Can You Help Me Switch from Two-part to Kalkwasser?

[nickkohrn]

Looks right but how much do you evaporate a Day is the next question?

My system’s evaporation rate is roughly 0.75g each day.

I’ve never used that program, but your value seems a little low, but in the ballpark to me. I would start there and be sure to test alkalinity daily for a while.

I guess I better pick up a few reagents for my Hanna Checker then.

 

[dwest]

My system’s evaporation rate is roughly 0.75g each day.


I guess I better pick up a few reagents for my Hanna Checker then.

I think you will be successful with this.

 

[Ecvernon]

That looks like a good starting point. Testing will definitely be needed. As you start using kalkwasser theoretically the pH will get higher and growth will increase thus leading to more kalkwasser needed.

The limit to how much Kalkwasser solution you can add to your tank when your SPS colonies grow out would Be around 1.5 gallons a day as yous use around 3 gallons RODI top off in 2 days.

Edit: just noticed you evaporate less than that.
"I ask because the freshwater reservoir that is built into my sump holds about three gallons of water; I refill it every other day regardless of how much has been used (typically half or more)."

 

[nickkohrn]

As you start using kalkwasser theoretically the pH will get higher and growth will increase thus leading to more kalkwasser needed.

The typical pH range of my system is between 8.0 and 8.5, which is due to the usage of a carbon dioxide scrubber. I’d like to rely on kalkwasser, if possible, because I go through a 7.5lb. bag of media each month.

 

[Dkeller_nc]

I suspect this may have already occurred to you, but the best fix for low pH is to actually solve the fundamental issue, which is too high of a CO2 concentration in your room air, too little gas exchange between your tank water and the room air, or both.

Even if you continue to run your CO2 scrubber and/or use kalk, solving those root-cause problems will mean that you need to use far less CO2 scrubber media. Note that the pH boost of adding kalk to the tank is a temporary, non-equilibrium effect that will dissipate as gas exchange from the tank water to the room air "catches up". So to make the pH effect useful, you'll want a dosing pump that is capable of relatively slow speeds and is rated for continuous operation. The absolutely ideal theoretical method would be to calculate the tank's consumption, figure out how much kalk you need to meet that consumption (which you've already done), and then set the flow rate of the dosing pump so that the speed it runs at will yield the exact amount you require over the time period that you're dosing it.

Note that I mention "the time period that you're dosing it" instead of 24 hours. Depending on your particular tank's pH cycle behavior, you could choose to only spread the kalk dose over the nighttime hours and have it off during the day, or if the indoor CO2 concentration in your home is really high (>600 ppm), over a 24 hour period.

Another tip about kalk reactors - to be really useful, they require at least weekly maintenance. Specifically, as new RODI enters the unit, the dissolved CO2 that comes along with it will react with the kalk to form calcium carbonate, which is insoluble and becomes incorporated into the undissolved slurry at the bottom of the reactor. Not only that, individual particles of calcium hydroxide (kalk) can become coated with calcium carbonate as the surface of the particle reacts with the CO2 coming in with the RODI.

The bottom line is that the reactor needs to be emptied out completely, rinsed, and re-charged with kalk powder occasionally, and more kalk powder needs to be added on at least a weekly basis even if there's visible slurry on the bottom of the reactor, since a substantial amount of that visible slurry may be calcium carbonate or calcium carbonate-coated kalk powder.

 

[Randy Holmes-Farley Verified Community Expert]

Dont did it....

Unless you have a good amount of Alk (carbonate) consumption.... you'll slowly put your tank in the 13-16dKH range using Kalkwasser.

Dissolved Kalk is like 40-60dKH .... so unless your corals consume a lot of carbonate, you'll end up in dangerous dKH

Speaking from an unfortunate experience where I killed quite a bit SPS by my tank is a low carbonate consumption tank



.
.

Why do you assume he is going to overdose? He can dose as little as he wants using a timer.

 

[nickkohrn]

I suspect this may have already occurred to you, but the best fix for low pH is to actually solve the fundamental issue, which is too high of a CO2 concentration in your room air, too little gas exchange between your tank water and the room air, or both.

My wife and I live in Ohio, where it is uncomfortable to keep the windows open throughout the summers and winters. During days of comfortable temperatures, I open windows, and I do notice that the pH of my system increases to 8.0. It’s just the two of us and our dog, but it seems to be enough to cause the pH of my system to stay around 7.8 without intervention; I’m not able to run an airline from my skimmer to the outside of my apartment.

Even if you continue to run your CO2 scrubber and/or use kalk, solving those root-cause problems will mean that you need to use far less CO2 scrubber media. Note that the pH boost of adding kalk to the tank is a temporary, non-equilibrium effect that will dissipate as gas exchange from the tank water to the room air "catches up". So to make the pH effect useful, you'll want a dosing pump that is capable of relatively slow speeds and is rated for continuous operation. The absolutely ideal theoretical method would be to calculate the tank's consumption, figure out how much kalk you need to meet that consumption (which you've already done), and then set the flow rate of the dosing pump so that the speed it runs at will yield the exact amount you require over the time period that you're dosing it.

Note that I mention "the time period that you're dosing it" instead of 24 hours. Depending on your particular tank's pH cycle behavior, you could choose to only spread the kalk dose over the nighttime hours and have it off during the day, or if the indoor CO2 concentration in your home is really high (>600 ppm), over a 24 hour period.

I’m currently using a DŌS to deliver alkalinity to my system, and it’s capable of dosing in small increments and at specified times, so I’ll consider the continual usage of it.

Another tip about kalk reactors - to be really useful, they require at least weekly maintenance. Specifically, as new RODI enters the unit, the dissolved CO2 that comes along with it will react with the kalk to form calcium carbonate, which is insoluble and becomes incorporated into the undissolved slurry at the bottom of the reactor. Not only that, individual particles of calcium hydroxide (kalk) can become coated with calcium carbonate as the surface of the particle reacts with the CO2 coming in with the RODI.

The bottom line is that the reactor needs to be emptied out completely, rinsed, and re-charged with kalk powder occasionally, and more kalk powder needs to be added on at least a weekly basis even if there's visible slurry on the bottom of the reactor, since a substantial amount of that visible slurry may be calcium carbonate or calcium carbonate-coated kalk powder.

I don’t mind the maintenance that my system requires, and I think that the Avast Marine stirrer seems that it would be easy to maintain, so I’ll do some research on it. While I am at it, I will compare the cost-effectiveness of two-part and calcium hydroxide to see if it will make sense for me. I don’t want to trade the ease of tailoring calcium and alkalinity dosing for a single solution and still need to supplement with two-part; that would defeat the purpose of my consideration to switch.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t mind the maintenance that my system requires, and I think that the Avast Marine stirrer seems that it would be easy to maintain, so I’ll do some research on it. While I am at it, I will compare the cost-effectiveness of two-part and calcium hydroxide to see if it will make sense for me. I don’t want to trade the ease of tailoring calcium and alkalinity dosing for a single solution and still need to supplement with two-part; that would defeat the purpose of my consideration to switch.

Unless space is at a premium, I'm much more a fan of dosing from a settled reservoir than a stirrer. I used two 44 gallon brute cans plumbed together so I refilled it less than once a month. Stirrers are hard to control the dose, and often undersaturate the water (though not all folks want that anyway)..

 

[Waynerock]

How awesome is that calculator? Just a side note I have been using that same one for a little bit and always keep it bookmarked on my phone as use it almost daily!! Thanks to all involved

 

[blasterman]

Sorry. Let me be clearer....

Dont don't it...unless you have tracked your Alk over the course of a month or so.

Kalkwasser can jump dKH in a hurry. Problem is Kalk is calcium and carbonate in one mix.

The advantage of 2Part is you can tailor make your calcium consumption separately from your carbonate consumption.
Kalk is cheap....but wicked if you dont know your consumption rates.

Hth

This. Kalk is fine in low consumption tank or for ATO. In higher consumption tanks the amount of kalk water you need to keep calcium up is staggering and will result in a constant pH jumps that can cause localized precip of calcium. Give it a try, but once corals take off you'll probably end up reaching for the good old box of arm and hammer.

 

[Green1181]

Unless space is at a premium, I'm much more a fan of dosing from a settled reservoir than a stirrer. I used two 44 gallon brute cans plumbed together so I refilled it less than once a month. Stirrers are hard to control the dose, and often undersaturate the water (though not all folks want that anyway)..

Hey Randy, Do you use the 44 gallon cans for ATO or for dosing kalk separately? I would like to start dosing and thought a reactor would give me more control than my ato which just dumps large amounts in at a time.

 

[Randy Holmes-Farley Verified Community Expert]

Hey Randy, Do you use the 44 gallon cans for ATO or for dosing kalk separately? I would like to start dosing and thought a reactor would give me more control than my ato which just dumps large amounts in at a time.

I put limewater (kalk) in the ato. Doing it again, I might dose pump the limewater.

Not a huge fan of reactors since they can be hard to control potency, but sudden dumping of large amounts may not be desirable either.