if u do it this way, then its not worth the effort...might as well get salt??
seawater that LFSes are selling are usually prefiltered...i prefer them to saltmix..but i know a lot of reefers will prefer otherwise...
as most mentioned, seawater around singapore is not very clean..look at the no. of ships running in singapore water..most importantly, sinagpore has the BUSIEST port so the water around us is not really clean...