Randy Holmes-Farley
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Reef Chemistry Question of the Day #114
Many aquarists using GFO (granular ferric oxide) as a phosphate binder have reported significant precipitation of carbonates on the solid GFO and elsewhere in the system. Such precipitation can, for example, be a contributing factor in the caking of such materials and can coat other surfaces in the aquarium. This precipitation can also contribute to a detectable drop in alkalinity, and possibly pH, as it removes carbonate from the water column.
Dissolution of these precipitates with acid, accompanied by bubbling, indicates that these deposits are carbonates and are most likely calcium carbonate because it is supersaturated in most reef aquaria (and in the ocean).
Which of the following is the least likely explanation for the precipitation of calcium carbonate when using GFO?
A. Removal of nearly all of the phosphate from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
B. Addition of soluble iron to the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
C. Removal of nearly all of the strontium from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
D. Removal of many organics from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
Good luck!
.
Many aquarists using GFO (granular ferric oxide) as a phosphate binder have reported significant precipitation of carbonates on the solid GFO and elsewhere in the system. Such precipitation can, for example, be a contributing factor in the caking of such materials and can coat other surfaces in the aquarium. This precipitation can also contribute to a detectable drop in alkalinity, and possibly pH, as it removes carbonate from the water column.
Dissolution of these precipitates with acid, accompanied by bubbling, indicates that these deposits are carbonates and are most likely calcium carbonate because it is supersaturated in most reef aquaria (and in the ocean).
Which of the following is the least likely explanation for the precipitation of calcium carbonate when using GFO?
A. Removal of nearly all of the phosphate from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
B. Addition of soluble iron to the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
C. Removal of nearly all of the strontium from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
D. Removal of many organics from the water in the vicinity of the GFO may accelerate the precipitation of calcium carbonate.
Good luck!
.