How much does air affect Kalkwasser potency?

[trevorhiller]

How much does air effect Kalkwasser potency? I’ve heard about ACI’s method of floating a piece of styrofoam on the water surface to prevent air-kalk interaction. My question is do you do this? Is it helpful for maintaining Kalkwasser potency?


I’ve got a 10 gallon brute bin behind my tank with Kalkwasser that goes in via a dosing pump. I put a piece of styrofoam on the surface figuring it can’t hurt, maybe it helps keep the Kalkwasser pH up. But the styrofoam often gets hung up on my float switch and dosing line.

I was thinking about alternative DIY floating lids and remembered a video I saw on YouTube. They use a “shade balls” on water reservoirs in the southwest to prevent water evaporation. This gave me the idea of making a floating Kalkwasser lid with ping pong balls. It seems like it would work fantastic, but I’m not sure if it’s even necessary. Perhaps a solution to a problem that doesn’t exist.

I’m curious if anyone is using a similar floating lid and has measured a difference in Kalkwasser pH with and without it.

Here’s a video of the concept I’m referring to:

 

[DanyL]

That's an interesting concept, following along.

 

[Randy Holmes-Farley]

A simple lid on limewater (kalkwasser) in an unstirred Brute can prevents degradation to a sufficient degree. Don't stir it or leave it open to the air.

I show data backing up these assertions here:

The Degradation of Limewater in Air - Reefkeeping.com

for example:


Figure 2. The conductivity of the limewater in my dosing reservoir as a function of time.

 

[atoll]

Kalk should form a kind of skin/scum on the surface which is supposed to stop or at least greatly reduce interaction with air. How affective this is I don't know perhaps Randy knows. Most if not all kalk stirrers are not airtight inc the Aqua Medic I have and the Deltec ones.

 

[Randy Holmes-Farley]

Kalk should form a kind of skin/scum on the surface which is supposed to stop or at least greatly reduce interaction with air. How affective this is I don't know perhaps Randy knows. Most if not all kalk stirrers are not airtight inc the Aqua Medic I have and the Deltec ones.

It does help, yes. Here's a picture of a partial coating:

http://reefkeeping.com/issues/2005-07/rhf/index.htm

Figure 5. A view of my limewater reservoir showing a thin calcium carbonate crust on part of the liquid surface, and heavy deposits of calcium carbonate, calcium hydroxide, magnesium hydroxide, and other materials on the bottom. I clean out the bottom of the reservoir only once a year or so.

Precipitates on Top of Limewater
The precipitate that forms on the top of limewater is calcium carbonate (Figure 5). Limewater is high in calcium (about 800 ppm at saturation) and is very high in pH (pH 12.54 at saturation), meaning that it contains a lot of hydroxyl ions (OH-). When carbon dioxide from the air encounters the water, it hydrates to form carbonic acid:

(1) CO2 + H2O → H2CO3

Then, if the pH is above 11, as it is in limewater, the carbonic acid equilibrates to form mostly carbonate:

(2) H2CO3 + 2OH- → 2H2O + CO3--

It is the carbonate that we are concerned with in the formation of insoluble calcium carbonate, both on the surface of, and inside, the limewater:

(3) Ca++ + CO3-- → CaCO3 (solid)

The result of this reaction is visually obvious. The calcium carbonate can be seen as a solid crust on the limewater's surface that has been exposed to the air for a day or two (do not bother to remove this crust; it may actually be protecting the underlying limewater from further penetration by carbon dioxide). The formed solids also settle to the bottom of the container, and can, in fact, form down inside it. Since solid calcium carbonate is not an especially useful calcium or alkalinity supplement, this reaction has the effect of reducing the limewater's potency. With sufficient exposure to air, such as by aeration or vigorous agitation, this reaction can be driven to near completion, with little calcium or hydroxide remaining in solution.

 

[atoll]

My crust is unbroken in my stirrer, not sure how much you're broken crust is effective.

 

[DeputyDog95]

A simple lid on limewater (kalkwasser) in an unstirred Brute can prevents degradation to a sufficient degree. Don't stir it or leave it open to the air.

I show data backing up these assertions here:

The Degradation of Limewater in Air - Reefkeeping.com

for example:


Figure 2. The conductivity of the limewater in my dosing reservoir as a function of time.

Interesting info, Randy!

I read your Kalk article yesterday.

A couple of questions for you...

Do you think there is much value in a Kalk Stirrer/Reactor?

It would seem like, based on your article, that even an uncovered Kalk container still stayed pretty potent, right?

I am playing around with just dosing it out of a 5 gallon bucket right now. It got a thick crusty skin on it, which led me to this thread when I was googling the topic.


Can I get just as effective results out of a bucket as a stirrer/reactor?

Also, do you think some Kalk brands are better than others?

For my temporary experiment right now, I'm using an empty dosing head on my red sea doser, a 5 gallon plastic red sea salt bucket, and some ME Corals Kalk I got at my local LFS, but it looks like it has probably been on the shelf for a decade lol

I am only dosing 1000ml/day (max capacity of the current doser) in a system with a net water volume of likely 120g (DT and Sump), and haven't really noticed any difference at all in pH or a need for reducing my Alk/Ca additives.

Lastly, how are you measuring the conductivity of the solution?
I have a Hanna salinity conductivity meter, but I'm assuming that would not be helpful for something like this.

 

[Randy Holmes-Farley]

IMO, dosing limewater from a settled reservoir is a better plan unless space is the limiting factor. It is easier to control potency, and some impurities can settle out.

I drew it from a 130 gallon reservoir made from 3 brute cans.

 

[DeputyDog95]

IMO, dosing limewater from a settled reservoir is a better plan unless space is the limiting factor. It is easier to control potency, and some impurities can settle out.

I drew it from a 130 gallon reservoir made from 3 brute cans.

Wow, how long did that last you???

 

[Randy Holmes-Farley]

Wow, how long did that last you???

Typically about a month.

 

[DeputyDog95]

Typically about a month.

Wow, that is about 4 gallons a day. Must be a big system!

 

[Miami Reef]

Wow, that is about 4 gallons a day. Must be a big system!

If I remember correctly, his tank was about 120 gallons, but he had brutes of rock filled refugia that increased his volume to around 300gal.

 

[Randy Holmes-Farley]

If I remember correctly, his tank was about 120 gallons, but he had brutes of rock filled refugia that increased his volume to around 300gal.

Yes. Sometimes it lasted longer (maybe up to 2 months) depending on the season.

The refugia and sumps (typically 5 x 44 gallon Brute cans ) were mostly covered and a bathroom fan sucked air out from each of them and exhausted it outside, causing plenty of evaporation, especially in winter.

 

[DeputyDog95]

Maybe you guys could give me some input.

So I'm using fully saturated Kalk (ME Corals/2 teaspoons per gallon in a 5g container) and dosing 1000ml per night over a 12-hour period. I'm limited as to how much I can dose right now because of the doser I'm using. It's a red sea, I had an empty head so I thought I would experiment a little to see what kind of affect Kalk has on my system. But the doser does cap out at 1000ml/day per can you can't dose more than 24 times in a one day period (basically once per hour). So I'm doing it once per hour, overnight for a total of 12 doses from 6p to 6a.

I'm also currently dosing around 150ml/day of Red Sea liquid alkalinity. The system has a net volume (sump and DT) of around 120g and is heavily populated with SPS and a large clam.

However, I have not seen really any increase in pH or reducing my need to dose Alk or Ca.

Am I doing something wrong here? Or is a 1000ml dose just too small to really have an affect on my particular system?

 

[Randy Holmes-Farley]

Maybe you guys could give me some input.

So I'm using fully saturated Kalk (ME Corals/2 teaspoons per gallon in a 5g container) and dosing 1000ml per night over a 12-hour period. I'm limited as to how much I can dose right now because of the doser I'm using. It's a red sea, I had an empty head so I thought I would experiment a little to see what kind of affect Kalk has on my system. But the doser does cap out at 1000ml/day per can you can't dose more than 24 times in a one day period (basically once per hour). So I'm doing it once per hour, overnight for a total of 12 doses from 6p to 6a.

I'm also currently dosing around 150ml/day of Red Sea liquid alkalinity. The system has a net volume (sump and DT) of around 120g and is heavily populated with SPS and a large clam.

However, I have not seen really any increase in pH or reducing my need to dose Alk or Ca.

Am I doing something wrong here? Or is a 1000ml dose just too small to really have an affect on my particular system?

What size aquarium are you adding it to? it's certainly adding far, far less than the red Sea additive.

Red Sea Foundation B liquid is 88 times more potent than saturated kalkwasser, so to match the alk addition effect of 150 ml of Red Sea Foundation B, you'd need to be adding 13.3 liters per day of kalkwasser.

If you want to use hydroxide, maybe a DIY two part using sodium hydroxide would be more suitable since it much more potent than kalkwasser.

 

[Potatohead]

Maybe you guys could give me some input.

So I'm using fully saturated Kalk (ME Corals/2 teaspoons per gallon in a 5g container) and dosing 1000ml per night over a 12-hour period. I'm limited as to how much I can dose right now because of the doser I'm using. It's a red sea, I had an empty head so I thought I would experiment a little to see what kind of affect Kalk has on my system. But the doser does cap out at 1000ml/day per can you can't dose more than 24 times in a one day period (basically once per hour). So I'm doing it once per hour, overnight for a total of 12 doses from 6p to 6a.

I'm also currently dosing around 150ml/day of Red Sea liquid alkalinity. The system has a net volume (sump and DT) of around 120g and is heavily populated with SPS and a large clam.

However, I have not seen really any increase in pH or reducing my need to dose Alk or Ca.

Am I doing something wrong here? Or is a 1000ml dose just too small to really have an affect on my particular system?

I suspect it's not enough. My system is about 70 gallons and I dose about 1800 ml per day (24 hours) which is the max I can due to evap. So I dose about double what you do into almost half as much water and my pH only goes up about .15 due to kalk.

 

[DeputyDog95]

What size aquarium are you adding it to? it's certainly adding far, far less than the red Sea additive.

Red Sea Foundation B liquid is 88 times more potent than saturated kalkwasser, so to match the alk addition effect of 150 ml of Red Sea Foundation B, you'd need to be adding 13.3 liters per day of kalkwasser.

If you want to use hydroxide, maybe a DIY two part using sodium hydroxide would be more suitable since it much more potent than kalkwasser.

The system has a net volume of approximately 120g between the DT and the sump.

13 liters is about 3.5 gallons. I don't think I evaporate anywhere near the volume.

I have an ET Versa pump coming next week, which is much more appropriate for this application. I'm not looking to replace the Red Sea liquid dosing supplements, I just want to use less of it and get a pH bump during the overnight hours to raise my lowest pH point.

Right now, at 1000ml, I'm dosing the equivalent of about a quarter of a gallon. I guess I'll try and step it up to a gallon when the pump comes in and see where I land with that.

Thanks!

 

[Randy Holmes-Farley]

. I'm not looking to replace the Red Sea liquid dosing supplements, I just want to use less of it and get a pH bump during the overnight hours to raise my lowest pH point.

Which is exactly what a DIY two part will do, replacing some or all of the red Sea additive.

1 L of kalkwasser in 120 gallons in mostly meaningless. Adding that whole volume at once without a pump would boost pH less than 0.1 pH unit, alk by 0.25 dKH, and calcium by about 2 ppm.

 

[DeputyDog95]

Which is exactly what a DIY two part will do, replacing some or all of the red Sea additive.

1 L of kalkwasser in 120 gallons in mostly meaningless. Adding that whole volume at once without a pump would boost pH less than 0.1 pH unit, alk by 0.25 dKH, and calcium by about 2 ppm.

Agreed! I'm experiencing no appreciable benefit at this volume. But when the Versa pump shows up, I can always try upping the the nightly dose to 4000ml over the 12 hour period.

I'm pretty happy w the Red Sea products though. And I'm kind of lazy, so just swapping the entire dosing bottles is pretty easy when they're empty. Plus I use their trace elements as well.

The "Kalk juice" may not be worth the squeeze at this tank volume/consumption. I'm not looking to be mixing 55 gallon drums full of Kalk

I'm only trying to do this at night to bring my "low pH" point up to 8.3 so my daily range is 8.3 to 8.5.

If you had to make a rough guess, how much Kalk do you think it would take to boost the pH from 8.2 to 8.3, over the course of night in my system? My current pH range is 8.2 to 8.5, but I would like to tighten that up a little bit since I've seen such a tremendous boost from running my C02 scrubber. I used to be at 7.9 to around 8.1, night and day difference with the pH being higher. The growth has been explosive and my Alk consumption has tripled over 2 months.

 

[DeputyDog95]

Just to follow up...

I bought an ET Versa pump it and put it online to dose the Kalk instead of the Red Sea pump.

This pump is perfect for Kalk. It's continuous, let's you put whatever volume you want to do dose in the system and automatically calcs the ml/hour dosing rate, and you can put whatever you want for the container volume. The red sea was significantly more limited, but in their defense, it wasn't designed for this type of duty.

So, I was dosing 1L over the course of 12 hours at night with the RS doser and it had zero impact on the pH or Alk/Ca.

I set the Versa to dose 3L during the same period. I think it was 7p to 7a. Basically sunset and sunrise in my system.

Big difference. It bumped the floor of the pH up by around .13 and even reduced the need to add some Alk/Ca during that period.

Very pleased w my little experiment so far. I'm dosing out of 5 gallons RS salt buckets with a double ended john guest fitting in the lid with gaskets, so the container is sealed tight. Seems to be keeping the mixture isolated from the air, as when I just had the lid sitting on top of the bucket, the Kalk would form a thick crusty film on the top. I've spot checked this setup a few times and nothing on top now. Just clearish liquid with the powder on the bottom.

I'm officially intrigued and would like to explore the option of using a much larger container. Right now, I can only put about 4.5 gallons in the container and that will get me about 5 days. Too much maintenance. And if I wanted to actually use more Kalk to reduce my RS liquid CA and Alk usage, it's going to need to be a way bigger container. But then you have to balance how long it will last based on volume and how long it will last based on potency.

So still figuring things about.

But back on this topic....

Do you think a 55-g container that could be sealed would be too large a vat of Kalk to retain it's potency over say, a month?