Alk & Ca Out of Balance

[Harrison2210]

Hi Randy

I run a 125 UK gallon sps dominated reef and am currently having difficulties with the alkalinity and calcium balance and hoped you could help as your articles have taught me everything I know (I slept through most of chemistry at school!).

Current Readings

Calcium ââ"šÂ¬Ã¢â‚¬Å“ 480ppm
Alkalinity ââ"šÂ¬Ã¢â‚¬Å“ 8.4 dkh
Magnesium ââ"šÂ¬Ã¢â‚¬Å“ 1350ppm
Ph ââ"šÂ¬Ã¢â‚¬Å“ 8.2 ââ"šÂ¬Ã¢â‚¬Å“ 8.4 (daily swing)
Salinity ââ"šÂ¬Ã¢â‚¬Å“ 1.026
Temp ââ"šÂ¬Ã¢â‚¬Å“ 25.5 c

I have been running both a Calcium Reactor & a Kalk Stirrer to keep up with demand but have been guilty of only testing alkalinity, assuming calcium would be in balance, as Iââ"šÂ¬Ã¢"žÂ¢m only adding balanced additives. I have taken the Reactor offline for the time being and am just using the stirrer to maintain ph while the calcium drops plus a little Baking Soda to keep alkalinity stable.

Could you explain what may cause this, could there be something else consuming/driving alk down causing me to add too much balanced additive.


Many Thanks

Matthew

 

[Randy Holmes-Farley]

What salt mix are you using? Some, like Oceanic, have excessive calcium in them.

This article may help:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[Harrison2210]

Thanks for the fast response I use Kent, thought it was a good salt and have not tested it since I changed over a couple months back.

Fresh batch (15 uk gallons) mixed for 48 hrs just heated up :

Calcium - 500+
Alkalinity ââ"šÂ¬Ã¢â‚¬Å“ 1.5 dkh (tested twice)

How would you recommend I proceed from here?

Cheers Again

 

[Randy Holmes-Farley]

Yes, there have been bad batches of Kent salt lately that have almost no alkalinity.

I'd probably get a different brand of salt mix (like IO) and continue normal water changes with it. Supplement some baking soda each day to help drive up alkalinity in the tank, and slowly bring down calcium.

Get an actual value for the calcium to track it by using a second syringe of titrant if necessary and add the values together.

This article and calculator will help:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

Reef Chemicals Calculator
http://home.comcast.net/~jdieck1/chem_calc3.html