My first nano setup 14 cube or 20 long

[Aquachris]

Little background on why I'm doing what I'm doing and what I have. 

 

Currently have a 75 gallon fowlr with a green spotted puffer, 2 black mollies and 2 ocellaris clownfish. The clownfish were the recent addition and since my puffer didn't care about the mollies I was hoping it would work out.  Turns out my puffer is terrified of the clowns. He is not eating well and hides when they come around. He is bigger than them, and when food time comes he doesn't care if the mollies eat with him but as soon as those clowns get near he's gone. We are at 1.022 to 1.023 salinity in case anyone is wondering with my puffer. 

 

Decided to use this as an opportunity and do another tank and go reef this time. I don't want to do too big as I already have this 75 lol. 

 

Here's what I have that are options. 

A 14 gallon cube in my desk (aqueon 14 gallon frameless cube) or a 20 gallon long I have in my freshwater rack. 

If I do 20 long I have a decent light I could use that I could mount above the tank in the rack. If I do 14 I need a light because of where it said I don't have an option. 

I have aquaclear 30, 50 or 70 (70 is missing it's top so I'd have to find one or make my own) available. 

I want to do a skimmer if I can find a decent one as I know keeping water pristine is important since I'm thinking corals. 

I have access to plenty of live rock and sand from my 75 and I can replace that as needed with stock dry rock and sand I have. 

I figure I'd do the eheim heater just need to order one. 

Don't plan on ato away but I will probably add one in the future. 

I can raise the salinity to 1.024 to 1.025. 

 

Looking for suggestions on what others would do and recommend. I like the idea of the 14 as its on my desk but a 20 has the bigger footprint for more options. 

 

Corals I want is to be determined, right now my eye is on bta maybe gsp?  I like the kenya trees but not sold on them. I'd like to keep light reasonable cost so I know that dictates my options as well. 

Stocking will be the clowns at first not sure what I will add in the future. I do plan on adding cuc and maybe a shrimp of some kind but want to stay low on fish stock due to size.