To advocate and endorse using tap water in salt water mixed for reef tank is definitely the wrong direction and ill advice for new reefers.
Tap water condition differs in different location in Singapore.
Advanced and seniors reefers have the experience and the ability to rectify the situation if something goes wrong in the tank.
Reefers have different reef tanks that require different water quality.
To have countless problems related to water condition and fail when starting a reefing hobby can be very demoralising and unnecessary.
So do it right the first time.
Rgds,
mike