Reef Chemistry Question of the Day #210 Limewater/Kalkwasser Long Term Use

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #210

Suppose that you have a coral reef aquarium where you dose limewater (kalkwasser) daily to replace most of the evaporated water. You have adjusted the concentration of dry solid calcium hydroxide added to the freshwater so that the aquarium maintains an alkalinity of 8 dKH as measured with a Salifert test kit.

You experience a daily pH range from 8.0 to 8.2, and you perform no water changes and use no other additives.

Which of the following will likely happen long term (weeks to months)? List all that apply.

A. Calcium will slowly rise
B. Calcium will slowly fall
C. Magnesium will slowly rise
D. Magnesium will slowly fall
E. The true carbonate alkalinity will slowly decline as it is replaced by hydroxide alkalinity
F. The true carbonate alkalinity remains unchanged but the total alkalinity increases due to accumulation of hydroxide


Good luck!













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[LobsterOfJustice]

Definitely D, probably A, and I don't know about E/F but F sounds plausible.

 

[CNDReef]

B
D

 

[acer]

OHHH- cant wait to see what the correct answers are. IMO - likely B, D and don't know about E,F. Since I run my system close to this scenario - (just add mag per testing results ever few weeks) - I will follow along.

 

[jeffp1]

A
D

 

[drawman]

A, D, and probably F

 

[Scarybo]

D based on the magnesium usage by the tank inhabitants. This in my understanding is because magnesium is only slightly affected by Kalk, but the true decline is caused by usage not a chemical reaction. But I could be completely wrong.

 

[siggy]

when you absolutely don't know go with D

 

[sghera64]

D based on the magnesium usage by the tank inhabitants. This in my understanding is because magnesium is only slightly affected by Kalk, but the true decline is caused by usage not a chemical reaction. But I could be completely wrong.

I see your 'D' and raise you an 'A'. Because: if Mg++ is taken up by the coral in place of the Ca++, then as Mg++ is slowly depleted, Ca++ will slowly accumulate.

Therefore: A and D.

 

[bif24701]

D?

 

[jason2459]

I say A and B and C and D as my reagents go bad and I buy new kits.

 

[rushbattle]

A and D only.

 

[rock_lobster]

ADF

 

[cracker]

I say D is the answer. I don't know if my "Red Sea test kit " responds to hydroxide and or true carbonate . I do know The Mg drops over time . However our Master Chemist mentions a selifert kit, which I suspect is significant. The plot thickens !

 

[rstrann]

B and D only. E tempted me, but I think it's a red herring lol

 

[Alfrareef]

Don't have a clue but would like to know...

 

[Ty Hamatake]

I'm definitely gonna have to go with D.

 

[Hreef]

F

 

[CindyKz]

D and E. A might happen depending on calcium consumption by the tank inhabitants.

 

[BigJohnny]

What's the answer @Randy Holmes-Farley