I'm a freshwater guy who's always had an interest in marine and I'm doing my homework leading up to starting a salty tank in about 6-12 months. My question is, I'm learning about using RO/DI filters for marine water rather than tap. Is a Zero Water filter similar? If not, is there a cheaper alternative than a $150+ setup that I may not even be able to use (live in an apartment)? All advice welcome, Thanks!