You wont believe

[200 gallon reef]

So listen to this story . . . . . I bought an rodi system over a year ago. I put all new filters in it when I bought it. Approx 2 months later my di is shot and I am reading 10 ppm out of the system. I know I make about 50 gallons a week so maybe it was just time. So I bought another round of filters. Same as last time about 2 months and it is shot. I talked to my lfs and said how long are these membranes and filters supposed to last? When I heard a year I said to myself something must be wrong. So I thought about it and it occured to me, I have a lot of water pressure in my house. I did some research and found that these systems are supposed to operate at about 45 psi. I bought an inline water gauge and hooked it up. . . . . . . . .
U won't believe 75 psi ! That explains it

 

[Phranque]

More sage advice from another lfs.... 75psi is perfectly fine for RODI systems. Many systems even recommend a booster pump at 45-50psi or lower.
At 50 gallons a week, you're very lucky to get two months out of a DI canister. My water pressure is 80psi. My tap water is about 450TDS, my RO water is 8TDS, which is better than 98% rejection, and a standard 10" DI canister lasts me about 150-200 gallons before needing refilled.

 

[AquaRick]

The higher pressure actually helps your rodi system, not the other way around. I'm thinking the quality of your water is pretty bad to begin with.

I make about 60g a week and I haven't had to replace any filters yet since I bought the system a year ago. Water is testing at 5 tds out of the tap with 45 psi.

 

[200 gallon reef]

Im going to dig a lil deeper

 

[Bige]

75 psi or 5.5 bar is recommended pressure. My tap is at 120 psi so I have to turn mine down. If your changing 400 gallons in two months with 450 Tds, I think that's what your going to get.