I have browsed old posts but not much on this topic. I am considering buying a used setup. I had a salt tank 20 years ago fish only plus one annenome (undergravel, 30L, power filter, crushed coral) ran flawless for a few years than lost everything in less than 2 days. Still have the tank but has been fresh since, still running undergravel with power filter.
So, I am considering something between 55G -75G. From previous posts I read it seems that I can reuse the sand but should rinse out first, dump the water and use new RO water with salt mix, reuse live rock as is, fish should transport fine in bags.
What should I be careful to avoid when used tank setup shopping? There seems like there have been a few ranging from $400-$600 with various equipment.