"Furthermore, the amount of aluminum that is released is in the microgram range. In other words, an extremely low level that from a chemical standpoint would be characterized as "non-soluble" i.e. non-soluble material is not released into the solvent (i.e. water). Any search on the solubility characteristics of aluminum oxide would show it to be considered completely insoluble in water.
The bottom line is that if the directions are followed and the product is well rinsed in freshwater, any deleterious effects should be minimal to non-existant and temporary."</em>
This material is a form of 'activated' ceramic (microporous), also called alumina (Al2O3). Alumina is considered to be inert (non-reactive). There will be some free aluminum present left over from the manufacturing process.
Just because we can detect it, does not necessarily mean it causes a problem.
As stated by the manufacturer...'use as directed, and RINSE WELL'.
I have used it, with soft corals, without incident. I do not currently use it, but as stated, there are many others that do.
MY bottom line: please be very careful of 'witch hunts'. Most of what goes wrong in an aquarium can be traced back to basic maintenance, -jmho.