RO Water in the New Fish Room or Not?

[Shenandoah Aquatics]

Calling all fish room experts! I am really going back and forth in putting an entire RO system for the new fish room or not. I am on city water, so I will have to get a carbon block at the very least to keep the chlorine out. But my water right now is super hard, liquid rock, which I absolutely love having since I enjoy a lot of livebearers. What would you advise? I have three options I believe. I should also say that I will be setting up an auto water change system as well. 

Option #1: Put in a RO system for the whole fish room and use crushed coral or other things in the aquariums that I need a higher TDS

Option #2: Use the city water, put in a carbon block and filters to remove chlorine. 

Option #3: Put in RO system but only have one rack on the system. Use the rest of the racks on the city water. 

[lefty o]

run carbon or use a dechlorinator.

[Tihshho]

It all depends on what you want to keep, how much you want to go into chasing params, and if you have the space to store RO. 

IME having RO/DI and a storage vat to hold a significant amount of water has been handy, and I'm not on city water. I'm able to replicate water for fresh wildcaught imports faster and don't have to fight my out of the tap parameters to do so. Those on city water or those who constantly test their source water and notice seasonal changes due to how water processing plants treat their local water, or how well folk (like myself) get seasonal changes due to agricultural pesticides and ferts mean that you can disregard those changes as long as your RO/DI unit is maintained. I'm not going to say it's necessary, but it is helpful.

[Tedrock]

First off I am no expert but I struggled with this same issue.  
 

I built a “fishroom” 20 tanks and my city water is not bad but breeding was my goal. I wanted to more successful with shrimp and so I took the plunge.  I bought a RO DI system during Black Friday.  It has made a difference in breeding but I would say it is not absolutely necessary.  I am a shrimp person so remineralization is a must so you need to ask what is your end goal.    It makes top off’s and water changing super easy but you have keep in mind it is an added cost.

Tedrock