Ion balance with calcium + sodium hydroxide dosing

[andrek787]

I currently have a 7-8 month old SPS\LPS reef tank with relatively low calcium consumption. In order to maintain high PH (8.25 - 8.45) I am dosing 1.25L of fully saturated kalkwasser and 30ml of sodium hydroxide solution @ 283g per gallon concentration. This is maintaining my KH around 9.5 and calcium around 480-500, however the magnesium is drifting down as would be expected.

I am wondering if dosing a mixture of Magnesium/Potassium Chlorides and Tropic Marin Part C would offset the ion imbalance created by the hydroxide salts.

 

[dwest]

The kalk supplies both calcium and alkalinity in roughly equal proportions.

The sodium hydroxide supplies alkalinity, but not calcium. I would expect that your calcium levels should be dropping.

You can make mixtures of mag chloride with mag sulfate and add as needed. That’s what I do.

Part C can offset imbalance of traditional 2 part, but you are not doing that.

 

[andrek787]

I have tried to meet the alkalinity demand by using just kalkwasser but my calcium kept going up over 500. Sodium Hydroxide seems to be much better at elevating PH compared to Kalkwasser.

 

[Randy Holmes-Farley Verified Community Expert]

There’s no rationale for potassium chloride dosing, unless a test suggests you need it, if you use Balling Part C, which is what I recommend in this situation.

Heres the recipe:

https://www.reef2reef.com/threads/diy-three-part-with-balling-part-c-recipe.1063575/