dolomite in the calcium reactor
- Thread starter rhoptowit
- Start date
Be sure to start with normal magnesium levels. This method cannot be used to boost magnesium as the alkalinity will get too high. I discuss it here:
Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm
from it:
t has been suggested that adding dolomite to CaCO3/CO2 reactors can help with magnesium problems. Dolomite is a material that contains both magnesium and calcium carbonate. If dolomite is being added to the reactor to maintain existing appropriate magnesium levels against the continual depletion via calcification (for example, if the calcium carbonate being used is too low in magnesium to maintain adequate magnesium) then this is a fine approach.
However, this method is unsuitable if the goal is to raise magnesium levels. The problem is that for every magnesium ion released from the dolomite, 2 units of alkalinity are also released:
MgCO3 ---> Mg++ + CO3--
Consequently, if one wants to raise magnesium by 100 ppm, the alkalinity will necessarily rise by 8.2 meq/L (23 dKH). The only way around this problem is to add a mineral acid (not vinegar) to the aquarium to reduce the alkalinity, and that may be more problematic than just adding magnesium in the first place.
Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm
from it:
t has been suggested that adding dolomite to CaCO3/CO2 reactors can help with magnesium problems. Dolomite is a material that contains both magnesium and calcium carbonate. If dolomite is being added to the reactor to maintain existing appropriate magnesium levels against the continual depletion via calcification (for example, if the calcium carbonate being used is too low in magnesium to maintain adequate magnesium) then this is a fine approach.
However, this method is unsuitable if the goal is to raise magnesium levels. The problem is that for every magnesium ion released from the dolomite, 2 units of alkalinity are also released:
MgCO3 ---> Mg++ + CO3--
Consequently, if one wants to raise magnesium by 100 ppm, the alkalinity will necessarily rise by 8.2 meq/L (23 dKH). The only way around this problem is to add a mineral acid (not vinegar) to the aquarium to reduce the alkalinity, and that may be more problematic than just adding magnesium in the first place.
You're welcome.
Happy reefing.
Happy reefing.
rhoptowit
New member
actually randy i have one more question.
a friend of mine brought up that since the chemical formula for dolomite is MnCa(CO3)2 wont its dissociation go like this...
MgCO3 + Ca2+ + HCO3-
then too
Mg2+ + HCO3-
by looking at that dolomite then also releases a calcium ion for every magnesium ion right?
a friend of mine brought up that since the chemical formula for dolomite is MnCa(CO3)2 wont its dissociation go like this...
MgCO3 + Ca2+ + HCO3-
then too
Mg2+ + HCO3-
by looking at that dolomite then also releases a calcium ion for every magnesium ion right?
Yes, dolomite will release equal numbers of calcium and magnesium ions, along with the carbonate (CO<sub>3</sub><sup>--</sup>) ions. Some of the carbonate likely will be converted to bicarbonate (HCO<sub>3</sub><sup>-</sup>), but most likely not all. This article discusses alkalinity:
http://www.advancedaquarist.com/2002/2/chemistry
http://www.advancedaquarist.com/2002/2/chemistry
I agree. However much calcium is in the dolomite will act just like the rest of the calcium carbonate media, releasing calcium and carbonate. The first thing released is carbonate, but that can rapidly be protonated to form bicarbonate.
That's probably your secret to success.
by looking at that dolomite then also releases a calcium ion for every magnesium ion right?
No really Dolomite is made of alternating mono-layers of Magnesite, MgCO3 and Calcite, CaCO3. Magnesite is less soluble than Calcite by a long shot. So, more Calcite will dissolve in x time than Magnesite. This is the reason why some industries that use Dolomite use Activated Dolomite, which increases the rate of dissolution of the Magnesite, MgCO3.
No really
Dolomite is made of alternating mono-layers of Magnesite, MgCO3 and Calcite, CaCO3. Magnesite is less soluble than Calcite by a long shot. So, more Calcite will dissolve in x time than Magnesite. This is the reason why some industries that use Dolomite use Activated Dolomite, which increases the rate of dissolution of the Magnesite, MgCO3.
