RO units?

[nutrak]

I dont have a lot of algae in my 150 reef. it grows on the rocks some, but its more just discoloring them to a dull brown over a period of months. i dont have hair algae, and its all brown.
do i need a reverse osmosis unit? i live in boston MA if that helps.
is a 3 stage significantly better than 2 stage?
is 4 stage necessary?

please advise before i do something to feel trendy.
joe

 

[loganj]

Sounds like diatoms to me. These are probably due to silicates in the tap water. An RO unit is a good thing to have...it insures that you get only pure water with no contaminants. A 2 stage usually has a sediment/carbon combo and the RO membrane. A 3 stage will have separate sediment and carbon filters. It will require less frequent filter changes. The 4 stage incorporates a DI cartridge. The DI removes what the RO membrane misses. It is generally recommended to buy a unit with DI because it will give you water that is very pure.