sea water has certain trace elements that salt mixes dunt have. yes, its higher in nutrient but the decison is up to oneself
let me give u an example.... my gonipora did nt even open when i used synthetic salt. but when i changed to natural seawater, it bloomed and thrived. it survived for 4mnths on saltmixes then it closed up.nt opening for 1mnth. but after i change to NSW, it recovered
however be warned that water from the sea may contain parasites that can cause dieseases such as whitespot. its at your own risk. but IMHO i believe in gg natural. further more, the salt mixex try as much as possible to produce the saltwater closes to that of NSW... y nt just use the real thing.
NSW has some amt of plankton but synthetic saltmixes does nt. nt to mention the certain trace elements that cant be extracted from the sea.