What you won't reef with out

[Zero Nitrates]

A good skimmer.

 

[Duffam3434]

Rev says... Clownfish!! That's Funny!! Skimmer, sterilizer and good lights!! Make the difference.

 

[FaviaFreak]

water changes with a good salt brand

 

[theguy67]

a lot of what is being posted ( skimmer, water changes,) can all be substituted.

What I will not reef without is--

1. A tank
2. Water (as mentioned)
3. Salt

You really don't even need lights for some coral.

 

[3Twinklets]

It is a toss up between skimmer and power heads in my case. I also need a chiller

 

[reid429]

Lights