Who's Good at Chemistry?

[JMSKI333]

Fello Reefers!

I am currently trying to dial in my alkalinity in my 90 gallon reef. I have a mix of SPS and LPS at about half capacity.

At the Beginning of my testing (red sea) my parameters were as follows:

Calcium = 485
Alkalinity = 5.6
Mag = 1300
Salinity = 1.026

I knew I wanted to raise my Alk and lower my calcium a bit, so I started dosing baking soda in my top off. After a series of mixes, I slowly dialed in my current Sodium Bicarbonate consumption at 1 1/4 tsp per gallon and I top off a gallon of this solution a day. So my consumption is 1 1/4 tsp of baking soda per day.

My current Parameters are as below:

Calcium = 430
Alkalinity = 8.5
Mag = 1280
Salinity = 1.026

Now that I have everything where I need it to be, how do I convert to Kalkwasser? Is there any way to convert 1 1/4tsp of baking soda a day to an equal dosing of kalkwasser? I don't want to have to go through all the trial and error with the kalkwasser if possible. Ideally, I'd like to just switch out the baking soda for kalkwasser to my gallon per day top off.

Any input is appreciated!
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[Russellaqua]

The difficulty you will have here is that kalkwasser contains calcium hydroxide (Ca(OH)2.) When the powder is added to water it breaks into Ca and 2 OH ions, and the 2 OH ions can further react with CO2 in the water and form HCO3 (bicarbonate), the main contributor to alkalinity in marine systems. In this situation using an equal amount of kalkwasser will add an equal amount of bicarbonate when compared to the sodium bicarbonate, but it will also add calcium. If the tank inhabitants can consume this much calcium daily, you're all set using the same amount of kalkwasser as you were of sodium bicarbonate. You really won't know without trying and testing. It could be calculated out if we knew the mass of the amount of 1 1/4 tsp kalkwasser (but I don't know it), and the rate at which your tank consumes calcium. Kalk is mainly a calcium supplement in my opinion, and you may need to use other methods to keep your alkalinity stable between kalk dosings.

 

[JMSKI333]

Mark,

Great info! Thanks for your input! According to "When Do Calcium and Alkalinity Demand Not Exactly Balance?" by Randy Holmes Farley, our tanks consume exactly 20ppm a calcium for every 1 ml/l of Alkalinity during the coral calcification process. We just don't notice the drop or rise of Calcium nearly as much as Alkalinity due their 10:1 relationship.

With that being said, if what you are saying is correct, then I should try switching out the 1 1/4 tsp of Sodium Bicarbonate with the Kalkwasser. It would probably be a good starting point anyways. I am assuming (hoping) my Calcium intake coincides with my Alkalinity.