Using water from your tank for kalkwasser

[Aqua Splendor]

Sorry if it's dumb but I love testing different things even if it doesn't make sense.
I was trying to replace again my other dosing method by using Calcium hydroxide.

Lately, I've been using the water from my tank instead of RODI freshwater, I did notice some effects, some positive, some neutral, and I fear one negative in long term.
But before I have one question:

Why not use water tank instead of RODI freshwater?
Precipitation?
Thank you

 

[blaxsun]

A couple reasons off the top of my head. One, to prevent the intake line from getting clogged with anything from the tank. Two, to prevent bacteria, etc. from entering the reactor and potentially evolving into a new life form.

 

[Reffetsevla]

Sorry if it's dumb but I love testing different things even if it doesn't make sense.
I was trying to replace again my other dosing method by using Calcium hydroxide.

Lately, I've been using the water from my tank instead of RODI freshwater, I did notice some effects, some positive, some neutral, and I fear one negative in long term.
But before I have one question:

Why not use water tank instead of RODI freshwater?
Precipitation?
Thank you

If you are using it to top off the tank, your salinity will rise with tank water. RO/DI will not raise that.

Same with dosing manually, just smaller amounts I would think.

 

[Aqua Splendor]

If you are using it to top off the tank, your salinity will rise with tank water. RO/DI will not raise that.

Same with dosing manually, just smaller amounts I would think.

Just to be clear I'm referring about using the water from your tank, basically, you just mix the calcium hydroxide inside a container where the pH is higher.

 

[Randy Holmes-Farley Verified Community Expert]

Just to be clear I'm referring about using the water from your tank, basically, you just mix the calcium hydroxide inside a container where the pH is higher.

It cannot be done without massive precipitation of magnesium hydroxide and calcium carbonate.

 

[Randy Holmes-Farley Verified Community Expert]

What's the long term negative?

Only one I know of is that it delivers a slight excess of calcium relative to alk, so calcium rises (when maintaining alk) and using a lower calcium mix for water changes solves it.

I used it for 20 years as the only alk and calcium addition on my tank.

 

[Aqua Splendor]

It cannot be done without massive precipitation of magnesium hydroxide and calcium carbonate.

Sorry, I don't follow the magnesium hydroxide, I do not dose this. only Calcium Hydroxide.

As for the magnesium level, it doesn't change in my aquarium. (testing with salifert)

Calcium carbonate on the other hand yeah, that's is my issue I think I've noticed. However, I do not want to screw up with the term (my brain mix with other stuff). Basically, the drawback is the precipitation of all sorts but mostly calcium carbonate inside the bottle. It's what I believe is happening, but unsure.

Here is what I've noticed:
- pH goes up
- Alkalinity goes up
- Calcium is canceled.

The last few times I was playing with Calcium hydroxide I had issues with calcium accumulation, but this time it is the opposite. I need to add calcium.

Now I've noticed the sand, the rock, have some sort of build-up of... film, "hard dust". Nothing alarming, but I do fear over a long period of time, I mean I can just use a turkey blaster and it gets filtered later...

Also right now my bottle is a bit in "bad shape" (playing with different things) and I've noticed my pH inside the bottle was around 12.


The reason why I started to use the water from my tank instead of RODI water, is because I needed to add more kalkwasser solution in the tank but the evaporation wasn't enough. Evaporation becomes a bottleneck.

I'm also doubly compensating by what is added in the tank, it sucks up a more slurry concentration however I do not like this since I've had an issue maintaining a steady level of concentration. (Next time I will come back to sucking up the clear water part, more reliable)

Another thing I've noticed, I'm unable to maintain a steady pH level during the night, every time the buffer capacity equilibrium gets the upper hand: falls at 8.0, spike at 8.0, goes back to 8.0 before the next dosage.

 

[HuduVudu]

@Aqua Splendor you can do it but you have to be careful that you don't let the solution get higher than 8.6 or what Randy said will be true.

An ugly thread that explains what I did:

Soda poppin' ... and how to dose infinite Kalk

Ok, how I arrived at this crazy simple stupid idea was kinda like this: It started a long time ago when wet dry filters were still dominant and only the cool kids built Berlins. I had gotten back into the hobby after being in the Philippines and I was absolutetly enamored with live coral, I...

www.reef2reef.com

 

[Aqua Splendor]

Gnn whats wrong with this forum can't edit posts, to clarify the pH at night, I meant pH 8.0 to 8.1 than 8.0

 

[Randy Holmes-Farley Verified Community Expert]

Sorry, I don't follow the magnesium hydroxide, I do not dose this. only Calcium Hydroxide.

As for the magnesium level, it doesn't change in my aquarium. (testing with salifert)

Magnesium hydroxide is the immediate precipitate that forms when adding any high pH additive (such as kalkwasser) to to seawater. Hydroxide from the kalkwasser and magnesium from the seawater.

When it is diluted and mixes in, it can redissolve which is why isn't not a huge problem for folks dosing hydroxide or carbonate for alk, even though a precipitate is visible.

 

[Randy Holmes-Farley Verified Community Expert]

The reason why I started to use the water from my tank instead of RODI water, is because I needed to add more kalkwasser solution in the tank but the evaporation wasn't enough. Evaporation becomes a bottleneck.

That's a problem that can partly be reduced by dosing a slurry or by adding vinegar to the kalkwasser, but it is the primary reason that more tanks do not use kalkwasser for all calcium and alk.

 

[Aqua Splendor]

Magnesium hydroxide is the immediate precipitate that forms when adding any high pH additive (such as kalkwasser) to to seawater. Hydroxide from the kalkwasser and magnesium from the seawater.

When it is diluted and mixes in, it can redissolve which is why isn't not a huge problem for folks dosing hydroxide or carbonate for alk, even though a precipitate is visible.

Wait so Magnesium Hydroxide that precipitated in the bottle gets redissolved when it goes back to the tank? Kinda cancel each other in a way? If so, why worry about magnesium level, if I understand this correctly? (Which like I observed doesn't seem to be affected)

What about calcium precipitation? Should I worry in any way in the long term?

Is there a reason why I shouldn't do this overall? Because so far so good. (?)

 

[homer1475]

Your misunderstanding randy.

Magnesium hydroxide will be precipitated out from the salt water if you mix Kalk with it(PH reaction).

If you mix kalk in RO/DI it is diluted enough to not cause that in the tank when added to SW.

 

[Randy Holmes-Farley Verified Community Expert]

Wait so Magnesium Hydroxide that precipitated in the bottle gets redissolved when it goes back to the tank? Kinda cancel each other in a way? If so, why worry about magnesium level, if I understand this correctly? (Which like I observed doesn't seem to be affected)

What about calcium precipitation? Should I worry in any way in the long term?

Is there a reason why I shouldn't do this overall? Because so far so good. (?)

What bottle?

Adding calcium hydroxide to seawater to make a dosing solution is a bad plan for the reasons I specified. Yes, the magnesium hydroxide will likely redissolve if you added a slurry of that mud back to the tank, but calcium and magnesium carbonate cannot redissolve in normal seawater.

People have been using kalkwasser for decades, and it is done the way it is done because that works best.

 

[Aqua Splendor]

The bottle:

Alright so, to understand: (Quote me and say correct/incorrect and detail where it's needed)
The calcium hydroxide turns into Calcium Carbonate, which cannot be used by coral, which I'm assuming is not detected by salifert test kit.

Now when you say you are worried about the excess calcium you meant Calcium Carbonate right?

So basically All the calcium from kalkwasser is kinda wasted because seawater is already saturated.

This is what I observed.

However, for the magnesium part, I do not see any difference because the magnesium redissolves anyway, correct?

So the only thing that is bad about that method is the calcium carbonate formation that is not being taken by coral?

Now my question is, what are the effects of calcium carbonate over the years if, for example, no water change is made?

 

[Randy Holmes-Farley Verified Community Expert]

Calcium carbonate is sand and rock.

The main "bad" thing is the kalkwasser is converted into useless sand. That doesn't seem bad enough?

The next bad thing is depletion of magnesium, not all of which will ever redissolve even if you add the mud to the tank because some is precipitated as calcium/magnesium carbonate.

Seriously, this is a dead end. Folks (including expert chemists) have pondered how to improve kalkwasser delivery. This is not one of the ways that works.

 

[Aqua Splendor]

Very interesting, this is actually good news!

For aquariums that don't need magnesium dosage and have very low calcium demand, this is a very great way to control the pH and Alkalinity.

Why do you say "useless sand. that doesn't seem bad enough?"
Why this comment?

So the counterpart is just a bit more cloudy water/dust. (?), which a good mechanical filter (Floss/roller) could remove some of it. (?)

I'm not looking for the optimal way, I'm just looking to understand the side effect.

 

[Randy Holmes-Farley Verified Community Expert]

Very interesting, this is actually good news!

For aquariums that don't need magnesium dosage and have very low calcium demand, this is a very great way to control the pH and Alkalinity.

Why do you say "useless sand. that doesn't seem bad enough?"
Why this comment?

So the counterpart is just a bit more cloudy water/dust. (?), which a good mechanical filter (Floss/roller) could remove some of it. (?)

I'm not looking for the optimal way, I'm just looking to understand the side effect.

Why this comment?
I'm at a loss for words why anyone would want to do this despite the problems.

Trying again..
Because this method accomplishes nothing except messing up the ionic balance of the seawater you used.

The method will:

1. Reduce magnesium. Not just not add any, kalkwasser alone doesn't add any, this method will actually reduce it in the tank by reducing soluble magnesium in the salt water you used.

2. Add less alkalinity than kalkwasser dissolved into fresh water would deliver because at the end of the day, you precipitated all of the carbonate alkalinity out of the seawater (as useless calcium carbonate), and are trying to dissolve kalkwasser into a mix that already has a bunch of calcium in it (which greatly reduces the calcium hydroxide that will dissolve).

3. Add less calcium than kalkwasser dissolved into fresh water would deliver because at the end of the day, you precipitated all of the carbonate alkalinity out of the seawater (as useless calcium carbonate). That drops calcium. Then you are trying to dissolve kalkwasser into a mix that already has a bunch of calcium in it (which greatly reduces the additional calcium hydroxide that will dissolve).

I see no reason to do it, and 3 great reasons to not do it.

Other trace elements will also likely precipitate. Some minor ions as well, such as strontium.

 

[Aqua Splendor]

interesting confirmation, I appreciate the answers. I think your frustration/desperation is coming from the assumption that all aquariums contain SPS/Hard coral. Not all aquariums are the same

So let's consider this scenario:

In a case, you have an aquarium that does not require Calcium or Magnesium supplements, you do a water change every month to re-establish different balances but you are looking for a way to raise back your alkalinity and you are also looking to raise the pH to benefit the whole system.

What other better lazy method could accomplish the same thing?
(Soda ash? hmm nan)

Everything I can think of have worst maintenance Cons or raise/reduce something that could be more dangerous than cal/mag.

I was actually considering using Kalk from Brightwell for that type of scenario, would be better than pure kalkwasser?

 

[Randy Holmes-Farley Verified Community Expert]

interesting confirmation, I appreciate the answers. I think your frustration/desperation is coming from the assumption that all aquariums contain SPS/Hard coral. Not all aquariums are the same

So let's consider this scenario:

In a case, you have an aquarium that does not require Calcium or Magnesium supplements, you do a water change every month to re-establish different balances but you are looking for a way to raise back your alkalinity and you are also looking to raise the pH to benefit the whole system.

What other better lazy method could accomplish the same thing?
(Soda ash? hmm nan)

Everything I can think of have worst maintenance Cons or raise/reduce something that could be more dangerous than cal/mag.

I was actually considering using Kalk from Brightwell for that type of scenario, would be better than pure kalkwasser?

If you want alk and pH and no calcium or magnesium, then dose sodium hydroxide.

All the benefits of pH boost and alkalinity without any complications about solubility limitations.


Don't get me started on Brightwell Kalk+2. It has less magnesium than ordinary bulk calcium oxide that I bought.