Two part, precipitation in calcium solution

[Carla2]

Hi Reef2Reef, I've been dosing my tank according to Randy's two part recipe for a few months. The first time I made the calcium solution, after a few hours a little white powder had precipitated on the bottom. Yesterday I made a new batch and made sure in the bucket that all the calcium chloride had dissolved but the same thing happened again and now I see a little white powder on the bottom. Is this normal?

(long story)

I'm wondering if I did something wrong. I use Kent TurboCalcium (anhydrous calcium chloride). The recipe says, dissolve 500 grams of calcium chloride dihydrate to make 1 gallon total volume. If you use anhydrous calcium chloride you should use about 20% less solid calcium chloride by volume. The problem was that I didn't know the precise volume of calcium chloride dihydrate (Dowflake) necessary, so I wasn't sure what volume of Kent TurboCalcium I should use. So I tried calculating the necessary weight. Time to go back to high school ...

The Alkalinity part uses 594 grams (7.07mol) sodium bicarbonate. When it is baked in Recipe #1, the chemical reaction
2NaHCO3 → Na2CO3 + H2O + CO2
should take place, so this yields 7.07/2 = 3.535 mol sodium carbonate.

As I should use 3.535 mol anhydrous calcium chloride (111g/mol), I need 111*3.535 = 392 grams per gallon solution.

I actually use 2L (0.528 gal) containers, so I instead used 392*0.528 = 207 grams of Kent TurboCalcium. The calcium chloride seems to dissolve while being stirred, getting hot even though I do it little by little, and after a few hours a little white powder precipitates on the bottom of the container.

Is this fine to use, or should I try adding less Kent TurboCalcium next time? Thanks!

 

[Randy Holmes-Farley]

500 grams of calcium chloride dihydrate = ~377 grams of anhydrous calcium chloride.

For purposes of this two part, it's just an estimate since the Kent product is unlikely exactly zero moisture and the Dowflake I used in the initial recipe was not exactly the dihydrate.

The precipitate is not likely anything to worry about. Many of the anhydrous calcium chloride products have it. It might just be calcium carbonate.

 

[Carla2]

So I used a little more Kent TurboCalcium than necessary (392 grams instead of 377 grams). I also disregarded the presence of water in the product completely ...

If it's nothing to worry about, I will just add the precipitation with the solution and keep testing. Thanks Randy!

 

[Randy Holmes-Farley]

So I used a little more Kent TurboCalcium than necessary (392 grams instead of 377 grams). I also disregarded the presence of water in the product completely ...

If it's nothing to worry about, I will just add the precipitation with the solution and keep testing. Thanks Randy!

That's fine.

The solid precipitate can be added or not and likely makes no difference.