RO/DI? Need help deciding

[kaytren101]

I am new to RO/DI systems. Can anyone easily explain how I'd use one for water changes? mainly for my 90g reef tank. Its completely empty as I'm doing research first. I need to know which is better a 4 stage or 6 stage. I'm watching BRS 52 Weeks of reefing and he mentioned reading a water report from the department. I see that they don't use chloramine, so that's good. But will a basic 4-stage get all this copper and lead out? or are the levels too high and i should get a 6 stage. Im TRYING to keep a low budget (I know, I know. This is NOT a cheap hobby lol)

I've also attached the pic of the report. Let me know if you can't see it.

 

[lapin]

You can use a 4 stage. Should work, however at any time your water co can change its methods. Stages can always be added if you feel they are needed later. I dont know if there is any cost saving getting it all at once (6 stage) or a 4 stage, then adding stages later. A water test (like ICP) is the only way to know if the unit is meeting your demands.