit on the bottom?

The reason why I avoid putting it in Auto Top Off reservoir is that I'm afraid of the residue it leaves over time, especially on a cheap tiny pump (XP Aqua)
Am I still right to be afraid or its worth it and just use vinegar/citric acid to rinse the material after X time?


I think I was just not very prepare mentally to see the amount of liquid you have to dose, now that I'm using it I understand why people say X Y Z. Theory and Pratice are two different things...
Especially when I was using the Carbocalcium powder from Tropic Marin which last me forever

Thank you!

If you have a conductivity meter, that's the best way. ~10.3 mS/cm at 25 deg C is saturation, and potency declines linearally with conductivity.

pH is a crude measure. Make a true saturated solution (say, 2 tablespoons in a cup of RO/DI). Should be about 12.54 at 25 deg C (higher pH at lower temp). But do not rely on your calibration to be accurate in this range.

Take that reading, whatever it is, and then measure the pH of your solution you want to measure potency. A drop of 0.1 pH unit from the saturated solution is about a 20% drop in potency (80% potent) and a drop of 0.3 pH units is 50% potent.

This has more:
 
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Alright, so I've done a couple of experiments, and well... the results are just not here with pH.

- I was able to get higher pH inside of the bottle, but it's often around 12.1

- From that I had some deposit on the bottom, once the liquid was use for the aquarium I refill with water and got almost the same pH (12)

- My calcium finally dropped at some point which was a limiting factor at the beginning

- Unfortunately, I reach the maximum of water I can add to my aquarium, it's around 800ml per day.

- My pH varies from 7.4 to 8.0 (8.0 last 2-3h)

- I don't see any benefit of using vinegar since I will drop the pH

- My apartment is a corridor of air during summer, the Co2 is around 600ppm and less (500 while writing)

- I tested air bubble pump just for fun and yep, doesn't affect pH (as expected...)

- I added directly powder to the aquarium, boy that kalkwasser doesn't mix well in water, it's terrible. But I did notice a slight increase of pH, however, I added such a small amount that it didn't affect much the tank. I'm concern with what's left of the residue... and perhaps the impurity.

- all my tank have similar pH. (nano) 2 of them doesn't have skimmer, and yet same pH.


I just can't get that pH raise. I'm hitting a wall around 7.9, there seems to be an equilibrium with the air and the water and Co2 that I can't disturb (for now).

I'm considering to buy another source of Calcium hydroxide but I doubt it will make any difference. The biggest issue with Kalkwasser is how bad it mix with water (concentration).

It kind of ticks me off also because many reefers locally are telling me they reach 8.3 easily and I just don't know why I can't replicate the same.
 

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So to be clear, adding Kalkwasser to your tank has no pH benefits? Or the benefits are short lived?
 
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I see the rise of pH when added, but ... that pH doesn't last and it gets in equilibrium like my other tank that has 0 dosing (at the moment... while I do the test)
 

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I see the rise of pH when added, but ... that pH doesn't last and it gets in equilibrium like my other tank that has 0 dosing (at the moment... while I do the test)

Are you running a skimmer that is aerating your tank with the higher CO2 house air?
 

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Simply using the Tunze Skimmer 9004 with nothing else (No Co2 scrubber (that is my very last resort)

So your super effective aeration unit (skimmer) will effectively counteract your Kalkwasser pH boost.

 
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Alright so i've done other experiment.
About that Skimmer and air contact mixing, I think you are right @arking_mark , since I turn off the skimmer, the pH started to raise.

Now my issue still remain the same since the beginning: The concentration.
My only way to reach desirable level of pH/alk/cal is by dosing the sediment on the bottom of the bottle.

The saturated water is almost useless, and I'm starting to consider that powder is ... old, been in contact with air, not sure, but the potency seem bad. I've never been able to reach above 12.1 of pH in the saturated water, I don't know if it's usual for most people or it is an issue since we can reach higher pH on paper.

On a side note, gosh kalkwasser is messy/dirty, I need to clean my stuff with vinegar
 

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You're welcome to experiment with dosing Kalkwasser slurry or raw Kalkwasser. However, I would not recommend doing this. You are likely going to cause a significant amount of CaCO3 precipitation.

My understanding of pH is that this directly determined by dissolved CO2 and Alk. At a given CO2 level, you can increase Alk to drive up your pH. If your home is high in CO2, keeping your Alk above 11dkh could get you a pH closer to 8.2.

However, you tank CO2 level will change throughout the day/season depending on people/pets in your home, open windows, and tank inhabitants...which will still result in pH swings.

There are also high-pH two-part balanced additives that aren't limited to your evaporation rate that may help you achieve your goal.

My goal was to get stable pH. My current pH is between 8.28 and 8.32. Knowing my pH, I'm now focused on stabilizing my Alk. If I stabilize my Alk around 7.7dKH, I know that my dissolved CO2 is roughly what's in a natural reef. As I've decided to use AFR to supplement my Kalkwasser, I'm still figuring out how to dial that in.
 
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What means AFR?

I think I'm done with Kalkwasser, I don't see it work with all my setup aquarium, it's not worth the effort vs the reward.
(With my setup/space/time available)

I put some in my Auto top Off bucket, but I can't fully close the lid, and I saw a white film on the surface, I don't want to disturb it, I'm thinking it must protect against the gas exchange.

I like natural ways, algae scrubber... but it could also strip a lot of nutriments.
 

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What means AFR?

I think I'm done with Kalkwasser, I don't see it work with all my setup aquarium, it's not worth the effort vs the reward.
(With my setup/space/time available)

I put some in my Auto top Off bucket, but I can't fully close the lid, and I saw a white film on the surface, I don't want to disturb it, I'm thinking it must protect against the gas exchange.

I like natural ways, algae scrubber... but it could also strip a lot of nutriments.

AFR is Tropic Marin's All-for-Reef. It's an all-in-one dosing product based on Calcium Formate.

I'm not sure what you mean by "natural ways" as I'm not aware of anything that adds major/minor elements/ions naturally.

My preference is ultra-low maintenance (ULM) and prefer simplified and automated techniques.

My understanding is you were looking to use Kalkwasser to provide balanced Ca/Alk dosing with its added pH boost. A 3ml/min drip for my 400L tank worked very well. The slow drip was much better at providing and maintaining a stable boost. However, I was still seeing pH swings and I reached my dosing limit with Kalkwasser. So I took it further by adding a Skimmer with recirculating CO2 scrubber.

You do not need to do this to have a successful tank.

Many reefers have incredible tanks with lower pH. The key is stability. If simpler to you is less equipment, maybe a high-pH two-part would be better. It wouldn't gunk up your ATO. It's not limited to your evaporation rate. It would still provide a nice pH bump.

To minimize pH swings, you can run a refugium or ATS on reverse lighting schedule. You can also dose the two-part heavier at night.
 

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