View Full Version : is my alk precipitating?

jeremy K
08/19/2010, 07:53 AM
I currently dose 2 part (as per BRS, recipe 1). I notice that when I add the alkalinity, tiny flakes appear in the water. I worry that these might be precipitated calcium carbonate, which would render my alkalinity useless. Is my fear justified, or are these flakes normal?

Tank info- Calcium 500 (trying to lower to 450)
- Alkalinity ranges 7-9
- Magnesium - 1400
- Temp 78-79 degrees
- Salinity 1.026

08/19/2010, 11:46 AM
I notice if my ph is high that is what happens if the white water doesnt mix quickly its a sure sign your close to a percipitation event.

if ph is on the high side use ub baked baking soda instead of what your using now and youll be fine

watch PH is teh key here

jeremy K
08/19/2010, 12:00 PM
Interesting, because my pH is never very high. Ranges from 7.8-8.1.

08/19/2010, 12:16 PM
Mine does the same thing, PH is in the same range. BRS recipe 1.

dKH 9
Ca 420-440
SG 1.026
No Mg Test kit, but I dosed 125ml halfway through my 2-part bottles. (cyano disappeared so my Mg must have been low)

Is this normal?

08/19/2010, 01:56 PM
If you use recipe #1, this means you are using sodium carbonate, which is a high pH addtive. If too much sodium carbonate is added at one time in poor flow areas, then calcim carbonate can be precipitated due to a high local pH created where added.

IF you use recepe #2, which is sodium bicarbonate (baking soda) you do not have this concern since it will not raise your local pH. But, recipe #2 does not help increase your pH some if it is low.

The solution is to drip the sodium carbonate (recipe #1) into a high flow area & spread out the dripping over the course of day. Drip for a while, stop, then drip for a short period of time............

Randy provides more details in this article:

"What is that Precipitate in My Reef Aquarium?"

08/19/2010, 03:00 PM
The flakes might be precipitated calcium carbonate, or just magnesium hydroxide. If they seem to dissolve with some circulation, they're likely magnesium hydroxide, and that's not a problem. The article in Cliff's post describes the effect and has a picture.

jeremy K
08/19/2010, 04:06 PM
Interesting article - thanks for posting. I'll just have to drip it in slower, that's all.