quarantine tank/tanks

Hey all need some advice on quarantine fish and coral.

I'm currently looking at purchasing 3x 8 litre tanks along with a 20l tank to quarantine fish and corals. Looking at ways to " Jerry rig" them together.

also looking at using old ro/Id from water changes to use as water instead of cycling the tanks ( as no live rock or live sand will be introduced) sorry I'm Penny pinching.

Just started the hobby