Starting kalk dose?

[CloudReefer]

I have 66g of water volume, and my tank consumes about 0.3dkh of alk per day. I used Randy's calculator and it says to add 650mL of saturated kalk for a 0.3dkh increase in alk. I would start at half that and measure to see the results (dosing overnight for 12 hours), but even 325mL seems like a lot of kalk. Can anyone confirm this dosage? I want to avoid pH or alk spikes.

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

I have 66g of water volume, and my tank consumes about 0.3dkh of alk per day. I used Randy's calculator and it says to add 650mL of saturated kalk for a 0.3dkh increase in alk. I would start at half that and measure to see the results (dosing overnight for 12 hours), but even 325mL seems like a lot of kalk. Can anyone confirm this dosage? I want to avoid pH or alk spikes.

Thanks!

It's correct. Kalkwasser is necessarily quite dilute.

 

[piranhaman00]

Yes it’s shocking to add gallons of the stuff per day but that’s how it goes

 

[CloudReefer]

Thanks for confirming! Would you please share how to math out the pH increase one should expect from a given amount of saturated kalk?

It's correct. Kalkwasser is necessarily quite dilute.

 

[bradreef]

On 66 gallons you could eventually end up 2000-3000 ml per day. I would guess that is close you your evap? 1/2 gallon or so per day?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for confirming! Would you please share how to math out the pH increase one should expect from a given amount of saturated kalk?

No, one cannot do such a calculation because it depends on a variety of factors, the big one of which is unknowable (that is, how fast your tank aeration pulls in CO2 from the air to offset the pH rise).

Almost no one gets pH too high from replacing all evaporated water with kalkwasser. I would not worry about that.

IF one were to add it all at once (which you should not do), adding 1.25% of the tank water volume in saturated kalkwasser (boosting alk by 1.4 dKH) the pH will rise by about 0.65 pH units instantly (lower at higher alkalinity). That applies to any hydroxide adding method, and is about twice the pH boost when using carbonate to add alk.

If that is spread out over many hours, the pH effect is far lower as the tank begins pulling in CO2 from the air.

 

[CloudReefer]

No, one cannot do such a calculation because it depends on a variety of factors, the big one of which is unknowable (that is, how fast your tank aeration pulls in CO2 from the air to offset the pH rise).

Almost no one gets pH too high from replacing all evaporated water with kalkwasser. I would not worry about that.

IF one were to add it all at once (which you should not do), adding 1.25% of the tank water volume in saturated kalkwasser (boosting alk by 1.4 dKH) the pH will rise by about 0.65 pH units instantly (lower at higher alkalinity). That applies to any hydroxide adding method, and is about twice the pH boost when using carbonate to add alk.

If that is spread out over many hours, the pH effect is far lower as the tank begins pulling in CO2 from the air.

Perfect! Thank you for the thorough explanation!

 

[CloudReefer]

On 66 gallons you could eventually end up 2000-3000 ml per day. I would guess that is close you your evap? 1/2 gallon or so per day?

Correct! Right now it's closer to 1g per day but come summer when the heat isn't running it goes down to a little over 1/2 gallon per day.

I figure once I need more than 2L per day of kalk I'll start increasing the amount of All for Reef I'm using to keep up with demand.

I only have a few corals in the tank. Most of the demand is coming from my bivalves (got lots of em as hitchhikers on FL live rock and they are spreading to the "dead" rock) and snails. I'm guessing corraline accounts for the rest. I suspect once I start adding tridacnids and more corals the kalk alone will not be nearly enough. I remember adding a single small squamosa to a previous tank and being amazed by how much alk and Ca it used.

 

[Randy Holmes-Farley Verified Community Expert]

Perfect! Thank you for the thorough explanation!

You're welcome.

Happy reefing.

 

[CloudReefer]

You're welcome.

Happy reefing.

@Randy Holmes-Farley
Is cloudy kalk mix safe to use?

I mixed 24g of kalk (seachem) into 4 gallons of water and let it sit overnight. Still very cloudy.

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley
Is cloudy kalk mix safe to use?

I mixed 24g of kalk (seachem) into 4 gallons of water and let it sit overnight. Still very cloudy.

It may be a little more potent than saturation (if the cloudiness is undissolved calcium hydroxide, not if it is calcium carbonate), but I'd use it if it has sat overnight without any stirring.

 

[CloudReefer]

It may be a little more potent than saturation (if the cloudiness is undissolved calcium hydroxide, not if it is calcium carbonate), but I'd use it if it has sat overnight without any stirring.

Thank you as always for sharing your knowledge and experience!

 

[MIke Wood]

@Randy Holmes-Farley
Is cloudy kalk mix safe to use?

I mixed 24g of kalk (seachem) into 4 gallons of water and let it sit overnight. Still very cloudy.

i just started dosing kalk as well and was actually surprised how cloudy is was in a 5 gallon bucket. cant really see the bottom but my ph probe says its ph is 12.3 so a little under fully saturated. my tank takes .4dkh per day and i did not notice any ph increase. tank volume is 64 total gallons.

 

[Randy Holmes-Farley Verified Community Expert]

i just started dosing kalk as well and was actually surprised how cloudy is was in a 5 gallon bucket. cant really see the bottom but my ph probe says its ph is 12.3 so a little under fully saturated. my tank takes .4dkh per day and i did not notice any ph increase. tank volume is 64 total gallons.

0.4 dKh per day is a low dose so will have a low ph effect. Even added all at once, the ph boost will only be about 0.2 ph units, and spread out the apparent rise will be much smaller.

 

[ESABOE]

Sliding into this thread. @Randy Holmes-Farley I have read a lot about the benefits of Kalk dosing, but not positive on equipment required to use it effectively; specifically a Skimmer.

My tank is new, 5 months old, and is fairly low-tech. I have the Red Sea ReefMat; a UV Sterilizer on a dedicated pump. No skimmer, no reactors, no fuge. I do have TBS rubble and also a Chemi-Pure Blue bag in sump.

The only “dosing” I am doing at the moment is ARF and Brightwell’s Coral Amino.

Can I still dose Kalk without a skimmer?

 

[MIke Wood]

0.4 dKh per day is a low dose so will have a low ph effect. Even added all at once, the ph boost will only be about 0.2 ph units, and spread out the apparent rise will be much smaller.

My PH at night is 7.8. tops at 8.01-8.03 during the lighted hours. dont have much room to add a refugium. skimmer line is plumbed to outside air. Would you recommend running the kalk strictly at night and just deal with the fluctuation of alk from day to night? or will that not even cause a huge bump in ph anyway at night?

 

[CloudReefer]

Sliding into this thread. @Randy Holmes-Farley I have read a lot about the benefits of Kalk dosing, but not positive on equipment required to use it effectively; specifically a Skimmer.

My tank is new, 5 months old, and is fairly low-tech. I have the Red Sea ReefMat; a UV Sterilizer on a dedicated pump. No skimmer, no reactors, no fuge. I do have TBS rubble and also a Chemi-Pure Blue bag in sump.

The only “dosing” I am doing at the moment is ARF and Brightwell’s Coral Amino.

Can I still dose Kalk without a skimmer?

I think I can answer this one! lol

Yes you can dose kalk without a skimmer.

 

[Randy Holmes-Farley Verified Community Expert]

The only issue is that the pH may possibly rise substantially.

When I took my skimmer offline for a few weeks, the pH rise was the main thing I noted. I dosed limewater (kalkwasser) for all calcium and alk.

 

[CloudReefer]

The only issue is that the pH may possibly rise substantially.

When I took my skimmer offline for a few weeks, the pH rise was the main thing I noted. I dosed limewater (kalkwasser) for all calcium and alk.

Why would not having a skimmer increase the pH? Does it have something to do with the oxygen and carbon levels in the water? Or less gas exchange generally?

 

[Randy Holmes-Farley Verified Community Expert]

Why would not having a skimmer increase the pH? Does it have something to do with the oxygen and carbon levels in the water? Or less gas exchange generally?

Adding kalkwasser creates a CO2 level in the water that is lower than was there before you added it, which raises pH. A skimmer allows the tank to pull in CO2 from the air faster:

Ca(OH)2 --> Ca+ + 2OH-

OH- + CO2 --> HCO3-