Freshwater to Marine Aquarium conversion...?

Hi Guys
Im a noob here, but been a fish keeper for over 30 years .

Currently been keeping Malawis for the last 5 years and have a salty itch to scratch....

Current set up is 5'6x2'x2' using three external Eheims and cheap Led array.

What would I need to convert this into a nice Reef tank ?

Im thinking:

Sump it for starters - not sure how hard this is to do on a standard tank RE the weir ?

Return pump

Skimmer

Lighting - would like a dimming LED setup and no Halides if poss.

Wavemakers

Live Rock

Not looking to keep hard to keep species as never kept Salties before, but love the look of a good Reef setup.

Also, what do I need for water changes ?

Currently fill a 220 ltr butt via 10 litre Purolite filter and 2 stage HMA, and Im pretty sure Id have to get an RO set up.

Been a fishkeeper for more years than I can think, and just fancy trying the Salty side.

Is it worth trying to convert or should I just sell up and buy again ?

Any help and advice welcome please guys.
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