Kalkwasser as the main source of macro? Is anybody using it?

[thejacgues]

Hey there,

Following @Randy Holmes-Farley advice and BRS videos, I am keen on trying Kalkwasser as the key source of Ca, Alkalinity and pH increase.
The primary reason is the fact that it is supposedly straightforward followed by lack of additional NaCl accumulation which would require Component C addition.

What I would like to know is:
1. How close is the Calcium hydroxide's ratio of Calcium and Alkalinity to coral's growth demand? Is it even possible to dose only Kalkwasser without any other Ca / Alkalinity supplementation? I understand that too high pH is the main concern here, but it can be dropped with the use of vinegar (increase the solubility of CaOH solution, too).

2. How good are Kalkwasser Reactors? How much maintenance do they need and how reliable do they appear to be? I would like to run a huge 1000l tank (250gallon) on Kalkwasser, so the reactor seems to be the only way due to the poor solubility of CaOH.

3. Are there any other cons of this method that I am missing? Aside of pH and solubility, is there anything that would make it impossible to be used as the only source of macro (excluding Mg)?

 

[Randy Holmes-Farley]

Long term, kalkwasser adds a little bit more calcium than alk compared to coral consumption. It exactly matches pure calcium carbonate, but some magnesium gets into deposited CaCO3 in place of some calcium, leaving a little excess calcium in the water. Water changes generally keep this under control.

I’m not a fan of reactors, but they can work. I prefer dosing from a settled reservoir, which in my case was 3 x 44 gallon Brute cabs plumbed together.

I used kalkwasser and water changes as the only calcium and alk sources for 20 years. It’s a good method!

 

[benmed]

I use Kalk only at this point just for simplicity and set it and forget it mentality. I have the Kalkwasser in a brute which is dosed via the BRS 50 mL pump set to run once an hour for 12 hours overnight. There is an online calculator that will tell you how much to add and there is a program code generator for your apex if you need it. I’ve only been running the set up like this for about a month but it’s been really pretty easy so far. I just weigh the Kalkwasser, fill up the brute to the same marked level each time Let it go! Cal/alk for dodos

 

[thejacgues]

I’m not a fan of reactors, but they can work. I prefer dosing from a settled reservoir, which in my case was 3 x 44 gallon Brute cabs plumbed together.

Why aren't you a proponent of reactors? What are the cons? My space is limited, 3x 44 gallons containers is like a luxury. Space-wise, I can afford to fit maybe 12-13 gallons in total for Kalkwasser.

I use Kalk only at this point just for simplicity and set it and forget it mentality. I have the Kalkwasser in a brute which is dosed via the BRS 50 mL pump set to run once an hour for 12 hours overnight.

How much Kalkwasser does your aquarium consume and how big / dense inside is it?
Don't you have pH swings with such schedule? I understand the reversed cycle, but if that's the only source of Ca, I thought night time pH would be much bigger than the daytime + alkalinity swings.

 

[Randy Holmes-Farley]

Why aren't you a proponent of reactors? What are the cons? My space is limited, 3x 44 gallons containers is like a luxury. Space-wise, I can afford to fit maybe 12-13 gallons in total for Kalkwasser.

The drawbacks are that is is hard to get the water saturated ( biggest drawback, IMO), it can be hard to control potency, and settling of impurities is harder to control.

 

[benmed]

Why aren't you a proponent of reactors? What are the cons? My space is limited, 3x 44 gallons containers is like a luxury. Space-wise, I can afford to fit maybe 12-13 gallons in total for Kalkwasser.



How much Kalkwasser does your aquarium consume and how big / dense inside is it?
Don't you have pH swings with such schedule? I understand the reversed cycle, but if that's the only source of Ca, I thought night time pH would be much bigger than the daytime + alkalinity swings.

If your space is limited, a reactor may be your friend. The brute trash can is just cheap, easy and effective but I have the space for it.

I have a 120 gallon system and I put about a half gallon a night into it. Probably I get about 3 gallons of evaporation a day with a lot of surface agitation on my water surface from power heads. I also run my fuge at night. To be honest, all I can tell you is that the pH seems to stay pretty stable from day to night. Maybe that will change as the bio burden changes? But the apex keeps a pretty good eye on it (if you trust that probe). It holds around 8.1

 

[thejacgues]

The drawbacks are that is is hard to get the water saturated ( biggest drawback, IMO), it can be hard to control potency, and settling of impurities is harder to control.

I am planning to buy pharma grade 96% purity CaOH2. Quite pricey (20USD for 1lb) but that's the best that I found in my country. I hope that will decrease the risk associated with impurities.
I actually though about using not the saturated water, but water with some undissolved particles, that would go to sump and have plenty of space and water circulation there to get mixed before they reach the display tank. Does it make any sense or would it be impossible to to have quite consistent amount of Kalkwasser dosage?

If your space is limited, a reactor may be your friend. The brute trash can is just cheap, easy and effective but I have the space for it.

Maybe that will change as the bio burden changes? But the apex keeps a pretty good eye on it (if you trust that probe). It holds around 8.1

My space is limited, as well as weight / pressure I want to put on my floor. I live in apartment and I am planning to create a big peninsula tank on the middle of my living room. I would love to have a huge basement for the all backstage stuff, but it's impossible.

 

[Randy Holmes-Farley]

Some folks dose a slurry and find it works. I’d caution that standardizing how many suspended particles get dosed each day may be hard to control.

 

[14 foot reef]

I recently switched to only Kalkwasser for my Calcium & Alkalinity. My system is 850 gallons and I use a K2 Avest Marine stirrer with a Apex DOS pushing water through the reactor from RODI bin. I'm doing a reverse lighting schedule and have basically raised my PH from 7.7 night to 7.95 day to a basically flat line ph day and night at about 8.26.
CA over 24 hours goes from 425 down too 405 then back to 425 and ALK goes from 9.47 to 9.37 then back to 9.47

See apex 24 hour graph.

 

[Sisterlimonpot]

I also use a kalkwasser with a kalk reactor solely for a 300g sps dominant tank.

I designed a kalk controller that monitors tank pH and kalk pH and based on those parameters it sets various effluent rates throughout the day.

It seems to have solved the issue Randy points out with inconsistent saturation levels. If you want to check it out, here's the link for it

 

[bobnicaragua]

All I use on my 135 gal is saturated kalk, constantly dosed by a versa. I have mostly acros, so the kalk is enough at this point. In previous tanks, I had lots of plating and encrusting montipora and had to dose both kalk and 2 part.

 

[Crustaceon]

The thing that almost never gets mentioned when it comes to kalkwasser is that it's really dependent on ambient humidity. I tried running kalkwasser many times here in San Diego, but our humidity is too high here (60-80%) to be able to add enough saturated kalk to keep up with demand via ATO to match up with the equivalent on 50ml of soda ash solution per day IME. I can see it working if I ran central air all day long or a dedicated dehumidifier, but that's not happening here due to $$$. Even pointing fans at the water's surface was insufficient.

 

[thejacgues]

@Sisterlimonpot & @bobnicaragua How much lime water (saturated liquid) or calcium hydroxide (powder) do you use in your systems? I would like to calculate what my tank might need to know how big my kalkwasser container needs to be. I might end up having kalkwasaser in ATO + automatic measurement of kH & Ca, which would control pomps and supplement it with 3 parts balling. Not a perfect solution, but All I could fit is a 80l bucket (~ 30g) but I would like it to be able to supply a big, high demand tank for at least 2 weeks, which I am afraid is rather unlikely.

I can dissolve 16g in 1000ml of 20C water, which means I should be able to dissolve up to 108g of calcium hydroxide in the full barell. I am afraid 108g of powder wouldn't last for more than a week of quickly growing SPS in 800-1000l aquarium.

 

[Sisterlimonpot]

@Sisterlimonpot & @bobnicaragua How much lime water (saturated liquid) or calcium hydroxide (powder) do you use in your systems?

I can only give you estimates as to how much calcium hydroxide I use in a week. And that's partly due to the fact that I'm using a kalk reactor that I can simply pour powder in. I base refill on the pH inside the reactor, when it drops to 12.35 I get an alert and I go in and add roughly a cup every week. I haven't been keeping track of this because I heavily rely on the alert and once I refill the reactor I don't think about it until it alerts me again.

However, I can tell you that I am dosing 30L of saturated kalkwasser into my tank daily. And to get a sense of my coral demand, I recently updated my build thread with a video of my tank. You can check that out by clicking on my "Build Thread Contributor" badge below my avatar.

 

[Randy Holmes-Farley]

If you know your tank volume and the alk decline per day, it is easy to use a calculator to determine the volume needed each day. Often is is something like 1-2% of the tank volume.

 

[thejacgues]

If you know your tank volume and the alk decline per day, it is easy to use a calculator to determine the volume needed each day. Often is is something like 1-2% of the tank volume.

The whole thing is... I don't know it yet. I any in the process of preparations to build my dream tank. Even though energy prices increased 5-fold here within last months and it will be super expensive, I am determined to do it anyway. I would have gone with Calcium Reactor, but pH is an issue and getting it on levels higher than 8.1 will make it complex and expensive. I would love to go with sodium hydroxide or soda ash 2-part, but without water changes the component C is vital and that would again increase the long-term maintenance prices.

That's why I am trying to figure it out if with my limited space under the tank I will be able to acheive a reasonable conditions to go for Kalkwasser.

Another idea I have is: putting a 80l barell for ATO, which will consist of Kalkwasser solution.
The container will fill up with water directly from RODI system only once nearly empty.
I am trying to figure out a way of automatic addition of CaOH2 powder inside (similar way as automatic feeders do), which then will be shortly mixed with the water.

Barell's almost empty -> RODI supplys it with water up to certain level -> Circulatory pump inside kicks in -> Device adds certain portion of CaOH2 powder -> solution gets mixed for 1 minute -> pump turns off and saturated water is ready to be used in ATO.
I want would love to automate it, so neither solubility of CaOH2 is not a limiting factor, nor the barell's size. The aim is to let the system rely on itself, without manual intervention for weeks in the given setup.

What do you guys think? Is that crazy?

 

[benmed]

Kalkwasser will beat up the pumps

 

[Randy Holmes-Farley]

The whole thing is... I don't know it yet. I any in the process of preparations to build my dream tank. Even though energy prices increased 5-fold here within last months and it will be super expensive, I am determined to do it anyway. I would have gone with Calcium Reactor, but pH is an issue and getting it on levels higher than 8.1 will make it complex and expensive. I would love to go with sodium hydroxide or soda ash 2-part, but without water changes the component C is vital and that would again increase the long-term maintenance prices.

That's why I am trying to figure it out if with my limited space under the tank I will be able to acheive a reasonable conditions to go for Kalkwasser.

Another idea I have is: putting a 80l barell for ATO, which will consist of Kalkwasser solution.
The container will fill up with water directly from RODI system only once nearly empty.
I am trying to figure out a way of automatic addition of CaOH2 powder inside (similar way as automatic feeders do), which then will be shortly mixed with the water.

Barell's almost empty -> RODI supplys it with water up to certain level -> Circulatory pump inside kicks in -> Device adds certain portion of CaOH2 powder -> solution gets mixed for 1 minute -> pump turns off and saturated water is ready to be used in ATO.
I want would love to automate it, so neither solubility of CaOH2 is not a limiting factor, nor the barell's size. The aim is to let the system rely on itself, without manual intervention for weeks in the given setup.

What do you guys think? Is that crazy?

I personally would not dose a slurry at any demand level. I'd use a two part on top of kalkwasser if normal kalkwasser was inadequate. IMO, it will be difficult to standardize slurry dosing. What you are trying may work, but seems prone to issues to me.

I'd also try normal saturated kalkwasser and see if that works out before going to a more complicated means.

 

[atoll]

Kalkwasser will beat up the pumps

I use a stirer fed via my ATU at night no need for kalk to pass through a pump.

 

[thejacgues]

I personally would not dose a slurry at any demand level. I'd use a two part on top of kalkwasser if normal kalkwasser was inadequate. IMO, it will be difficult to standardize slurry dosing. What you are trying may work, but seems prone to issues to me.

Thanks Randy. I need to admit - I was surprised when I realize how tall stirrer works. It simply cannot supply tank with equal amounts of limewater, the logic is broken at its foundations.

I think I will go with your recommendation and here's my idea on what to do:
I will use kalk stirrer / ATO with kalk and rely on my auto measurement of kH to supplement it with a 3-part to the level, that would ensure my kH is stable. Using sodium carbonate as the only kH additive in 3-part should also help stabilize pH a little bit. I do not plan to make any water changes, that's why I think 3-part would be more suitable. I will also experiment with ozone applied to a skimmer and supplement it with activated carbon to get rid of potential DOC accumulation.

What do you think?