Any recommendations for an RO filter system?

I don't have a RO system, but have that purchase on my list. My impression is a 3-stage is fine for homebrewers. Make sure any system you get uses standard filters.

Here are a couple places that were recommended by a lot of people on homebrewtalk a couple years ago
https://airwaterice.com/drinking-water-system.html
http://www.bulkreefsupply.com/

 

Just remember you get what you pay for, and with the low water tables in LA you may want to opt for a better RO. The better option might be to just buy the 5gal RO water at the store if just using for brewing.

Of course I'm also a proponent of using local materials and flavors that using indigenous water brings, so you might want to try a campden tab in the kettle to zap the chlorine and leave the water as-is, and see which styles work with the water profile (cream ales/lagers/etc).

 

FWIW, I was supplying RO/DI water to my 500gal reef tank and used an airwaterice unit, (I was making about 200+ gallons per month). I have since gotten out of the saltwater hobby and now use the device to occasionally make water for my beer concoctions, bypassing the DI part of my filter unit and just getting the RO water.

There are other great companies out there as well, but airwaterice is one that the "reefers" use and trust.

 

Spectrapure is another favorite.

http://spectrapure.com/RO-RODI/RO-SYSTEMS