ro vs ro/di


New member
i am going to buy a water filter instead of buying water from the local fish store. i am confused as to what type of filter to buy. i am planning on a FOWLR with a wet/dry sump. Do i need a RO/DI, or is that mainly for reef tanks? am i okay with just a RO filter since i am not going to have any corals?


New member
Using just RO water is better than tap water. I did the same as you are thinking as a matter of fact. I started out with just an RO filter to save a little money. When I could I added a DI unit later. If you haven't bought yet I highly recommend giving the guys at a call. They are a wealth of info and a pleasure to deal with. Ask around a little bit and you will hear the same from many loyal customers of theirs.
P.S. welcome to RC


New member
Welcome to RC!
If you're going to spend the $ on a unit, I would get RO/DI
When I check TDS on RO, I get 3ppm.
RO/DI I get 0
If this will also double as drinking water, get a DI bypass. has good units at a good price.
You may not have corals now, but if you stick w/ this hobby that may change sooner than you think, especially the more you read this site!


Team RC
Definitely add the DI stage if at all possible. Silicate is one of the first problems you might run into without it, and silicate feeds diatoms. Not good. Even with an RO you could still have a high TDS, but after the DI stage it should be 0. have great products.


In Memoriam
A lot depends on the quality of your tap water. Generally I recommend RO/DI for everyone as an RO by itself only does 90 to 98% of the treatment so there are still contaminants present that could possibly do harm. The intital cost difference between the two is minimal so I would get the RO/DI to begin with rather than having to go back and add it later. I would always get a good handheld TDS meter to go with it to test the efficiency and condition of the unit on a regular basis.


New member
thanks for the quick response. I will start my research for a RO/DI unit. looks like the filter guys and air water ice are the 2 most recomended on this board.